# 400AH lithium cells? Best price per AH? $0.85/ AH?



## brian_ (Feb 7, 2017)

Fewer cells sounds better, but in practice I don't think that you will be able to get cells that large, at least at a reasonable price. I suggest just parallelling enough cells at the lowest level to reach your desired 400 Ah capacity, then stacking four of those sets in series to get a suitable voltage.

The cheapest source of lithium cells is probably salvaged EV battery packs; however, they may not be the desired chemistry. For RV applications LiFePO4 is often preferred, but it is not commonly used in EVs.

I have considered using Nissan Leaf modules for an RV or travel trailer. A challenge is that they are 2s2p in configuration (33 Ah per cell in the first generation, so 66 Ah and 7.5 volts per module), so they can't be combined in parallel at the cell level unless you also parallel the BMS terminals, and ensure the any current imbalance is not excessive for those smaller terminals. Only two modules would be needed for "12 volts", but a dozen modules would be needed for about the desired capacity - if they were all stacked together that would be a stack sized
11.9" (303 mm) x 8.8" (223 mm) x 16.5" (420 mm)
and 101 lbs (45.6 kgs)

Any of the pouch cell EV batteries using larger modules will be difficult to reconfigure for the desired voltage. The prismatic cells of the German brands should be easier to work with, especially the Sanyo 25 Ah cells originally used in the VW e-Golf (which has since changed to Samsung SDI) because those Samsung cells have threaded terminals (easy to build jumpers and cables). Of course with 25 Ah cells you would need (400/25)x4=64 of them.

Keep in mind that the normal operating voltage of a series set of four lithium cells - even LiFePO4 but especially automotive chemistries - is very high for the nominally 12 volt systems of an RV, and the charging voltage is even higher. You might consider a DC-to-DC regulated power supply (set for no more than 13.2 volts) for at least the more sensitive equipment. I find that furnaces make a lot of noise and may have problems even at common lead-acid charging voltage.


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## john61ct (Feb 25, 2017)

I would not recommend EV packs or second-hand cylindricals etc, in fact any chemistry but LFP for House bank usage in a mobile living space.

New quality large LFP prismatics go for $7-9 /AH before shipping, in the US market.

Do not go Alibaba direct from China, if NG you gonna pay to ship them back? Lotsa scammers out there.

Cheapest quality deep cycle **FLA** is $1 / AH.


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## brian_ (Feb 7, 2017)

john61ct said:


> I would not recommend EV packs or second-hand cylindricals etc, in fact any chemistry but LFP for House bank usage in a mobile living space.


Few RVs put the battery in the living space. they're usually on the tongue of a travel trailer, or under the floor of a motorhome. "Camper" could mean just about anything; if it means a slide-in unit carried by a pickup truck... then those have the battery within the coach body, but they should still be externally vented and sealed from the living space.

As I said, LiFePO4 (a.k.a. LFP) are commonly preferred for RVs. I think there are multiple reasons for this, including:

lack of any thermal management
low importance of power density
better voltage match to 6-cell lead-acid


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## brian_ (Feb 7, 2017)

john61ct said:


> New quality large LFP prismatics go for $7-9 /AH before shipping, in the US market.


Are CALB cells of the quality that you're describing? They're well under $2/AH per cell, which would be less than $7-9 /AH for 4 cells in series.

That's a couple thousand dollars, before shipping, interconnections, BMS, and housing.



john61ct said:


> Cheapest quality deep cycle **FLA** is $1 / AH.


That would be at 12 volts, not single-cell, right? I assume that the expected $0.85/ AH is for a single cell (or parallel group of cells), not for a stack of them to reach 12 volts.


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## sportcoupe (Oct 19, 2010)

I should have clarified the lithium type upfront. I am looking at LFP (lifepo4) cells. I have experience building HV packs for golf carts using leaf modules. They are not conducive to 12v usage because of their 2p2s module. 

Also, the "expected" $0.85/ AH is for a single cell, not the desired whole pack. With just quick searches, I found 400AH LFP cells between $1/ AH and $1.30/ AH. I don't know shipping for just four cells, it could be high.

I won't use FLA, although cheap they are. I don't want to build a sealed enclosure for the gassing smell and they take up a lot of space.

I considered AGM. No gassing problem and they can be side mounted but space is still needed. If you compare usable AH from AGM to LFP, the LFP wins easily.

Drop-in 12v lithium batteries (battleborn, etc,...) are still very expensive. I bet I can build a LFP pack much cheaper.

Use will be a house battery for a campervan conversion. Sort of RV I guess. Think of a DIY Class B RV. I want power abailable and a 12v 400AH pack would do nicely. 600AH would be even better but it's even more money and cells.


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## john61ct (Feb 25, 2017)

CALB 180s would be my reco.

Don't fall for no-name.

What is your location?


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## sportcoupe (Oct 19, 2010)

I'd need eight CALB 180's and it would be short of 400AH. 

The cells I'm looking at are LFP 400AH made by GBSystem. About $1/ AH plus shipping.

I am in Savannah, GA


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## brian_ (Feb 7, 2017)

john61ct said:


> CALB 180s would be my reco.


If you're using CALB cells, why not CALB 400 for the simplest configuration?


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## brian_ (Feb 7, 2017)

sportcoupe said:


> Drop-in 12v lithium batteries (battleborn, etc,...) are still very expensive. I bet I can build a LFP pack much cheaper.


I agree. These off-the-shelf batteries incorporate an internal BMS, and combining four of them (100 Ah @ "12V" is typical) results in an excessively complex BMS and housings. Also, they are marketed to people who have no clue what is inside, just want a drop-in replacement for common 12 V lead-acid batteries, and are willing to pay a lot for increased performance.



sportcoupe said:


> Use will be a house battery for a campervan conversion. Sort of RV I guess. Think of a DIY Class B RV. I want power abailable and a 12v 400AH pack would do nicely. 600AH would be even better but it's even more money and cells.


Any RV conversion of a van is a Class B. 400 Ah (@ "12V") is huge capacity for Class B (similar to four "golf cart" batteries), but some people do it, especially if they are planning for refrigeration and cooking to be done electrically. RoadTrek offers even larger in their optional EcoTrek systems.

In a larger motorhome the battery can go under the floor, but in a van it will likely end up on top of the floor, under the bed. Please enclose and vent it appropriately.


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## sportcoupe (Oct 19, 2010)

It’s only Class B of built by a RV manufacture and titled Class B. Self conversions are still just vans. 😁

Yes 400AH is large, I can afford it and the power will be used. Heck, one day I may add another 400AH in parallel for super power. 

CALB 400AH look to be around $500 each. The GBSystem 400AH are $400 each. Much better deal for same capacity and similar specs. Anyone seen 400AH cells for a better price?


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## sportcoupe (Oct 19, 2010)

brian_ said:


> In a larger motorhome the battery can go under the floor, but in a van it will likely end up on top of the floor, under the bed. Please enclose and vent it appropriately.


I am converting a small van, under 21 feet length. I still will probably install house battery under the floor. Really depends on the house battery I end up getting.


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## brian_ (Feb 7, 2017)

sportcoupe said:


> I am converting a small van, under 21 feet length. I still will probably install house battery under the floor. Really depends on the house battery I end up getting.


Great if you can do it, but good luck with that. The traditional rear-wheel-drive vans fill much of the underfloor space with propeller shaft, fuel tank, and exhaust system... and the remaining space is broken up by the frame and body structure. In what's left, you would ideally want to mount the fresh water tank, grey waste tank, possibly black waste tank, maybe generator, perhaps furnace and/or water heater... and the battery. The Ram ProMaster (Fiat Ducato) is front-wheel-drive and puts the fuel tank under the front seats, so it's a bit better for usable space underneath. What van are you planning to use?

It's easier to build fluid tanks (fresh and waste water) to conform to the available spaces under the floor than to package large rigid blocks of cells to fit.


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## brian_ (Feb 7, 2017)

sportcoupe said:


> It’s only Class B of built by a RV manufacture and titled Class B. Self conversions are still just vans.


No, the classes are just descriptions of recreational vehicle configurations. Lots of people have built Class C motorhomes, and they're still Class C motorhomes, not just trucks. But it's yours, so I suppose that you can call it what you want. 

By the way, the most impressive home-built Class C that I've seen is shachagra.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> Great if you can do it, but good luck with that. The traditional rear-wheel-drive vans fill much of the underfloor space with propeller shaft, fuel tank, and exhaust system... and the remaining space is broken up by the frame and body structure. In what's left, you would ideally want to mount the fresh water tank, grey waste tank, possibly black waste tank, maybe generator, perhaps furnace and/or water heater... and the battery. The Ram ProMaster (Fiat Ducato) is front-wheel-drive and puts the fuel tank under the front seats, so it's a bit better for usable space underneath. What van are you planning to use?
> 
> It's easier to build fluid tanks (fresh and waste water) to conform to the available spaces under the floor than to package large rigid blocks of cells to fit.


You are making a lot of assumptions in my van build. Let's stick to creating a 400AH lifepo4 house battery for this forum.

I'm still looking for the best deal source, most likely direct from China. I can wait months for the house battery as I know it's long lead time due to surface shipping, slow boat from China saying is real this time. I'm still scanning Alibaba and Aliexpress for a distributor that would deal in low quantity orders.


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## john61ct (Feb 25, 2017)

brian_ said:


> If you're using CALB cells, why not CALB 400 for the simplest configuration?


Two strings give redundancy without buying a spare cell


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## brian_ (Feb 7, 2017)

john61ct said:


> Two strings give redundancy without buying a spare cell


Are you suggesting paired cells, four pairs in series, or two four-cell strings in parallel? Two strings would double the BMS complexity.

RVs rarely have battery redundancy, although lithium cells without widespread availability might make that wise. sportcoupe was explicitly looking for the minimum number of cells.


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## sportcoupe (Oct 19, 2010)

Correct, four 400Ah cells in series. Simple. If I used eight 200AH cells (4S2P), it's not redundant, it's just more wiring and additional BMS. If 400AH cells are available, that's what I'll use unless there is a spectacular deal on 200AH cells.

To be redundant, I'd have to add a second house battery that came on line when the first one was drained. I don't know why you'd do that.


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## Sunking (Aug 10, 2009)

You do not need a BMS for a 4S system. Would be complete waste of money as is using lithium in your application.


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## Sunking (Aug 10, 2009)

john61ct said:


> Two strings give redundancy without buying a spare cell



Who cares and why pay up for it? EV is different, loose a cell in a single string, and you are stranded. Loose a cell in a RV house battery is no big deal.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> You do not need a BMS for a 4S system. Would be complete waste of money as is using lithium in your application.


I can see the logic in not using a BMS in a 4S system but it would be easy and ensure pack stays balanced. A BMS that small is cheap.

I respectfully disagree that lithium is a waste of money for a RV house battery. To get the same 400AH capacity, you would need almost 800Ah in FLA and deal with the off gassing, maintenance and smell. I won't even get into the space required for a 800AH FLA 12v system.


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## john61ct (Feb 25, 2017)

If you treat LFP well, it will last for decades.

In the long run cheaper than good deep cycling lead.

No dropping acceptance rate as SoC climbs, no need to get to Full, little voltage sag at high currents, all are pretty compelling.

But if you murder the bank - which is not hard for noobs - you are a **lot** more out of pocket.


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## brian_ (Feb 7, 2017)

Sunking said:


> You do not need a BMS for a 4S system. Would be complete waste of money as is using lithium in your application.


It's the same problem as with 96S, just in a smaller scale. Even a single lithium cell needs to be protected from undercharging and overcharging, and even in four cells one can get out of balance. Are you suggesting four voltmeters and manual monitoring? Keep in mind that in an RV there is no driver watching gauges while the battery is being discharged.

As for lithium being a "complete waste of money", the set of four to six GC2 lead-acid batteries which would be the alternative (depending on how much of the battery's capacity that you judge to be usable) is very heavy, and that is a concern for small RVs.


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## sportcoupe (Oct 19, 2010)

I contacted a distributor for CALB. They informed me the CALB 400AH cells were discontinued.

GBS 400AH cells are only available direct from China, USA distributors don't stock them.

Any other options for 400AH cells? I don't want to parallel cells to keep it simple.


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## john61ct (Feb 25, 2017)

Winston, imported from Europe if you don't know reliable sourcing from China. May also be available as Voltronix?

Maybe even up to 1000A cells


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## sportcoupe (Oct 19, 2010)

Correct, I do NOT know reliable source from China. I see cheap prices but when you request quote they either can't support you or DOUBLE the price to cover "fees".

Do Winston cells have a reliable source? I suspect they are more expensive...

1000AH? I'd love 4 of those bad boys. $$$$$


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## Miaplacidus82 (Oct 11, 2018)

I'm still looking for the best deal source, most likely direct from China.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Do Winston cells have a reliable source? I suspect they are more expensive...


https://www.ev-power.eu/Winston-40Ah-200Ah/

Pretty sure Voltronix in the US is rebranded Winston/Thundersky.

EV West


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## JoeG (Jul 18, 2010)

I have purchased from Batteryspace.com 40Ah LiFePo4 cells and they delivered what they promised. They also list a 400Ah cell here, https://www.batteryspace.com/lifemn...-2v-400ah-1280wh-2c-rate---un38-3-passed.aspx

Not cheap though, about $1.85 an Ah plus shipping


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## sportcoupe (Oct 19, 2010)

I have yet to find the rumored $0.85/ Ah except for the very questionable direct from China sites (Alibaba, Ali Express, etc...).

I have found 400AH cells for $1.24/ Ah plus shipping and will probably go with that if prices don't come down. 

For the gotta have the biggest folks, Winston has 700Ah cells for the same $1.24/Ah and mighty HUGE 1000Ah cells for even cheaper, $1.19/Ah. Both plus shipping.


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## john61ct (Feb 25, 2017)

No way bare cell prices coming down, not from quality makers.

Anything much cheaper will be factory seconds or even counterfeit scams.

An improved high-volume supply chain will just mean a bit cheaper shipping costs and added value like higher trust levels, native-English CS, local warranty returns, matched capacity or even pre-balanced sets etc without paying a lot more.

Which would of course be fantastic.

Now, quality high-current "open hardware" BMS at nominal 12V, that would be a likely place to see prices drop so DIY can have the same protections as say a Victron or Lithionics system without being an engineer reinventing the wheel every time.

Anyone know who makes those BatterySpace prismatics?


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## Sunking (Aug 10, 2009)

sportcoupe said:


> I can see the logic in not using a BMS in a 4S system but it would be easy and ensure pack stays balanced. A BMS that small is cheap.


The BMS will never turn on, last thing you want to do is fully charge a Lithium battery which is required for a BMS to even turn itself on. Just float them at 13.8 volts. and set your Inverter to trip off-line at 11.5 volts. 



sportcoupe said:


> I respectfully disagree that lithium is a waste of money for a RV house battery. To get the same 400AH capacity, you would need almost 800Ah in FLA and deal with the off gassing, maintenance and smell. I won't even get into the space required for a 800AH FLA 12v system.


 I have no clue where you came up with that? A good higher end FLA like a Trojan Industrial or a Rolls 4000 or 5000 series has the exact same usable capacity of 80% capacity. However will live a lot longer than any Lithium battery. You would have to be pretty gullible to think otherwise. CALB, Winston, GBS if you could get a Chi-Com manufacture to honor a 1 year warranty tells you how long they will last. Trojan Industrial has a 10 year warranty with first 3 years full replacement plus 7 years prorated for 10 year total. Rolls 4000 and 5000 same 10 year warranty Trojan offers. Either cost 1/3 what Lithium cost and will last 5 times longer.

In the last 8 years I have done about 100 Off-Grid Solar Solar Systems where the client insisted on using CALB and GBS batteries in 24 and 48 volt configurations up to 1000 AH. All have been replaced with Lead Acid because the Chi-Com cells just do not last. None of them over discharged or over charged. They just loose capacity and internal resistance goes way up in a year or less. That is why DIY EV guys no longer use Chi-Coms.


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## brian_ (Feb 7, 2017)

Sunking said:


> A good higher end FLA like a Trojan Industrial or a Rolls 4000 or 5000 series has the exact same usable capacity of 80% capacity.


The general public's rule-of-thumb is to not discharge lead-acid batteries below 50% SOC. There's nothing magic about this level, but it looks reasonable given the shape of the cycle life versus discharge level curve, and even Trojan quotes cycle life at this level (3600 cycles at 50% discharge). What most people miss is that even if discharging to 80% depth of discharge (20% SOC), expected life is still substantial, if only half as long as at 50% (the same Trojan with 3600 cycles @ 50% is rated for 2000 cycles @ 80%). In an RV, how many years does it take to cycle the batteries two thousand times?








(from Trojan's Solar Industrial Line Flooded product page)

How many cycles are the LiFePO4 cells expected to last?



Sunking said:


> ... set your Inverter to trip off-line at 11.5 volts.


I think some of the reason for caution in deeply discharging lead-acid batteries is that they are routinely used (particularly in RVs) with no system protecting against accidental excessive discharge. An automatic shutoff is typically considered necessary with lithium, and would be wise for anyone pushing the limits of even lead-acid batteries. However, this is not just about an inverter: an RV typically uses 12 V DC power for lighting, ventilation, the furnace fan, controls for all appliances (furnace, water heater, refrigerator), and pumping water... so the protective shutdown (or at least a warning) should be for all loads, not just the inverter and whatever it powers.


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## LiFeP04_RV (Sep 10, 2016)

Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay:

https://www.ebay.com/itm/Lot-of-8-p...377409?hash=item2ab7fc1501:g:NAcAAOSwaB5Xtx0m

We use 16 of these, they have provided us good service for approximately 3 years, they have been discharged to 20% many times with no noticeable decrease in capacity and they power everything including the air conditioning (for about 2 hr continuously) on our Roadtrek. 

Yes it was painful to series-parallel them and you will not get 400 amp hours out of 16, but they actually fit the space that we had extremely well.

The seller provided extra tie straps upon request which made it a lot easier to do the series paralleling. 

BTW, if you plan on camping in colder temperatures definitely either heat the batteries or place them in your heated area. I learned this the hard way in 2 builds and had to add extra heat for both.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> The BMS will never turn on, last thing you want to do is fully charge a Lithium battery which is required for a BMS to even turn itself on. Just float them at 13.8 volts. and set your Inverter to trip off-line at 11.5 volts. .


That's exactly what I was thinking for a non-BMS 4S pack. Seems to work well for others.







sportcoupe said:


> I respectfully disagree that lithium is a waste of money for a RV house battery. To get the same 400AH capacity, you would need almost 800Ah in FLA and deal with the off gassing, maintenance and smell.





Sunking said:


> I have no clue where you came up with that?


 
You disagree that FLA's have off-gassing, maintenance and smells? 
You can't argue that discharging past 50% will shorten the life of a FLA. 






Sunking said:


> A good higher end FLA like a Trojan Industrial or a Rolls 4000 or 5000 series has the exact same usable capacity of 80% capacity. However will live a lot longer than any Lithium battery.


 
I just saw the Rolls have a 7 year warranty, that is very impressive. I haven't heard of them till now. I have experience in traditional Trojan 12v FLA and they only provide ~3 years service in golf carts. 

While FLA are proven technology, I'd much rather prefer a sealed battery in my camper. I see Trojan has high capacity 250Ah 12v AGM's but they only have a 1 year warranty. Any thoughts on a quality AGM with at least 250Ah size and a great warranty? I could parallel two for a 500Ah pack in the future.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> You disagree that FLA's have off-gassing, maintenance and smells?


It your batteries are gassing excesively would tell you the voltage is set too high





sportcoupe said:


> You can't argue that discharging past 50% will shorten the life of a FLA.


I never said anything otherwise now did I? What I said is both have the same usable capacity at 80% DOD. At 80% DOD, which would be a very rare event unless the owner is DIY and clueless, Trojan Industrial line still has twice the cycle and calendar life than Chi-Com LiFeP04.


I have designed around 50 RV systems for Tree Huggers that want to use solar, and some who listen and use other means of recharging. You size the battery for 3-day run time which is easy.This gives you 2-day Run Time with no sun or driving to recharge. Only a fool would size their battery for 1-day Run time. FWIW a fixed off-grid system uses 5 day reserve capacity to get that 20% DOD for maximum cycle life. Yes I get questioned about only using a 3-day reserve on RV's, but here is the deal, it is no big deal. A home system is used every stinking day, but not an RV which is part time use, and the batteries will last longer than stationary systems. 



As for charging, well that is easy. Yep some people think solar will work, wrong. How many people are stupid enough to park their RV where in full sun with no shade issues from sun rise to sunset? Seen lots of folks spend a few thousand dollars on solar to charge their batteries with solar only to find out they still need a generator or shore power. Smart money is use a small wattage solar system as supplement, but rely on a $75 Electronic Battery Isolator and use the engine alternator to do the heavy lifting and charging. If they are parked more then two days will use a generator and charger. 






sportcoupe said:


> I just saw the Rolls have a 7 year warranty, that is very impressive. I haven't heard of them till now. I have experience in traditional Trojan 12v FLA and they only provide ~3 years service in golf carts.


Rolls is to Rail Road and Marine as Trojan is to Golf Cart and Floor Sweeper machines. They have been around a long long time. The 5000 series carries 10 year warranty. Both Trojan and Rolls are 100% made in the USA.


You are right golf cart batteries last about 3 years as designed. Golf courses do not own golf carts, they lease them with 3 year contracts. But you are talking Trojan entry level Signature Series, not the Premium or Industrial lines. 








sportcoupe said:


> While FLA are proven technology, I'd much rather prefer a sealed battery in my camper. I see Trojan has high capacity 250Ah 12v AGM's but they only have a 1 year warranty. Any thoughts on a quality AGM with at least 250Ah size and a great warranty? I could parallel two for a 500Ah pack in the future.



AGM has its place, a niche application place you really need to justify for the added expense. AGM cost twice as much and only last half as long as FLA. So in the end you are talking 400% higher cost. You would be better off using a decent LFP battery. AGM is great for locations:


1. Unusual installation orientation like on their side.
2. Where very high charge and discharge rates will be encountered.
3. Spills cannot be tolerate like aircraft for which AGM was invented for.
4. Extreme cold of -40 and lower.


Sounds like you might be stuck inside a 12 volt toy box. Last thing in the world you want to do is install Pb batteries in parallel. Guaranteed to cut cycle life in half. That is why battery manufactures suggest parallel installations. Smart money is if you need 500 AH, then buy 500 AH batteries. They will not be 12 volts, they will be 6 or 4 volt batteries wired in series. Say a pair of *Rolls S-550* or Trojan *SIND-06-610*. Both Trojan and Rolls have had their batteries tested by 3rd party testing agency and put through IEC 61427 an real world cycle life test very few manufactures would ever make available to the public because it would make them look very bad. IEC61427 on Trojan Industrial Line-Up is 17 year cycle life and Rolls 5000 series to be at 15 years.


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## Sunking (Aug 10, 2009)

LiFeP04_RV said:


> Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay:


Completely meaningless.You do NOT PRICE BATTERIES based on AH because it tells you NOTHING. Your base battery cost on Watt Hour Capacity.

Which battery cost less?

1. LFP 100 AH cell = $125
2. LMO 100 AH cell = $140

By your logic the LFP cell is less expensive and is dead wrong. The LMO cell is less expensive. 

Battery Watt Hour Capacity = Nominal Voltage x Amp Hours

100 AH LFP = 3.2 volts x 100 AH = 320 Watt Hours for 39-cents per WH. 
100 AH LMO = 3.8 volts x 100 AH = 380 Watt Hours for 37-cents per WH.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> .....




Dereck,


Thank you for valuable feedback. I read your posts at LEAST three times so they sink in (that almost sounds like Sunking, LoL).


You have me completely rethinking my plans based on the facts you provide.


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## boekel (Nov 10, 2010)

Sunking said:


> Completely meaningless.You do NOT PRICE BATTERIES based on AH because it tells you NOTHING. Your base battery cost on Watt Hour Capacity.


unfortunately that's how LFP cells are usually priced to compare them...
Luckily other chemistry's are more likely to be priced per kWh


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## brian_ (Feb 7, 2017)

sportcoupe said:


> You can't argue that discharging past 50% will shorten the life of a FLA.


It's as if we didn't already have this discussion...

There's nothing special about the 50% DoD (Depth of Discharge) or SoC (State of Charge) level. Did you look at that graph in post #34? The trade-off between life (in cycles) and depth of discharge is a continuous function - you can pick any DoD for which you are willing to live with the cycle life.


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## john61ct (Feb 25, 2017)

And it's an average. Few setups beep at a fixed SoC and start charging on demand


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## brian_ (Feb 7, 2017)

Sunking said:


> Sounds like you might be stuck inside a 12 volt toy box. Last thing in the world you want to do is install Pb batteries in parallel. Guaranteed to cut cycle life in half. That is why battery manufactures suggest parallel installations. Smart money is if you need 500 AH, then buy 500 AH batteries. They will not be 12 volts, they will be 6 or 4 volt batteries wired in series.


Normal RV practice for capacities larger than is practical with a single battery is to use two 6V batteries in series, most commonly of the GC2 size simply because deep-cycle batteries in this size are readily and economically available. Yes, some parallel 12V two-battery installations are used (I have one in a trailer), usually to be able to use cheap "RV/marine dual purpose" 12V batteries.

For capacity beyond about 200 Ah @ 12V, the typical practice is to use four 6 V GC2 batteries. While just two large 6V batteries in series would be ideal, most builders, owners, and maintainers don't want to deal with the weight of a battery large enough to handle half of this total capacity in a single box; that Trojan SIND-06-610 weighs 100 kg. Three 4V batteries in series is a rational way to handle this, but it's hard to find a 4V battery as small as 500 Ah, and even if you find one it's going to be at least 50 kg.


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## Electric Forklift Guy (Dec 13, 2012)

Dont overthink this.

1. Lithium batteries freeze easily and are expensive

2. Lead chemistry batteries are HEAVY about 400 pounds.

If you plan to use this battery when the weather drops below 40F you are pretty much stuck with FLA or AGM

If weight is the main issue , you need lithium.

Personally I would go with a higher voltage battery running a DC to DC convertor so I could put a bunch of small cells in series.

You can buy a 24 Volt , 200 AH battery pack with a steel case and built in charger (Standard battery pack for electric pallet jacks) for about $2000 if you go with lead

If you decide on lithium , a 48 volt pack with 100 AH cells would provide the same power and it's easier to find 100AH cells.


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## brian_ (Feb 7, 2017)

Electric Forklift Guy said:


> Personally I would go with a higher voltage battery running a DC to DC convertor so I could put a bunch of small cells in series.


This is one way to reduce problems of paralleling, but if you're building a pack from individual cells is that really a problem? Production EVs normally parallel at least two cells at the lowest level, and those using tiny 18650 cells parallel dozens of them at the lowest level.

The DC to DC converter would provide a nicely regulated output voltage, but it would also add conversion loss. A similar problem would exist on the charging side, with none of the usual RV charging sources able to charge the battery without the cost and efficiency loss of a voltage conversion step.

I have considered the idea of a higher-voltage RV battery, but specifically to make 120 V AC integration better in a motorhome: with a nominal battery voltage over the peak-to-peak voltage of 120 VRMS, the inverter could be very simple and efficient, the raw 3-phase output of a typical "inverter" type generator could be used by a rectifying charge controller without an unnecessary 60 Hz step, and a regenerative braking system could produce several kilowatts without excessively high current. All of this is probably viable only with substantial custom component construction.


----------



## john61ct (Feb 25, 2017)

Electric Forklift Guy said:


> Lithium batteries freeze easily
> …
> If you plan to use this battery when the weather drops below 40F you are pretty much stuck with FLA or AGM


Nope.

Cannot **charge** (much) below freezing, 

nothing to do with "freezing"

but discharge is fine down to far below

Storage often even lower no problem.

See the spec sheets for Winston, CALB etc


----------



## Sunking (Aug 10, 2009)

boekel said:


> unfortunately that's how LFP cells are usually priced to compare them...


If you are comparing LFP to LFP with the same nominal voltage, then you can compare Amp Hour cost.


----------



## Sunking (Aug 10, 2009)

brian_ said:


> I have considered the idea of a higher-voltage RV battery, but specifically to make 120 V AC integration better in a motorhome:


Well I am hear to tell you is it is common practice to run at 24 volts, and a few 48 volt systems. But be warned going to a higher voltage eliminates your prime power source, the 12 volt alternator to recharge your batteries whenever engine is running. Pretty much means you would need a generator.


----------



## brian_ (Feb 7, 2017)

Sunking said:


> Well I am hear to tell you is it is common practice to run at 24 volts, and a few 48 volt systems. But be warned going to a higher voltage eliminates your prime power source, the 12 volt alternator to recharge your batteries whenever engine is running. Pretty much means you would need a generator.


In fixed solar installations, sure, but in an RV? There are lots of 24 V vehicles (mostly military), but I've never heard of anyone doing that in an RV - do you have links to any RV which comes this way, or a company converting them? I wonder what they use for conversion from battery voltage down to 12 V (nominal).

In a quick search I only found a single example of a 24 V RV system (DIY RV Solar), and that was a poor choice driven only by availability of a cheap inverter/charger.

I already identified the issue with charging from the engine, which could be done with a DC-to-DC charger.

I considered 48 V, but I don't think I would bother with 24 V or 48 V, which for an RV doesn't seem high enough to provide much benefit to offset the hassles of being at anything other than 12 V.


----------



## john61ct (Feb 25, 2017)

Yes, true.

Savings in wire gauge rarely offsets cost of voltage conversion gadgetry.

But for those with some good reason I can't imagine, 24V and even 48V alternators do exist, can be custom wound.

Maybe on a boat using electric propulsion or very big winches, bow thrusters etc


----------



## Sunking (Aug 10, 2009)

brian_ said:


> In fixed solar installations, sure, but in an RV?


Sure, but you got caught in a 12 volt box. There are two applications that demand 24 volts and once in a while 48 volts.


Any solar application with 1000 watts or more require 24 volts. IMO anything above 500 watts. That has to do with economics, efficiency, space, and safety. The largest practical Charge Controllers you can find today are 80 amps. At 12 volt battery input limit is 1000 watts. Any higher requires two expensive controllers. At 24 volts only requires a 40-Amp Controller. A good 80 amp controller will cost you $600 and up. A good 40 to 45 amp controller can be had around $300 to $400. Savings continue to wiring because you use smaller wiring. 

The second application is perhaps something you have over looked. Class A Motor Homes/RV with diesel engines and 24 volt electrical systems. Like a Tour Bus Conversion with all the Bells and Whistles.


Either way just use a good Buck DC to DC Converter for 12 volt gadgets and gizmos if needed. Physically makes no difference if 12, 24, or a rare 48 volts is used in an RV. From a practice POV all the voltages are treated the same being low voltage below 50 volts. Only real issue is sacrifices you may encounter using 24 volts in a 12 volt vehicle. The RV market makes a lot of 12 volt gizmos and gadgets you may have to give up, or provide a converter for. The deal breaker IMO is loosing the engine alternator as a primary power source. However people who use solar have no fear of loosing the alternator. They just use a genny or do without for times of clouds/rain.


----------



## LiFeP04_RV (Sep 10, 2016)

Sunking said:


> LiFeP04_RV said:
> 
> 
> > Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay:
> ...


OP used a/h so I used it. Sorry it offended you. 

I personally would not use LMO (lithium manganese oxide) in an RV, especially at 12V, not compatible with typical alternator voltages. Also too prone to thermal runaway, especially if not managed.


----------



## brian_ (Feb 7, 2017)

Sunking said:


> The second application is perhaps something you have over looked. Class A Motor Homes/RV with diesel engines and 24 volt electrical systems. Like a Tour Bus Conversion with all the Bells and Whistles.


That's a good example of where it would make sense. Those are a tiny fraction of the RV world (I don't think even a normal diesel Class A would be 24 volt).



Sunking said:


> The deal breaker IMO is loosing the engine alternator as a primary power source. However people who use solar have no fear of loosing the alternator. They just use a genny or do without for times of clouds/rain.


Sure, but we're discussing an RV, and one that is unlikely (I would guess) to have a massive solar installation and will almost certainly have a 12 volt automotive charging system. Carrying a generator just because the system wasn't properly set up to charge from the vehicle would be silly, and doing without power is not reasonable.


----------



## john61ct (Feb 25, 2017)

48V as a House bank makes little sense to me, would need to run a separate 12V bank for normal devices, converters are crazy expensive. Maybe if you want an all-mains setup, run everything off a huge 48V inverter?

But no, silly to give up alt charging when it's already there.

Even 24V to me violates KISS. SCs are not a major expense overall, and wiring runs are one time, don't break like conversion gadgets.

From a practical economics POV, only if the alt is 24V already, or if really needed for important high-current devices, maybe say winches?


----------



## brian_ (Feb 7, 2017)

john61ct said:


> But for those with some good reason I can't imagine, 24V and even 48V alternators do exist, can be custom wound.
> 
> Maybe on a boat using electric propulsion or very big winches, bow thrusters etc


24 volt alternators are for vehicles that are 24 volt (military, maybe still some large commercial vehicles). 48 volt? Who knows... I don't know what is used on boats. I checked a random bow thruster manufacturer, and their smaller units are 12 volt while the largest are 24 volt.


----------



## john61ct (Feb 25, 2017)

LiFeP04_RV said:


> I personally would not use LMO (lithium manganese oxide) in an RV


Yes, LFP is the only safe non-lead chemistry for any small space / mobile House bank use case. And new big prismatics, not a science projects of cylindricals or ex-EV banks.


----------



## john61ct (Feb 25, 2017)

Completely agree AGM are poor value, use only if install space requires, or money not an issue.

Yes Rolls / Surrette is fantastic. But only FLA. Their AGM are relabeled chinese.



Sunking said:


> It your batteries are gassing excesively would tell you the voltage is set too high


Normal usage to vendor charging specs produces some gassing.

But that has never been an issue for me even in a tightly sealed living space, long as good controlled ventilation is in place. Put the exhaust port in the bank area.

Yes, some people are hypersensitive or dislike the smell, so box the bank up and vent to the outside, NBD.


> Chi-Com LiFeP04

Please define, and link to LFP that you consider better quality wrt longevity.


> Only a fool would size their battery for 1-day Run time

True for lead maybe, but not if ICE recharging on demand is convenient, and solar there for the long tail. LFP makes the solar redundant.


> not an RV which is part time use

millions live mobile full-time


> You are right golf cart batteries last about 3 years as designed. 

Well coddled, even just-decent GCs can go 6-7 years and still be above 70% SoH.


----------



## john61ct (Feb 25, 2017)

brian_ said:


> This is one way to reduce problems of paralleling, but





Sunking said:


> Last thing in the world you want to do is install Pb batteries in parallel


Finally!

I think

> Guaranteed to cut cycle life in half

is overstating the case though, for just a few paralleled strings.

I personally like / need two strings for redundancy, in critical and/or remote full-time use cases.

But it is indeed my understanding, that going **past 3-4 strings**

(not of single cells paralleled to get higher AH, but of multiple-unit strings)

will result in balancing issues and shorter overall cycle lifetimes.

Can you confirm that is the case? Are there other issues? Can you concisely describe **why** paralleling too many strings is bad?

Any links or cites to back it up?

Would be greatly appreciated


----------



## john61ct (Feb 25, 2017)

Electric Forklift Guy said:


> You can buy a 24 Volt , 200 AH battery pack with a steel case and built in charger (Standard battery pack for electric pallet jacks) for about $2000 if you go with lead


$400 for local pickup Deka GCs, gets more AH, and plenty left over for a top-notch 40A marine charger, panel kit and a genny.


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## john61ct (Feb 25, 2017)

LiFeP04_RV said:


> Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay
> https://www.ebay.com/itm/Lot-of-8-p...377409?hash=item2ab7fc1501:g:NAcAAOSwaB5Xtx0m


Any idea of the actual maker?

AliExpress link to compare?


----------



## john61ct (Feb 25, 2017)

brian_ said:


> How many cycles are the LiFePO4 cells expected to last?


From top-notch vendors, makers like 

Systems: OceanPlanet (Lithionics), Victron, MasterVolt, Redarc (Oz specific?)

Bare cells: ​Winston/Thundersky/Voltronix, CALB, GBS, A123 & Sinopoly

If I have missed any sold to consumers, please let me know.

Their spec'd cycle lifetimes appear to actually be very conservative, perhaps building in some expected abuse.

Very much unlike the lead batt industry, where even perfect coddling rarely matches claimed lab performance, marketing departments have too much influence vs engineering.

But IMO, following the vendor LFP charging specs for day to day usage is IMO inherently abusive, compared to avoiding the voltage shoulders.

With the latter, looks like decades' daily use is possible, certainly 3-5x their lifetime estimates,

if well coddled, no big mistakes, and in a gentle House cycling use case. It is possible that calendar lifespan will end up being more influential than # cycles.

Kindest explanation is, longevity is not their primary goal, violent-currents military and EV usage is the assumption for their testing and research.


----------



## LiFeP04_RV (Sep 10, 2016)

john61ct said:


> LiFeP04_RV said:
> 
> 
> > Not quite $0.85 per amp hour but the cells we have are about $0.875 per amp hour now on eBay
> ...


I think CALB. The aluminum case is hot like the CALB CAM80, dimensions are identical.


----------



## Sunking (Aug 10, 2009)

brian_ said:


> Sure, but we're discussing an RV, and one that is unlikely (I would guess) to have a massive solar installation and will almost certainly have a 12 volt automotive charging system.



Well you would be surprised how many folks use Solar as their primary power source. As long as you keep panel wattages to less than 1000 watts which is the vast majority, 12 volts works just fine. Kicker is and this is the big kicker, if you have an Electronic Battery Isolator and drive at least every 3-days, then solar is just a wasted expense. Most setups I recommend and design only use Solar as a Supplement in the 200 to 400 watt range into a pair of 6-volt batteries wired for 12 volts. If truth be known Solar in that case is just show and tell and actually does not do much. You see this type of setup a lot in RV Rentals and Factor designs. 



Then you have that crowd of tree-huggers who hate anything that uses gas or diesel. They will require a huge system in excess of 1000 watts, and that requires 24 volts or higher. Funny thing is if truth be told off-grid solar is not only 5 to 10 more expensive than buying power, but is also a very heavy polluter and Li batteries make that even worse because they require so much energy to make you never get an EROI. However I could care less, just pay me.


----------



## brian_ (Feb 7, 2017)

Sunking said:


> Well you would be surprised how many folks use Solar as their primary power source.


In fact, I wouldn't be surprised. Lots of people use solar panels rated under 200 watts to meet their needs in travel trailers (when camping in conditions in which they are happy without air conditioning)... typically with about 200 amp-hours (nominal) at 12 volts (nominal) of flooded lead-acid battery capacity. Individual energy requirements and travel conditions vary, of course, and sportcoupe has chosen a higher capacity.



Sunking said:


> As long as you keep panel wattages to less than 1000 watts which is the vast majority, 12 volts works just fine. Kicker is and this is the big kicker, if you have an Electronic Battery Isolator and drive at least every 3-days, then solar is just a wasted expense. Most setups I recommend and design only use Solar as a Supplement in the 200 to 400 watt range into a pair of 6-volt batteries wired for 12 volts...


That's what I was saying. So it seems that we agree that higher-voltage systems appear to be unlikely to be an improvement over 12 volts for the subject of this discussion.


----------



## john61ct (Feb 25, 2017)

And with lead off grid, solar is a necessity for longevity's long tail, no matter how many ICE amps you have available on demand.


----------



## john61ct (Feb 25, 2017)

> a huge system in excess of 1000 watts, and that requires 24 volts or higher

Not "huge" and a 12V setup is fine.

My favorite setup is a ~250W / 40+Voc panel paired with a Victron 75/15, around $120. Super efficient and full-featured, custom setpoints and data logging from my phone.

Add as many such pairs as you like over time to fill the roof or on slideouts, portable folding, whatever.

No need for the panels to match, and each is MPPT optimized for azumith angle or partial shading conditions.

Maybe 80AH avg per day each into the bank, including some days less than ideal conditions. Get 5-6 pairs and run 16k btu aircon off it 

Yes silly I know.

But going to 24V House setup just to save a bit of money on thick wiring or cheaper SCs is sillier.


----------



## Duncan (Dec 8, 2008)

NOT what I have found

I have a 5,000 watt home system that runs on 400v - no battery as yet but it is saving me enough to pay for itself in about 7 years 
In energy terns about 8 months to repay the energy needed

And this is South Island - not a hot place with ZERO subsidies of any kind

I am thinking about a battery - but it will do double duty as a range extender


----------



## john61ct (Feb 25, 2017)

Just a reminder of the OP topic


sportcoupe said:


> I'm looking to make a storage battery for a camper


----------



## Duncan (Dec 8, 2008)

_*I'm looking to make a storage battery for a camper*_

He has ignored the *best advice *of using some EV modules - you guys are all working on the "not worst"


----------



## sportcoupe (Oct 19, 2010)

john61ct said:


> Just a reminder of the OP topic


Correction. Topic is:

*400AH lithium cells? Best price per AH? $0.85/ AH?*

Only a few posts addressed the topic.


----------



## john61ct (Feb 25, 2017)

Because the distribution channels for good quality LFP are very limited, no way to get much below the 5-7x premium over lead.

Lower pricing without compromising quality is IMO a matter of luck with a once-off deal, very rare.

And taking chances with unknown makers or dodgy middlemen, again you may get lucky, but you may not really find out for many years.


----------



## sportcoupe (Oct 19, 2010)

john61ct said:


> Because the distribution channels for good quality LFP are very limited, no way to get much below the 5-7x premium over lead.
> 
> Lower pricing without compromising quality is IMO a matter of luck with a once-off deal, very rare.
> 
> And taking chances with unknown makers or dodgy middlemen, again you may get lucky, but you may not really find out for many years.


I have seen the light, there isn't cheap high capacity lifepo4 cells available yet.

I have been looking at industrial 6V AGM's now for my camper van build.


----------



## Sunking (Aug 10, 2009)

brian_ said:


> Sure, but we're discussing an RV, and one that is unlikely (I would guess) to have a massive solar installation and will almost certainly have a 12 volt automotive charging system. Carrying a generator just because the system wasn't properly set up to charge from the vehicle would be silly, and doing without power is not reasonable.


Brian I think you are overlooking some things. 24 and 48 volt super high efficiency air conditioners like Truckers, Off-Griders and Telecom use. I agree with your POV. If all you need is lighting, some entertainment like a TV/Radio/AV and low power devices 12 volts is just fine. But you have people who insist on electric cooking, refrigeration, and the impossible air conditioning requires a lot of power that a 12 volts is just not capable of doing safely, efficiently, and economically. How many 12 volt EV's do you see. Only a DIY would be that foolish. If the owner refuses to consider using propane for high energy requirements, you have limited your options and have to get creative. 

I have built a many RV systems with both Solar and w/o Solar. Even rented several RV, and the factory units I have rented that have Air Conditioning all have a generator built-in using 24 volt batteries, and a 24 volt heat pump like Truckers use to cool their sleeper cabin. To do that demands higher voltage if solar is used. a 80-amp MPPT controller can only input 1000 watts and that is not enough power for heavy loads. 

Besides anyone who is truly off-grid solar stationary requires a generator to perform routine maintenance and cover their your butt for cloudy spells. Otherwise you spend a lot of days in the dark and destroy your batteries prematurely. 

I agree 12 volts makes the most sense sense for most applications. But when you throw electric cooking, electric refrigeration, and air conditioning into the mix, 12 volts is not going to cut it on solar. 250 MCM and larger copper wire is not practical or cheap. Let alone the experience and tooling to terminate such large cables and compound that with 1-hole Terminals or stabs expecting to have no issues loose connections and burning up with 200 to 400 amps flowing.

Do you wanna talk food trucks now? That is 240/120 territory and higher.


----------



## sportcoupe (Oct 19, 2010)

Sunking said:


> But you have people who insist on electric cooking, refrigeration, and the impossible air conditioning requires a lot of power that a 12 volts is just not capable of doing safely, efficiently, and economically.
> 
> I agree 12 volts makes the most sense sense for most applications. But when you throw electric cooking, electric refrigeration, and air conditioning into the mix..........


Air conditioning is not impossible on batteries. You are limited in how long you can run it. A simple van doesn't need 16k BTU a/c unit, a 5k BTU cools a small van easily. That's 420 watts for a basic 5k BTU unit. It's a lot, but not impossible.

My 12v fridge runs on 40 watts and it only runs 20 mins an hour tops.

I still have to source an efficient microwave that will still pop popcorn.


----------



## john61ct (Feb 25, 2017)

sportcoupe said:


> I have been looking at industrial 6V AGM's now for my camper van build.


in the US market, stick to Lifeline, Odyssey and Lifeline.

Maybe Firefly if PSOC abuse is unavoidable.

I've heard Trojan's getting out of AGM (again), Deka's are meh not really deep cycling, Rolls are outsourced.

But we do you think AGM is required?

Much higher cost per AH per year, much easier to murder, need more precise and higher-current charge sources for lingevity.


----------



## sportcoupe (Oct 19, 2010)

john61ct said:


> in the US market, stick to Lifeline, Odyssey and Lifeline.
> 
> Maybe Firefly if PSOC abuse is unavoidable.
> 
> ...


You said Lifeline twice. What about Full River?

I don't want to deal with messy FLA. I have 140 amps available to charge AGM.


----------



## john61ct (Feb 25, 2017)

Sunking said:


> But you have people who insist on electric cooking, refrigeration, and the impossible air conditioning requires a lot of power that a 12 volts is just not capable of doing safely, efficiently, and economically.


I agree that aircon is very expensive, impractical, so set that aside.

But fridges & freezers, washing machines, dishwashers, induction cookers, microwaves, used judiciously are no problem on a properly sized and designed 12V system.

Of course the robust charge sources need to be there to replace AH used.

In a very high usage scenario, without a 30+' roof, solar is just there for lead's long tail, a genset or big alt is required in the morning for the first few hours.

I've already laid out how solar can be reasonably optimized, one SC per panel if desired.

No one is talking stationary, this is a mobile House supply use case.

Yes heavy wiring, properly crimped is required, par for the course.

200-400A is not going to happen often, obviously efficient versions of appliances need to be selected, 40-80A is normal and only for short times.

The marine world and expedition camping is where this type of setup is routine, the USian RV industry is slapstick / slipshod, Euro and Aussie standard usually much higher.

Yes an alternative is to just go mains current off a big inverter like Victron, but that is not conducive to minimizing AH per day consumption, and add its own expenses, complications and safety issues.


----------



## john61ct (Feb 25, 2017)

sportcoupe said:


> Air conditioning is not impossible on batteries. You are limited in how long you can run it.


Figure an hour of time shifting your genny runtime for each 100AH (50 usable) of capacity dedicated to that function.

Then replacing the AH consumed, much bigger genset required if still running the aircon same time.

Not impossible, but very impractical for most, without a huge rig and spending many thousands extra.

Really tight thick insulation helps.

And of course super-efficient aircon tech, not consumer grade units.

Use propane for your popcorn.


----------



## Sunking (Aug 10, 2009)

john61ct said:


> in the US market, stick to Lifeline, Odyssey and Lifeline.


All good batteries, but there are more of equal quality and better. You mentioned Lifeline made by Concorde but they make even a better AGM in a much wider range of capacities and voltages called Sun Extender. All those mentioned are on the same boat as lithium with a worthless 1 year warranty. Another manufacture of high quality AGM batteries is Fullriver and carry a 7-year warranty. You can hammer them with 80% DOD with no problems in an RV application.


----------



## john61ct (Feb 25, 2017)

sportcoupe said:


> You said Lifeline twice. What about Full River?
> 
> I don't want to deal with messy FLA. I have 140 amps available to charge AGM.


Whoops, Northstar's #3, I try to mix the order up, all 3 are great.

Call them for local dealers, never find in big box, and you do not want to pay for shipping.

Full River is OK, not proven as long in the US as the top three, all the TPPL tech came out of Enersys research funded by US military, rest were spinoffs from that,

and IMO lots of the value eroded by shipping from China.

But fine, if you find it for say 30% cheaper including transportation costs.


----------



## john61ct (Feb 25, 2017)

Sorry typo 

But **why** do you think AGM is required?

Much higher cost per AH per year, much easier to murder, need more precise and higher-current charge sources for longevity.


----------



## sportcoupe (Oct 19, 2010)

I’ve already stated “why” for AGM.


----------



## john61ct (Feb 25, 2017)

Warranty is pretty useless when you have to pay shipping.

Rarely relevant with the top vendors, their QA is tops.

Easy for a noob to destroy a $3000 bank in six months, just learn how to not be that guy.


----------



## john61ct (Feb 25, 2017)

sportcoupe said:


> I’ve already stated “why” for AGM.


OK, not going to re-read

Long as you're aware, your money


----------



## sportcoupe (Oct 19, 2010)

There seems to be three choices for batteries. FLA, AGM, and flavors of lithium. 

Automakers are already switching to AGM. Lithium isn’t readily available in high capacity cells.


----------



## brian_ (Feb 7, 2017)

Sunking said:


> Brian I think you are overlooking some things. 24 and 48 volt super high efficiency air conditioners like Truckers, Off-Griders and Telecom use. I agree with your POV. If all you need is lighting, some entertainment like a TV/Radio/AV and low power devices 12 volts is just fine. But you have people who insist on electric cooking, refrigeration, and the impossible air conditioning requires a lot of power that a 12 volts is just not capable of doing safely, efficiently, and economically.


Some of the air conditioners for trucks run on 120 VAC anyway, and are installed with a dedicated inverter, so the only benefit of higher voltage is smaller cable. Of course in a 24 volt vehicle, 24 volt air conditioning would make sense. Similarly, in a facility where 48 volts is used for other purposes, 48 volts would make sense for air conditioning.

Lots of RV users cook electrically with 120 VAC appliances run by an inverter powered by a 12 volt battery bank.

I agree that if demand is huge, higher voltage is more appropriate. That demand would be unusual in an RV. If it isn't justified by huge demand it can still be used, but it's hard to see a net benefit. I would discuss what sportcoupe might need, but apparently that isn't allowed. 

Mobile compressor-based refrigerators normally operate on 12 VDC, which is no problem because their power demand is small compared to air conditioners and cooking appliances.


----------



## sportcoupe (Oct 19, 2010)

What do you want to know?


----------



## john61ct (Feb 25, 2017)

sportcoupe said:


> There seems to be three choices for batteries. FLA, AGM, and flavors of lithium.
> 
> Automakers are already switching to AGM. Lithium isn’t readily available in high capacity cells.


When you say automakers and AGM, you mean Starter batts right? Totally separate market, little to do with deep cycling batts suitable for House bank usage

1000AH LFP cells are readily available, in fact cheaper than the 400AH other smaller sizes.

No other lithium type is suitable.

But add GEL, also a great choice, Sonnenschein and Deka. Very long lived if coddled, but persnickety about the charge profile.


----------



## brian_ (Feb 7, 2017)

sportcoupe said:


> What do you want to know?


Nothing.



sportcoupe said:


> Let's stick to creating a 400AH lifepo4 house battery for this forum.





sportcoupe said:


> Correction. Topic is:
> 
> *400AH lithium cells? Best price per AH? $0.85/ AH?*
> 
> Only a few posts addressed the topic.


Any discussion of the needs which this battery is to address clearly are off-topic, although discussion of non-lithium solutions is apparently now okay.


----------



## john61ct (Feb 25, 2017)

Yes OP gets to define / change the boundaries of their thread's topics, that's how it works.


----------



## sportcoupe (Oct 19, 2010)

We could move this to a new thread titled "build me a camper van battery" if the mods prefer. 

Or continue to digress from the thread title that has the word lithium in it. 

I need a battery that supports my future camper van electrical needs/requirements as follows.


refrigerator (40 watts)
hot water ??
water pump (on demand)
vent fan (12-30 watts)
LED lights (<20 watts)
device charging (60 watts)
LED TV (40 watts)
gasoline heater (14 watts)
air conditioner (410 watts, occasionally)


----------



## john61ct (Feb 25, 2017)

Then size for the aircon alone, 50AH usable per hour of time shifting desired.

And LFP will eliminate the need for solar.


----------



## brian_ (Feb 7, 2017)

sportcoupe said:


> I need a battery that supports my future camper van electrical needs/requirements as follows...


1. refrigerator (40 watts)
2. hot water [unknown power, possibly as much as 1800 W]
3. water pump [minimal power, typically less than 100 W]
4. LED lights [likely a few tens of watts]
5. device charging [as much as a couple hundred watts if charging a laptop plus multiple mobile devices]
6. small tv [likely less than 100 W]
7. gasoline heater (14 watts)
8. air conditioner (410 watts, occasionally) 

None of those loads appear to be high enough to require currents that would make cabling unreasonable at 12 volts (although the water heater could be significant if large). The air conditioner startup load could be substantial, but still not unreasonably large among RV 12 volt cabling practices. I don't see a reason to consider higher-voltage configurations, whether lead-acid or lithium.

400 Ah @ 12 V is 4.8 kWh . All of those loads together do not appear to be high enough for the discharge rate to be an issue for a battery of this size (regardless of voltage), so this looks like a straightforward energy storage issue, without a power capacity issue. If this were for propulsion power (it's not), this would be equivalent to a battery-electric scenario (energy priority) rather than a hybrid (power priority). That makes nearly any battery chemistry viable.

The use of an electric water heater in an RV with a fueled space heater seems a little unusual, but the vehicle is apparently not diesel, and gasoline-fueled water heaters are rare, if available at all.

I note that there are no cooking appliances listed. Assuming that this is correct, it removes most of the large loads often seen on RV electrical systems; however, there's also this:


sportcoupe said:


> I still have to source an efficient microwave that will still pop popcorn.


Even the smallest available microwave oven has power demand comparable to the air conditioner. As long as there are not multiple large appliances, or they are not run in combination with the water heater or air conditioner, current and power demands should still be non-issues for this size of battery at 12 volts.


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## brian_ (Feb 7, 2017)

john61ct said:


> ... And LFP will eliminate the need for solar.


In a thread of 90 posts, sportcoupe has not mentioned the endurance required, or how frequently driving or starting the van or other engine as a generator might be acceptable, so there is no way to determine whether another charging source such as solar is required. All we know is that 140 A @ 12 V (nominal) is available for charging (and a rational person might guess that's the van's alternator). Since the total capacity of the battery bank is a fixed requirement, and the charging source doesn't change the battery choice, I don't see any relevance to a discussion of a solar system or whether it is required.


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## sportcoupe (Oct 19, 2010)

Hot water isn't figured out yet. I may even forego hot water if an efficient solution isn't available.


Heater might be a Webasto gasoline air top heater unless I find something more cost effective.
https://www.amazon.com/Webasto-Gasoline-Heater-install-9032227A/dp/B01M2ZCWTF


Cooking will primarily be outside van using camp stove. I will need a way to boil water for coffee though without setting up the camp stove 10 times a day.... Forgot to mention that.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> In a thread of 90 posts, sportcoupe has not mentioned the endurance required, or how frequently driving or starting the van or other engine as a generator might be acceptable, so there is no way to determine whether another charging source such as solar is required. All we know is that 140 A @ 12 V (nominal) is available for charging (and a rational person might guess that's the van's alternator). Since the total capacity of the battery bank is a fixed requirement, and the charging source doesn't change the battery choice, I don't see any relevance to a discussion of a solar system or why it is required.




Daily driving with occasional stops of 2-3 days. Starting ICE engine 220A alternator is perfectly acceptable to charge house battery. I have a 140A smart battery isolator to charge if it would be suitable to the house battery.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> Even the smallest available microwave oven has power demand comparable to the air conditioner. As long as there are not multiple large appliances, or they are not run in combination with the water heater or air conditioner, current and power demands should still be non-issues for this size of battery at 12 volts.



I may have to dump the microwave and make popcorn on camp stove


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## john61ct (Feb 25, 2017)

brian_ said:


> I don't see any relevance to a discussion of a solar system or whether it is required.


Because solar is only **necessary** with lead, assuming shore power not often convenient.

Of course if they **want** solar, NP.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Daily driving with occasional stops of 2-3 days. Starting ICE engine 220A alternator is perfectly acceptable to charge house battery. I have a 140A smart battery isolator to charge if it would be suitable to the house battery.


You will need a genny to run the aircon.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Heater might be a Webasto gasoline air top heater unless I find something more cost effective.


 Chinese knockoffs much cheaper, can buy a second for spares.

Espar just as pricey, Planar in between.

I'd look for a water based one, hydronics HWS+space heat, integrate with engine coolant loop.

But not cheap.


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## john61ct (Feb 25, 2017)

brian_ said:


> current and power demands should still be non-issues for this size of battery at 12 volts.


Yes.

The "challenge" with aircon is not the current, but the kwh per day consumption.


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## john61ct (Feb 25, 2017)

Microwave is "doable" off battery if you **really** need it, especially LFP.

But only for short runtimes.

Otherwise use while the genny is running, NP.


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## sportcoupe (Oct 19, 2010)

Besides fuel consumption, what's the difference if I run a small 1000W/800W genny running an inverter/charger or the ICE engine with electronic battery isolator charging house battery?


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## sportcoupe (Oct 19, 2010)

Just to get everything I can think of in one place.

Updated list of electrical needs and wants.

1. refrigerator (40 watts)
2. hot water [unknown power, possibly as much as 1800 W]
3. water pump [minimal power, typically less than 100 W]
4. LED lights [likely a few tens of watts]
5. device charging [as much as a couple hundred watts if charging a laptop plus multiple mobile devices]
6. small tv [likely less than 100 W]
7. gasoline heater (14 watts)
8. air conditioner (410 watts, occasionally)
9. inductive cooking plate (main cooking using camp stove)
10. microwave?
11. roof fan


Camper van usage:

Daily driving with occasional stops of 2-3 days. Starting ICE engine 220A alternator is perfectly acceptable to charge house battery. I have a 140A smart battery isolator to charge if it would be suitable to the house battery.

Aircon will be just to cool down van couple hours before sleeping as needed. Rooftop fan for night sleeping.

Option for small 1000W/800W generator as needed.


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## sportcoupe (Oct 19, 2010)

Concerns on using FLA or AGM:
1. Voltage sag under load falsely hitting low voltage cutoff on inverter reducing house battery usage, even with a fully charged battery. Especially apparent if running microwave or aircon. This wouldn't happen using LFP pack as lithium doesn't experience voltage sag nearly as bad.
2. FLA is messy and I'd rather not deal with it. AGM's can be mounted sideways under van. So can LFP. FLA needs to stay upright of course, and properly vented.

400Ah AGM and LFP can both be discharged 80% without greatly reducing cycles. FLA can't discharge 80% without greatly reducing cycles.

I'm open to AGM or LFP.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Besides fuel consumption, what's the difference if I run a small 1000W/800W genny running an inverter/charger or the ICE engine with electronic battery isolator charging house battery?


Note all the isolator (combiner / VSR) does is stop Starter from going flat, nothing to change the charging.

Running your propulsion engine for many hours per day is silly, very expensive and harmful to its longevity.

Every hour like driving 30-40 miles, just wear and tear.

And alt output will only reach over half rating at much higher rpm than idling.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> 1. Voltage sag under load falsely hitting low voltage cutoff on inverter reducing house battery usage, even with a fully charged battery. Especially apparent if running microwave or aircon. This wouldn't happen using LFP pack as lithium doesn't experience voltage sag nearly as bad.


Well you can wait for guesses or calculate it yourself pretty easily. Most of the AGM batteries you are interested in specify Internal Resistance. For example a *Fullriver DC400-6*; a 6-volt 400 AH AGM specifies Ri = .0016 Ohms. It would take 2 in series for 12 volts thus total Ri = 2 x .0016 Ohms = .0032 Ohms.

From there is simple Ohm's Law *Voltage = Amps x Resistance*. So at say C/4 or 100 amps x .0032 Ohms = .32 volts sag or on a 12 volt system is 2.7% loss. Add another 2 to 3% for cable and connectors and you met a reasonable 5% or less loss.

FWIW broaden your horizons. Go look at one of the 400 AH LFP cells. Just about all of them will list Ri. For 12 volts you would need 4 in series. So multiply the Ri by 4 and tell me if it is higher or lower than the 400 AH AGM. What you are going to gain from that will surprise you because it will be exact opposite of what you are expecting. It will tell you which battery has the higher Specific Power which is expressed as Watts / Kilogram. Put another way how high a C-Rate the battery is capable of. So go see what you find, and tell me what you think. 

Last part of your question regarding FLA. A 6-volt 400 AH battery Ri= will be higher than AGM by about 50% or around .002 Ohms. So they will not have quite a high as a C-Rate. Here is what trips up people. Lithium Batteries C-Rate is a THERMAL LIMIT, not a Performance Specification like all other batteries are measured by. So when you see a CALB rated at say 3C continuous and 10C Burst is a Thermal Limit. At those levels voltage sag will be extreme . Now that you looked up a 400 AH Lithium, do the math at 3C. On the AGM is 1200 amps x .0032 = 3.84 volts.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Voltage sag under load falsely hitting low voltage cutoff on inverter reducing house battery usage, even with a fully charged battery. Especially apparent if running microwave or aircon. This wouldn't happen using LFP pack as lithium doesn't experience voltage sag nearly as bad.


Yes. Counteracted by going bigger AH capacity.

AGM's can be mounted sideways under van. So can LFP

Nope, apparently reduces lifetime, but depends on maker. Risky at least.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> 400Ah AGM and LFP can both be discharged 80% without greatly reducing cycles.


Nope, all three get many times greater lifetime by cycling more shallow.

LFP costs so much and go so many thousand cycles anyway, people don't do it much, although some reserve is good.

AGM is particularly harmed by deeper cycling, IRL much more so than in the lab charts. Combined with PSOC conditions can murder them in a single season easy.


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## Sunking (Aug 10, 2009)

sportecoupe one more design tip. Be real careful with On-Line Wire Size Calculators. They will get you in trouble real quick. Most have a serious FLAW. They only calculate the Resistance required to meet a voltage drop. What they do not do is check their answer to see if it meets any listing agency thermal limits. The Flaw is it will give you too small of aa wire on short distances of 15 to 20 feet or less. Example say you have a 300- amp fuse and want 2% at 10 loop feet, and you will get an answer of 2/0 AWG copper which is too small fine for an EV because that is peak for a few seconds, but not on Power Wiring like an Inverter where loads are continuous. 

My advice to you and anyone interested is use this Table. Find your Fuse or Breaker size, find the Distance. This Table is for Marine which exceeds SAE and NEC standards which means you can sleep at night. Note 300 Amps is not listed. For 300-Aamp Fuse requires a minimum 4/0 AWG Copper at 10-feet loop distance. 



Note wire size is not based on Load Current. Minimum wire requirement is sized to the Fuse or Breaker size feeding the wire. A 3000 watt 12 volt Inverter requires a 300 amp circuit. Good luck with that and 4/0.


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## brian_ (Feb 7, 2017)

john61ct said:


> The "challenge" with aircon is not the current, but the kwh per day consumption.


With this small air conditioner, I agree.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> sportecoupe one more design tip. Be real careful with On-Line Wire Size Calculators. They will get you in trouble real quick.


Thanks for the handy chart.

Wire size calculations in aircraft get even crazier. They of course need voltage, load and length but also add number of wires in bundle, altitude and air temperature of the area they are installed in during flight. 

I've never had to design for more then 15 amps @28v per component though for the systems I integrate into the aircraft.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> FWIW broaden your horizons. Go look at one of the 400 AH LFP cells. Just about all of them will list Ri. For 12 volts you would need 4 in series. So multiply the Ri by 4 and tell me if it is higher or lower than the 400 AH AGM. What you are going to gain from that will surprise you because it will be exact opposite of what you are expecting. It will tell you which battery has the higher Specific Power which is expressed as Watts / Kilogram. Put another way how high a C-Rate the battery is capable of. So go see what you find, and tell me what you think.


LFP Ri is double some AGM batteries. I didn't expect that. 

Fullriver's DC400-6 AGM Ri (0.0016 x2 = 0.0032) is more then double Lifeline's GPL-L16D AGM (0.00068 x2 = 0.00136).


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## sportcoupe (Oct 19, 2010)

john61ct said:


> Yes. Counteracted by going bigger AH capacity.
> 
> AGM's can be mounted sideways under van. So can LFP
> 
> Nope, apparently reduces lifetime, but depends on maker. Risky at least.


Bigger Ah - ok more is better, two Lifeline 6V 400Ah AGM should be fine for voltage sag.

I'm assuming you mean AGM cannot be mounted under van? I don't see a reason why not. Operating temp range is -40F (-40C) to 160F (71C). I would use a steel skid plate (or box) to protect from road debris.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> current and power demands should still be non-issues for this size of battery at 12 volts.





john61ct said:


> Yes.
> 
> The "challenge" with aircon is not the current, but the kwh per day consumption.


Aircon use on batteries will be limited. Max 2 hours a day (maybe?).

Continuous use of aircon, I would connect the small genny or go for a drive to run ICE.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> LFP Ri is double some AGM batteries. I didn't expect that.


I tried to tell you that in PM's but you were not having any part of AGM out performing LFP. Amp Hour per Amp Hour, AGM out performs Lithium with respect to high current. I had to have you discover it for yourself. The math does not lie. 

I will be real honest with you, From what you have stated in this thread, you have not justified an Inverter greater than 1000 watts, 1500 watts is over kill.

If you buy a quality Inverter/charger/ATS of say 1000 watts is continuous power, 2000 peak. So I know 1000 makes you nervous, then go with 1500/3000 which is way more than enough. You wil be able to drop conductor sizes down to 4 or 2 AWG. Remember you are using continuous currents for power and lighting. Not burst currents used in an EV. Different rules and practices for different applications. 

For RV's I use Marine Standards because they exceed NEC and SAE codes. SAE and NEC do not take voltage sag into consideration. Additionally all marine cables are rated for 105 degrees C, wet/ damp, and if you buy Marine Battery Cable you get oil and gas resistance on top of high temp insulation. Marine Battery Cable is Class "I" stranding (super-flex) tinned copper. As good as you can get.


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## john61ct (Feb 25, 2017)

Blue Sea's wire calculator app Circuit Wizard is very thorough, based on ABYC standards.


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## GreenGyver (May 4, 2015)

I'm selling EIG 20AH Lipo cells for $1.50/AH OBO. I have 90 of them. They have all been tested and placed in manufacturers recommended storage voltage (3.8V). I have all the details for them and can printout discharge curves and provide all pertinent information.

I also have about 200 Turnigy 8AH cells. Only about half have been tested and placed into storage.

Let me know if you are interested.
[email protected]


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## john61ct (Feb 25, 2017)

If LiPo, how can they be made to work at 12V for a House bank?


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## Sunking (Aug 10, 2009)

john61ct said:


> If LiPo, how can they be made to work at 12V for a House bank?


 They cannot and is of no concern for scum bag spammer. LiPo is the last thing you want for a house battery or any application requiring long life as LiPo only have roughly 100 cycles in them. LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire. 



They do have a application in EV used as Drag Racers where you can put a very small battery in, just enough for 1 or 2 runs. Some of the new ones claim 100C-Rate for 10 seconds which is all you need for a drag race. A 20 pound battery vs a 1000 pound battery.


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## brian_ (Feb 7, 2017)

None of the lithium chemistries have nominal voltages high enough get away with three cells in series, and even the lowest-voltage common lithium chemistry (LiFePO4) runs at voltages which are too high to be ideal with four cells in series.

I know that my motorhome's furnace is not happy with the charging voltage for my lead-acid batteries; at the peak charging voltage for any lithium battery I would want a voltage regulator between the battery and most loads. I do understand that most people using LiFePO4 in RVs likely just run all loads at battery voltage.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> Wire size calculations in aircraft get even crazier.


Stricter yes like NEC, and for good reason. Easy to hop out of an RV or EV on fire. Not so easy on a plane or boat. 

What many on-line calculators fail to take into consideration is SHORT distances. They assume lengths of 15 feet or longer will be used. Many do not put a Fail - Safe check built-in to see if the wire can safely handle the current or not. 

For example enter in 2-feet, 50 amps, and 3% loss and many sites will come back with 12 or 10 AWG. If you have experience in electrical power know immediately that is dangerous. Sure a 2-feet run of 12 AWG will have the resistance low enough so that the wire only losses .36 volts with 50 amps flowing. Trouble is it becomes a Space Heater and burns the insulation off the wire. You would know instinctively and from experience the minimum safe wire size for 50 amps using 105 degree Insulation is 6 AWG. 


Now some on-line sites are aware of this and have put in the Sanity Check. Some learned the hard way when they got sued and had to replace someones home because they are incompetent pretending to be experts. I know this for fact because it happened on a Forum I moderate. Yes this forum can be sued giving inaccurate or false information.

So remember this. Wire size is based on the OCPD (Over Current Protection Device like a fuse or breaker) feeding the wire. If you have a 20-amp circuit, the minimum wire size must be 14 AWG or larger. Does not matter if the circuit only caries 1 amp. A OCPD only has one purpose and one purpose only, and that is to protect the wire connected to the LOAD side. It has no other purpose. They are *not* there or *capable* of preventing electrical shock or protect the utilization equipment. Only the wire and nothing else. That 3000 watt Inverter at 12 volts requires a 300 amp fuse and a minimum 250 MCM (aka 4/0) copper cable. Voltage drop of a short 10 feet is of no concern operating at 12 volts. On the same lines anything over say 15 feet because a huge concern using toy voltages like 12 and 24 volts. You could find yourself needing multiple parallel pairs of 750 MCM. Use a higher voltage and all that goes away or a lot further out before it becomes a problem. 

Low Voltage + High Power = Fire Hazard. Anything over 500 watts is high power for 12 volts.


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## sportcoupe (Oct 19, 2010)

Looking at heating for hot water and even the van air, I may need to abandon the want for an all electric camper and add propane to the requirements list. Much easier to find efficient solutions for propane hot water and propane air heaters, some even offer a combo unit that does both. That will make the electrical easier to design.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> Looking at heating for hot water and even the van air, I may need to abandon the want for an all electric camper and add propane to the requirements list.


I was wondering how long it would take you to realize that. I would not have an RV without propane to do the cooking, heating, refrigeration, and generator. That is why many come with Propane Tanks. Batteries are for lights and entertainment.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> I was wondering how long it would take you to realize that. I would not have an RV without propane to do the cooking, heating, refrigeration, and generator. That is why many come with Propane Tanks. Batteries are for lights and entertainment.


Yes but we wouldn't have innovation if people just followed what everyone else did. I'm no Nikola though.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Looking at heating for hot water and even the van air, I may need to abandon the want for an all electric camper and add propane to the requirements list. Much easier to find efficient solutions for propane hot water and propane air heaters, some even offer a combo unit that does both. That will make the electrical easier to design.


Absofookinlutely. Just silly to fry eggs bake a cake or boil water with DC electricity.

Unless you're sizing the bank for aircon or propulsion anyway


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## john61ct (Feb 25, 2017)

brian_ said:


> None of the lithium chemistries have nominal voltages high enough get away with three cells in series, and even the lowest-voltage common lithium chemistry (LiFePO4) runs at voltages which are too high to be ideal with four cells in series.
> 
> I know that my motorhome's furnace is not happy with the charging voltage for my lead-acid batteries; at the peak charging voltage for any lithium battery I would want a voltage regulator between the battery and most loads. I do understand that most people using LiFePO4 in RVs likely just run all loads at battery voltage.


I never charge 4S LFP higher than 14V, usually 13.8V.

Under load stays around 13.1-2 cutoff at 12V.

Avoid the shoulders, gain longevity, no need to balance.

Never came across a load wasn't just fine with that, much less V sag than lead for winches, huge inverters etc.


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## brian_ (Feb 7, 2017)

john61ct said:


> I never charge 4S LFP higher than 14V, usually 13.8V.
> 
> Under load stays around 13.1-2 cutoff at 12V.
> 
> ...


Yes, that would be within the range typically used for lead-acid, and so not a problem for an RV.  That does make LFP the only sensible lithium chemistry, unless voltage regulation is used for sensitive loads.

Does that voltage range give the nominal capacity, or some fraction of it?


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## brian_ (Feb 7, 2017)

sportcoupe said:


> Looking at heating for hot water and even the van air, I may need to abandon the want for an all electric camper and add propane to the requirements list. Much easier to find efficient solutions for propane hot water and propane air heaters, some even offer a combo unit that does both.


The other fuel solution is diesel, since both water and space heaters are readily available. It seems fairly common to go with only diesel and solar in expedition campers (perhaps due to fuel availability worldwide). That only makes sense if the van has a diesel engine (which this one presumably doesn't).


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## sportcoupe (Oct 19, 2010)

brian_ said:


> The other fuel solution is diesel, since both water and space heaters are readily available. It seems fairly common to go with only diesel and solar in expedition campers (perhaps due to fuel availability worldwide). That only makes sense if the van has a diesel engine (which this one presumably doesn't).


I'm looking at Promaster due to cargo volume and other pros. You can't get diesel in it anymore. The Transit and of course Sprinter both offer diesels. It is something to consider for sure.


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## john61ct (Feb 25, 2017)

brian_ said:


> Does that voltage range give the nominal capacity, or some fraction of it?


With big prismatics like CALB or Winston, and a good vendor (not trying to save money) actual capacity at vendor voltages (14.6V down to ?10.5?) has been higher than rated.

No significant AH capacity is gained at the top shoulder between 13.8-9 vs 14.6V, maybe 2-3%

And in daily use going below 12V gets dangerous, especially at low current lows. Maybe 10% sacrificed for longevity there.

But the cycles vs avg DoD curve rules, just like lead, so building in a Reserve say 30-40% in your sizing may double or triple lifetime.

Long as you don't murder them of course, a high risk over say ten years.


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## Sunking (Aug 10, 2009)

john61ct said:


> I never charge 4S LFP higher than 14V, usually 13.8V.
> 
> Under load stays around 13.1-2 cutoff at 12V.
> 
> Avoid the shoulders, gain longevity, no need to balance.



I agree with this. For 12 and 24 volt LFP systems a BMS is just a waste of time and money, and will kill your pack. I do not even use one for 32S 96 volt pack in my golf cart. All successful Solar Systems I have designed do not use any BMS.


Just Bottom Balanced the cells, charge to 13.8 volts, and LVD at 12 volts. This really works great on solar systems because you just Float Charge the batteries and never disconnect panels. With a POS BMS, you have to terminate charge and disconnect the Solar Panels which is STUPID because if the batteries are charged by noon, you disconnect the panels and go on batteries while the Sun is still up and usable. All it does is kill the batteries faster. Let them Float and all you use is power from the panels and save your batteries for night and rainy spells. 




john61ct said:


> Never came across a load wasn't just fine with that, much less V sag than lead for winches, huge inverters etc.


This part I do not fully agree with. LFP are drop in replacements for Pb, and no changes are required. However Chi-Com LFP batteries do not have the high C-Rates of a good lead acid, and there is no contest against AGM will run circles around any Chi-Com LFP. A Chi-Com LFP internal resistance is 2 to 3 times higher than than a Pb battery of same AH capacity. You can take say a 55 AH Optima Red Top and put it up against a 100 AH CALB, and the Optima will outperform the LFP with respect to voltage sag by a large margin. To get really low Ri would require you to buy a quality LFP cell from reputable manufactures like A123 Systems or LG Chem, but you will pay up some 400% to get them if they were available.


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## brian_ (Feb 7, 2017)

sportcoupe said:


> I'm looking at Promaster due to cargo volume and other pros. You can't get diesel in it anymore. The Transit and of course Sprinter both offer diesels. It is something to consider for sure.


Most companies building Class B and C motorhomes using the ProMaster went with the gas engine from the beginning, presumably for cost savings. All manufacturers have had challenges getting diesel engines approved and sold in the last few years, but I didn't realize that FCA had given up on diesel for the ProMaster. In the rest of the world this van (the Fiat Ducato) is diesel-only.


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## Sunking (Aug 10, 2009)

brian_ said:


> Most companies building Class B and C motorhomes using the ProMaster went with the gas engine from the beginning, presumably for cost savings. All manufacturers have had challenges getting diesel engines approved



That you can blame on the Employment Prevention Agency. Last thing they want in the USA is efficient diesel engines. Go to about any other country in the world, and passenger car fleets are mostly diesel engines. They get much better gas mileage. If it were not bad enough the enough the EPA make sit almost impossible to pass ever increasing emission standards no manufacture can can keep up with, Those that do pass are forced to pass those cost on to consumers. For those manufactures that do offer diesel engine options in the USA, EPA has an answer for it by making refining requirements so high making diesel significantly higher price than gasoline so no one will buy the cars because the fuel is too expensive. The Employment Prevention Agency needs to go and be replaced. EPA is Nixon's last one finger salute to America, he gave us the EPA before he resigned and laughing at us now. He made it look like a Democrat program.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> Most companies building Class B and C motorhomes using the ProMaster went with the gas engine from the beginning, presumably for cost savings. All manufacturers have had challenges getting diesel engines approved and sold in the last few years, but I didn't realize that FCA had given up on diesel for the ProMaster. In the rest of the world this van (the Fiat Ducato) is diesel-only.


The US version of the promaster diesel had an automatic manual transmission. It was not successful (non-popular) and was problematic. That and the EPA went after FCA diesels in 2016 after it screwed Volkswagen over big time.

Transit has a diesel. I am thinking about it but the ecoboost V6 is a beast in the Transit. It would be hard to pass it up.

Sprinter is bring a gasoline version to the mix in 2019. 

I will drive all three before making final decision.


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## sportcoupe (Oct 19, 2010)

Sunking said:


> That you can blame on the Employment Prevention Agency. Last thing they want in the USA is efficient diesel engines. Go to about any other country in the world, and passenger car fleets are mostly diesel engines. They get much better gas mileage. If it were not bad enough the enough the EPA make sit almost impossible to pass ever increasing emission standards no manufacture can can keep up with, Those that do pass are forced to pass those cost on to consumers. For those manufactures that do offer diesel engine options in the USA, EPA has an answer for it by making refining requirements so high making diesel significantly higher price than gasoline so no one will buy the cars because the fuel is too expensive. The Employment Prevention Agency needs to go and be replaced. EPA is Nixon's last one finger salute to America, he gave us the EPA before he resigned and laughing at us now. He made it look like a Democrat program.


Partially because diesel fuel is much cheaper then petrol (gasoline) in most other countries. Also EPA restrictions installed for US market diesels makes them very complicated engines and expensive to fix. Example is DEF or diesel exhaust fluid and the regen system. Run out of DEF and you cannot just add more and drive, it needs reset by the dealer to even start the engine again in some cases.


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## sportcoupe (Oct 19, 2010)

I've been researching and cannot find reasons to prohibit installing AGM (or even FLA) house batteries under the van as long as they are protected from impact hazards and away from excessive heat.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> Partially because diesel fuel is much cheaper then petrol (gasoline) in most other countries.


Correct and the EPA made damn sure Diesel in the USA would be higher by making refineries refine diesel more than other countries. All done to discourage deisel fuel use by design. That means the EPA does not care about efficiency and want to punish the citizens. 









sportcoupe said:


> Also EPA restrictions installed for US market diesels makes them very complicated engines and expensive to fix. Example is DEF or diesel exhaust fluid and the regen system. Run out of DEF and you cannot just add more and drive, it needs reset by the dealer to even start the engine again in some cases.



Again intentional by design to keep diesels out of the country and punish those that can get in. Want a diesel engine. By a Dodge Ram Truck. No DEF required.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> I've been researching and cannot find reasons to prohibit installing AGM (or even FLA) house batteries under the van as long as they are protected from impact hazards and away from excessive heat.


Sure what do you think the problem would be?

Strong skid plate under!


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## john61ct (Feb 25, 2017)

Sunking said:


> I agree with this. For 12 and 24 volt LFP systems a BMS is just a waste of time and money, and will kill your pack.


Well I see "BMS" not as a thing, but clusters of protective functionality.

The active cell balancing is not needed, and therefore its complexity violates KISS, Occam's Razor.

To be discussed further another time.

> Bottom Balanced the cells
By avoiding the shoulders doesn't really matter. In House use I don't go below 2.99Vpc, redundant protection there, and that is farther from the low shoulder than 3.45Vpc is from the top one, so I top balance

I don't like to Float, so if convenient once LFP is full I continue the charge source for carrying loads, just isolate the LFP and let the lead buffer and support loads if needed.

If that is too complex for the context, I drop float to 13.2, enough to keep SoC in place but nit stressful. If not actively cycling I keep SoC low, and 13.2 Float is also good for that.

> LFP are drop in replacements for Pb, and no changes are required. 

On the load side maybe but not true for charging, if longevity is desired I ensure sources are user custom adjustable.

>However Chi-Com LFP batteries do not have the high C-Rates of a good lead acid, and there is no contest against AGM will run circles around any Chi-Com LFP. 

No idea what that means.

Large prismatics from Winston/Thundersky/Voltronix, CALB, GBS, A123 & Sinopoly have no issues with multiple C-rate if needed.

I do not buy cheap LFP, here $700 USD is cheap per 100AH 4S, can be $900+ with shipping.

House rarely requires over .5C in my experience. In that neighborhood, and certainly higher rates, as SoC drops, voltage drops less with LFP than with lead at the same AH size.

Optima are no longer relevant to deep cycling use since Enersys sold them to JCI. Glorified Starter bat, good for winches etc as you say, but very poor cycle longevity.

Here AGM is very poor value, only install when the space requires sideways or access to add water is inconvenient.


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## Sunking (Aug 10, 2009)

john61ct said:


> > Bottom Balanced the cells
> By avoiding the shoulders doesn't really matter. In House use I don't go below 2.99Vpc, redundant protection there, and that is farther from the low shoulder than 3.45Vpc is from the top one, so I top balance



You have to pick one or the other, Top or Bottom. With Bottom Balance you Balance at 2.4 to 2.5 volts. 



When Bottom Balance you set two known reference points.


Capacity = 0 AH @ 2.5 vpc. Makes it impossible to over discharge any cell. They all arrive at 2.5 volts at the same time with 0 energy in the cells so they cannot drive adjacent cells to reverse polarity and destroy themselves. 



With Top Balance you only know each cell is at 100% SOC, capacity is unknown. As you discharge the weakest cell can easily fall below 2.0 volts while the others are at 3 volts or higher, and wil destroy the discharged cells. In other words you set yourself up to destroy the batteries by making it possible. 



The real danger is 2.0 vpc. 2.5 is manufactures covering their butts. On a 4S system you would set LVD anywhere from 11 to 12 volts, well above 8 volts on a fully discharged 4S pack. To charge is simple. Set it to 13.8 volts and let them float until the cows come home. SOC will be in the 90's just before you reach the shoulder. 



LFP are the most high voltage tolerant of all lithium batteries. They can be charged to 4.2 volts without much damage or risk of fire. But like any lithium battery will not tolerate over discharged, so stay clear of the bottom shoulder. You can flirt with the top shoulder if you do not mind sacrificing some cycle life to get that last 1 to 4% SOC, bu tthat means you are stuck inside a lead acid battery box using a lead acid BIBLE verse 1:


1. Thou Shall Charge To 100% or thy will be cast to hell in a crypt of hardened Lead Sulfate Crystals.


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## john61ct (Feb 25, 2017)

Again, in normal cycling I **never** go below 12V / 2.99Vpc, nor above 14V / 3.5Vpc.

With quality cells, even if capacity not perfectly matched, staying in that range and gentle House currents, things just don't get unbalanced, not for years and years.

Many banks over 8 years old, 2000+ cycles, most zero loss of capacity, many still above rated. Starting to think calendar aging will end up mattering more than #cycles.

A far cry from EV usage of course, and I don't think you'd get that going up to 14.5V or whatever the stupid vendor specs are.

Key is (besides protecting from catastrophe of course) keeping SoC low until your loads need to be fed, never just sit at high SoC. Need to unlearn lead thinking.


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## sportcoupe (Oct 19, 2010)

Lots and lots of back and forth discussions here. That's a good thing. Makes me stop and think. 

It may seem weird to design electrical before even having van but that will drive camper van layout and design. Electrical is almost the first thing to install in a camper conversion. I can't let furnishing layout dictate the electrical system very much. 

Now I've added a propane tank to the mix. Yay! 

I hate low hanging underslung "stuff" on a traditional RV, otherwise I'd be tempted to buy and not build. Ground clearance is very important to me as I venture off pavement often.

Here's just one picture from last months 8000 mile trip. It took me 2.5 hours to go 16 miles to this spot (Point Sublime, AZ).

Now, what will meet my needs the best? FLA is best value and will take-up valuable space inside van unless I cut a hole in floor and make a box. AGM I can completely mount under van sideways. AGM also have lower Ri with it's benefits.


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## Sunking (Aug 10, 2009)

john61ct said:


> Again, in normal cycling I **never** go below 12V / 2.99Vpc, nor above 14V / 3.5Vpc.


That is fine, but you still have to pick a Balance Point. You cannot just take cells from the distributor, hook them up in series. The SOC of the cells are all over the place. You have to equalize them at some SOC initially to start. If you are not using a BMS Botom Balance is default choice, Top Balanced is the last thing you want with no BMS. 

At a minimum connect them all in parallel and walk away for a day to get them Mid Balanced to the same equal SOC voltage. From there it is easy to Top or Bottom Balance. Either discharge to 2.5 volts, or charge them to 3.6 volts. 

If you are not going to run a BMS, you had better Bottom Balance, or you still risk over discharge. If you were to Top Balance and not run a BMS, you have set yourself up to over discharge at least one cell, the lowest capacity cell in the string.


Balanced is a poor term. Equalized is a much better term and makes more sense and easier to understand. Example Bottom Balanced we have equal voltage and capacity, a known reference point of 0 AH capacity @ 2.5 Volts @ 0% SOC. Hook the cells in series, and every cell has the exact same capacity. Top Balanced and all you have Equalized and know is 100% SOC @ 3.6 volts. Capacity is unknown and determined by the weakest cell. You can easily over discharge a cell in systems greater than 4S. Example 49 volts is good if you assume 3 vpc on a 16S pack with LVD set to 48 volts. If you had only known 1 of those 100 AH cells you bought is only 80 AH. That poor little weak cell is siting at 2 volts and all his mates are at 2.9 to 3.1 volts or greater fooling you into thinking everything is OK. That is what happens when you Top Balance. If you Bottom Balance that cannot happen. The cell voltages equalize as they discharge. and all arrive at 2.5 volts at the same time well below your LVD set point of 48 volts.


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## john61ct (Feb 25, 2017)

Sunking said:


> That is fine, but you still have to pick a Balance Point.


I clearly stated I top balance.

My point is bottom or top makes little difference given the conditions I cited.

None of the cells ever get near either of the shoulders.

> If you are not going to run a BMS, you had better Bottom Balance, or you still risk over discharge. 

No, as I stated I have redundant LVDs, all close to 3.00Vpc.

No cell has ever hit 2.9V

If the conditions I outline are followed none of these issues are significant.

I have lots of BMS **functionality**, for example isolation from the charge bus well above freezing ambient.

Loads buss isolated at much colder.

Most BMS do not do that, for me it is critical.


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## Sunking (Aug 10, 2009)

john61ct said:


> I clearly stated I top balance.



My bad, I missed it. 




john61ct said:


> My point is bottom or top makes little difference given the conditions I cited.



That only works for 4S and 8S. Go to 16S or greater as explained in my last reply and now you are a setting duck for accidental over discharge. 48 volt LVD will not work because you can be as high as 50 volts with a dead cell on a Top Balanced pack. You eliminate the risk bottom balanced and still meets your objectives. It exceeds your objective and cost nothing. Just a change in logic.


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## GreenGyver (May 4, 2015)

If Lipos are only used in RC vehicles, why are they found in commercial electric vehicles? If only 100 cycles, then EV's would stop working before the end of a year. Yes, Lithium Ion batteries are the most unstable, Lithium polymer being more stable, and LiFe batteries being the most stable.

Oh and C-rates for RC type batteries are typically much higher than 20C....just look it up to see how much hot air Sunking is blowing. Gotta love when people think they know everything because they did one install and are suddenly experts.

When considering the type of battery you want, make sure to look at how much charge they can take at a time. That will help determine what application you would like to use them for.




Sunking said:


> They cannot and is of no concern for scum bag spammer. LiPo is the last thing you want for a house battery or any application requiring long life as LiPo only have roughly 100 cycles in them. LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.
> 
> 
> 
> They do have a application in EV used as Drag Racers where you can put a very small battery in, just enough for 1 or 2 runs. Some of the new ones claim 100C-Rate for 10 seconds which is all you need for a drag race. A 20 pound battery vs a 1000 pound battery.


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## brian_ (Feb 7, 2017)

GreenGyver said:


> If Lipos are only used in RC vehicles, why are they found in commercial electric vehicles?


Just to be clear, "LiPo" means lithium-polymer, or battery of cells with lithium-ion technology and using a polymer electrolyte instead of a liquid electrolyte.

My understanding is that most EV battery cells do not use polymer electrolyte, but the Hyundai Soul EV does, according to Hyundai. According to one report the Hyundai battery is from SK Innovations, and is NMC chemistry.

I think that most people in these discussions assume that "LiPo" or "Li-poly" or "lithium polymer" means something specific about the chemistry, not just the use a (gelled) polymer electrolyte. Invalid assumptions cause misunderstandings. To avoid misunderstandings, what are the EIG cells which you are selling, GreenGyver? Are they the T020 pouch cells? If so, they are LTO cells; it looks like most small cells (including those used in the RC world) described as "LiPo" are probably LCO chemistry.



GreenGyver said:


> Yes, Lithium Ion batteries are the most unstable, Lithium polymer being more stable, and LiFe batteries being the most stable.


That makes no sense; lithium polymer cells _are_ lithium-ion cells, and all of these are lithium-ion cell types:

lithium cobalt oxide (LiCoO2, a.k.a. *LCO*)
lithium iron phosphate (LiFePO4, a.k.a. *LFP*)
lithium ion manganese oxide battery (LiMn2O4, Li2MnO3, a.k.a *LMO*)
lithium nickel manganese cobalt oxide (LiNiMnCoO2, a.k.a *NMC*)
lithium nickel cobalt aluminum oxide (LiNiCoAlO2, a.k.a. *NCA*)
lithium titanate (Li4Ti5O12, a.k.a. *LTO*)
So "LiFe" batteries cannot be more stable than lithium-ion batteries, because "LiFe" (actually LiFePO4 or "LFP") _*are*_ lithium-ion batteries.




GreenGyver said:


> Gotta love when people think they know everything because they did one install and are suddenly experts.


It seems highly unadvisable to judge anyone else's expertise based on your incomplete knowledge of their background. The number of installations is a poor measure of either knowledge or understanding, anyway.


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## sportcoupe (Oct 19, 2010)

What will meet my needs the best? (FLA, AGM or....) and (200Ah, 400Ah, 600Ah or....)


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## Sunking (Aug 10, 2009)

GreenGyver said:


> If Lipos are only used in RC vehicles, why are they found in commercial electric vehicles? .


They are not found in EV's you moron spammer. Now get lost.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> What will meet my needs the best? (FLA, AGM or....) and (200Ah, 400Ah, 600Ah or....)


The point is you gather the info / knowledge to make your own decision based on the facts.

My default is FLA.

Size depends on AH used per 24hrs, and recharge sources available.


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## Sunking (Aug 10, 2009)

brian_ said:


> Just to be clear, "LiPo" means lithium-polymer, or battery of cells with lithium-ion technology and using a polymer electrolyte instead of a liquid electrolyte.



Today LiPo does not have a meaning, it is a Marketing Buzz word. You are correct in the sense in that they use a plastic or polymer electrolyte, to my knowledge no manufacture makes then because there is no application suited for them. Their Internal Resistance is so high make their Specific Power Density to low to be usable for most practical application except for maybe a clock. 



In the RC World they do use the name LiPo which is really BS. Hard to nail down exactly what chemistry they use, but most from what I can tel are pouch LCO cells on steroids with a liquid electrolyte. A new new so called HV Graphene LiPo claim as much as 100C rate which again is meaningless, but me thinks those might be NMC variant because cell voltage is roughly 3.8 volts.


But all sources and the manufactures of all LiPo cells only claim 100 to 200 cycles. Personally with over 200 LiPo cells in my posession, I have never seen a LiPo make it past 100 cycles before they puff up like a balloon and can no longer deliverr high current rates and are more of a Space Heater than battery as they get extremely hot trying to use them as intended. 



As far as EV manufactures and EV batteries? Well what I do know if tou go to say Panasonic, and look at say the same cell they made for Telsa Roadster, the spec sheet only claims 500 cycles. Go to LG Chem and you are not going to find many cells that even go 500 cycles, but offer no warranty. 



Does make one wonder how EV manufactures can offer such long warranties on their batteries when it is not possible on paper. I know one thing, commercial EV manufactures do what I do because that is where I learned to extend Lithium battery cycle life only charge up to 90%, and cut-0ff at 10 to 20% which should get you up to around 1000 cycles, and that translates to 5 to 7 years. 



LTO cells you talk about will never likely be used in a EV, they pack a punch with respect to Specific Power as they do have the highest Specific Power Density of all the Lithium batteries which is what you want in an EV. However they have very low Specific Energy equal to lead acid. LTO if they can get the price down, which I never see happening, would be excellent for Renewable Energy Storage because they have the potential to be a very long lived battery.


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## Sunking (Aug 10, 2009)

sportcoupe said:


> What will meet my needs the best? (FLA, AGM or....) and (200Ah, 400Ah, 600Ah or....)


Figure it out yourself. Sorry but that is your job. 

If it were me, FLA all the way because they last a lot longer and from cradle to grave cost 1/4 that of AGM. Price out both AGM and FLA at a given voltage and capacity. AGM cost roughly twice as much per Kwh of capacity, and last roughly half as long as FLA. So when replacement time comes you end up paying 400% more in the end.

This is why I said you need to justify the added expense. AGM has it place, a very special niche application place. Like where extremely high charge/discharge rates, extreme cold environments of -40 degrees and lower, unusual installation orientation, extreme mobile applications like aircraft or off-road vehicles, or where spills cannot be tolerated and would threaten life safety. 

My advice is sit down and have a good heart to heart conversation with your wallet. In the end, it is your job to figure out and decide.


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## john61ct (Feb 25, 2017)

US market, best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club. 

Deka-labeled same batts also sold at Lowes.


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## john61ct (Feb 25, 2017)

Note some go AGM for spec'd high CAR thinking will reduce run-time charging from ICE.

In fact, as with all lead, the higher CAR only applies for the first hour or two, to get to 100% Full (per endAmps, required "most cycles" for longevity) still takes 6-7 hours total.

But yes for discharge, lower resistance means lower total capacity required for short high-current loads like microwaving popcorn, and less V sag than FLA.

Odyssey PC-2150 is an excellent example for that, true Dual Use, great for winching etc but also very good deep-cycling usage longevity (for AGM) if well coddled otherwise.

But as SK points out **much** more expensive "per AH per year" than even the priciest FLA.


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## sportcoupe (Oct 19, 2010)

What is CAR?


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## john61ct (Feb 25, 2017)

Charge acceptance rate.

Lifeline AGM can take .85C for example. 

However that will last only a few minutes as SoC rises Amps accepted falls drastically.

More real life, with the same high-CAR AGM bank, the difference between a .4C available source and a .2C one may be only 40min over 6+ hours.

Now quality FLA might accept say .25C , but that tapers as least as quickly, so might add another 40min to the slower example above.

My point is spending so much more "per AH per year" for the purpose of faster charging, is IMO hardly worth it.


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## john61ct (Feb 25, 2017)

However all that goes away with LFP.

Charge as fast as you like, they accept it all the way up the SoC curve.

In theory even 3-4 days' usage can be refilled in an hour with a big enough ICE source.

But I keep to .2-.3C charge rates for longevity's sake.

Even lower is better if convenient, enough solar would be ideal given a big enough roof.


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## Sunking (Aug 10, 2009)

sportcoupe since you are in planning stages is a good thing, many fail to plan or think things out and you get what you deserve. Allow me to point a few things out, and what I have learned in my career. 

First thing will strike you as odd, but for now forget AMP HOURS. Jest get that out of the equation and consideration. All it will do is cause errors. Amp Hours is a end result after all the calculations have been done. It is the LAST CALCULATION. In fact it is not a calculation, just a simple Conversion.. You are not consuming Amp Hours, you are consuming Watt Hours which is the real work, energy used, and what you use to calculate everything.

So the very first step in the process is sit down, be careful what you ask for, and determine how many watt hours you need in a 24-hour day. It is pretty easy to do. If you are not sure, ask. In a nutshell find how many Watts each gadget and gizmo uses, and then multiply by the number of hours you expect to run it in a 24 hour period. Example say 50 watts x 3 hours = 150 watt hours. Add them all up and say you get 1500 Watt Hours per day. 

OK Solar and RV's I am afraid to say are very challenging. They do not play well together. There are many obstacles to overcome. To determine panel wattage all data sources assume ideal conditions, and in an RV you cannot even get close. Example we are looking for Sun Hours. Depending on where you are at and time of year can vary. In general 5 Sun Hours in Summer, and 2 to 3 in Winter. That assumes absolutely no Shade Issues from sunrise to sunset, at optimum tilt/orientation angle, at moderate cool temps. That would mean parking in Full Sun with no shade in eye site. Park at the perfect angle to orient panels solar south. Then have a way to elevate the panels off the roof so they can stay reasonable cool, and provide the proper tilt angle. See any problems doing that, and be confident you got it right? Good luck with that. 

But lets say you did get it right. What panel Wattage is required? That is where we need Sun Hours and Daily 24-Hour Watt Hour Usage. If you want to pay more money than necessary, use an inexpensive PWM Charge Controller. If you use a PWM Controller *Panel Wattage = [Daily Watt Hours x 2] / Sun Hours. *Example 4 Sun Hours and 1500 wh. 1500 x 2 / 4 = 750 watts minimum. Did you ask yourself why PWM is more expensive? 

Now if you want to save money, make things efficient, less material less space required, use a quality MPPT Controller. They will cost you 5 times more than PWM. OK with a *MPPT Controller Panel Wattage = [Daily WH x 1.5] / Sun Hours*. So 1500 wh x 1.5 / 4 = 562 watts. 550 watt sis close enough.

As for Controller is easy. Run through the MPPT panel wattage 550 watts. Minimum *MPPT Controller Amperage = Panel Wattage / Nominal Battery Voltage +1 volt per 12 volt of battery*. You already know 12 volt battery + 1 volt = 13 volts. So 550 watts / 13 = 42 amps so you are looking at a 40 to 45 amp controller minimum for either PWM or MPPT. They both wil delive the same current, PWM just needs a lot more wattage than MPPT. 

However that is not the only place you save a ton of cash with MPPT. If you use PWM you must, and I say MUST use very expensive low voltage 12 volt battery panels. You must also wire all the panels in Parallel. Two last things you never want to do. Low Voltage battery panels wil cost 2 to 5 time $/watt of Higher Voltage Grid Tied Panels. Being lower voltage means smaller wattage panels. 180 watts is about as big as 12 volt battery panels come in. At 750 watts means 5 x 150 watt panels wired in parallel. Once you have more than 2 parallel Strings is going to require expensive Combiner, and Fuse/Breaker assemble. After Combined you will be running 45 amps to the Controller Input which requires some heavy 6 AWG cable to figure out how to run in. Also mean racking hardware x 5. Not what you want to do and the biggest error almost all DIY's make. We call it Stuck Inside A 12 Volt Toy Box mentality. Don't do that.

Smart Money is to use much less expensive Grid Tied Panels and MPPT Controller. GT panels run at much higher voltage which means much lower current and more panel wattage up to 300 watts per panel. All you need is two or three panels all wired in series. Example use 2 x 275 watt panels = 550 watts. With the panels wired in series panel current to the Controller Input will be around 9 amps which means a single 14 AWG wire, no fuses or combiners to deal with as they serve no purpose. I use a 20-amp cartridge type at the controller Input for a Disconnect Device. Otherwise if required like PWM to be located at the source; the panels. 

OK all the work is done, what size battery? Well again we need Daily Watt Hours, nominal Battery Voltage and most important number of all is HOW MANY DAY RESERVE CAPACITY. In a stationary system would be a 5-Day Minimum reserve. In real application gives you 3 to 3.5 cloudy day coverage before you run your generator. Determined over years 5 day sis the sweet spot economically getting the most bang from your buck making the batteries last as long as they can yielding maximum energy storage. 

But you are not going to do that. Not required for an RV. You do not use them every day 7 x 24 x 365. RV minimum is 3 days with or without solar. That will give you two full days of run time before you need to do something. Rest is easy and as promised Amp Hours is just the end result with no mistake and taking Peukert, Charge Efficiency, wire losses , and all losses have been accounted for. So now we know daily wh, battery voltage, and reserve time. *Battery AH = Daily wh x Reserve Days / Nominal Battery Voltage*. So we have 1500 wh x 3 / 12 volts = 375 AH

However forget all that work. We used optimum conditions you have no way in heck to do. By the time you de-rated everything from ideal would require well over 1500 watts of panels. Two real expensive charge 60-amp controllers at 12 volts. A lot more current than FLA can take, but AGM could if money is no object.

Make it easy in an RV determine daily wh, 3--day reserve capacity. Find Capacity which is the same 375 AH battery. Accept the fact Solar is not going to be your primary power source and treat it as Supplemental Power. Use an Electronic Battery Isolator to allow engine alternator to do charging. If driving daily or every other day will be your primary power source assuming you are driving a few hours. If you add solar can add a day to that. Carry a generator and charger. Size Genny to run the loads and charge battery at max rate.

Want solar with that? Easy peazy money bags. Size panel wattage and controller to supply roughly C/10 charge current or as much as you can afford without going over C/8. No need to waste money on something that is not your primary source *Panel Wattage = C/10 Current x Nominal Battery Voltage + 2-volt per 12 volt battery*. 38 amps x 14 volts = 532 watts. 2 x 250 watt panels and 40 amp MPPT Controller. Even with Solar still requires a generator and/or driving if you spent that $75 on an Electronic Battery Isolator.


Last comment on the RV battery type. 3 days FLA, AGM, LFP, or ABC--123 makes no difference. All will work with above. 



So go figure it out.


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## john61ct (Feb 25, 2017)

Another approach.

If you use lead, and live long periods off grid, you must have solar.

If your roof is less than 30' long, then fill it up with panels.

Maximum watts per sq ft area, jigsaw approach different sizes if necessary, and ideally using panels rated over 40Voc.

Then match up like panels and buy Victron SmartSolar SCs rated to handle the wattage (amps), e.g. 75/15 handles 200-250W worth.

______
Now, bank sizing, you say 400AH LFP is enough, if lead that's 600-700AH or so, prolly fine for everything but the aircon.

Best to go over a bit rather than under, or if you might need more, do it before the original bank's too worn.

If you find the solar input is not enough to get you to 100% Full (per endAmps) at least a few days per week, then get an ACR / VSR hooked up to tap into your alternator while driving, and do that high-amp charging in the early AM, keep usage down, give the solar a chance.

Still not enough? Get an inverter genny and a well-matched mains charger. Same early-Bulk routine as above.

Of course, regular access to shore power trumps all other sources.

Done.


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## sportcoupe (Oct 19, 2010)

CAR - good info there. I figured it was tied to Ri.

Low Ri is preferred. I don't want my inverter shutting down under full load after only an hour on a full charge battery pack due to voltage sag tripping inverter min voltage.

Battery type must survive washboard dirt roads for hours and off camber situations at times. This is no street-only RV. 

Primary charge will be electronic relay. Mains charger to give good charge as needed. Van will be driven daily for work and off grid on vacation trips.


I took a stab at daily AmpHrs

12 V DC Appliances and Watts/Amps/Ahr
Furnace fan 48	4.0	16
Light, LED 8	0.8	4
Propane alarm 3	0.2	5
Refrigerator 36	3.0	36
TV 36	3.0	12
Water pump 48	4.0	8


120 V AC Appliances and Watts/Amps/Ahr
Aircon 410	3.4	14
Coffee Maker 800	6.7	7
Cellular phone charger	40	0.4	2
Computer, Laptop	150	1.3	4
Microwave 1000	8.3	8

Watts/Amps/AmpHrs
DC Loads: 193.58	15.0	82.3 
AC Loads: 2410	20.2	34.9


Days usage per week:3.0 
AmpHrs per day:117.2
AmpHrs per week:351.7


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## john61ct (Feb 25, 2017)

A screenshot of the spreadsheet would show up better.

A 12V-12V converter / stabilizer will eliminate voltage drop, but with a big full bank likely not a problem.

Make coffee over propane.


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## sportcoupe (Oct 19, 2010)

Screenshot of a quick spreadsheet


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## john61ct (Feb 25, 2017)

3 pairs of those Deka GCs should do it.

But the battery bank is the least challenging, and certainly the least expensive aspect here.

Getting properly recharged each cycle should be the real focus.

Make sure you have a good SoC meter, and ammeter + AH counter.

If you really do run those IMO crazy inverter loads, count on a big genset running 3-4 hours a day every day, and with lead you will still need as much solar watts as will fit up top

Going to LFP would maybe shorten runtime a bit, and let you forego the solar.


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## sportcoupe (Oct 19, 2010)

The inverter loads are not all at same time or 24 hours a day. They are intermittent loads.


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## john61ct (Feb 25, 2017)

I did not notice anyone stating otherwise?

AH per cycle is the concern, not amps.

For example, 30min per day for the microwave?

Aircon's already been discussed.

Since you need to run the genny for hours anyway, just run the aircon and do your waving while the genny's going, ideally doing some charging then too.

If they're really needed in the first place.


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## sportcoupe (Oct 19, 2010)

What good is the house battery if you never want to use it running genny all the time? 

I can substitute running genny for days that I'm driving 5-6 hours.

I may have over estimated micowave use slightly. 

Aircon is required. I can't sleep when it's hot and humid.

It's much easier to plan the entire electrical and systems before build conversion starts then to wait and redesign for something that just doesn't work during or after conversion. Camper van on paper is easy to change. 

Budget for conversion is $15,000.


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## john61ct (Feb 25, 2017)

OK, so:

With lead, getting properly recharged each cycle will be the real challenge. You will still need as much solar watts as will fit up top.

Going to LFP would maybe shorten ICE charging time a bit, and let you forego the solar completely.

In either case, make sure you have a good SoC meter, and ammeter + AH counter.


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## sportcoupe (Oct 19, 2010)

With lead, you're referring to the absorption portion of the charge cycle correct? Does that apply equally to AGM as FLA?


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## Sunking (Aug 10, 2009)

sportcoupe said:


> With lead, you're referring to the absorption portion of the charge cycle correct? Does that apply equally to AGM as FLA?


All batteries even lithium go through what you are calling is Absorption phase all that means is the Constant Voltage Stage where current tapers to zero. A better term and more accurate is SATURATE. Think of a dry sponge. Dunk it in the water, and even though submerged takes a while to fully saturate slowly. 

Both lead acid and lithium have charge speed limits and they work the exact same way. The faster you charge, the longer you will spend in Absorb mode. When a battery manufacture recommends a specific charge rate, they are telling you the fastest most efficient rate. It is the point of Diminishing Returns. When you charge at say C/10 most manufactures of lead acid batteries recommend, you will arrive at Absorption at roughly 90% SOC, and should take another 2 hours to fully saturate. Charge at say C/4 and you arrive at Absord voltage at 70% SOC and now spend the next 5 hours until you saturate down to 2% of C. So take note you can charge at higher or lower rates. Once you get up to around C/8 on FLA, you hit the brick wall where you cannot charge any faster in time, it wil take 10 hours at C/8 or 1C. Tip here, you can speed up FLA charging time by eliminating Adsorb phase, or at least most of it. Real easy to do, we change the Voltage setting to higher voltage. Say from 14.8 volts for a Trojan FLA product up to 15.0 volts. That forces the MPPT Controller to stay in Constant Current longer. Do not attempt with AGM or any Lithium. FLA no problem. 

Same for Lithium, but the penalty i snot quite so bad. Example most manufactures recommend C/2. Like Pb you hit Absorb voltage at 9o-% SOC and fully saturate within an hour. 

Big difference is with PB you need the ability to be able to fully recharge without time constraints solar puts on you. But do not knock yourself out and get in the mindset they have to be fully recharged every day. A good full charge once a week keeps the doctor away. 

As for meters and such IMHO are a waste of money and not capable of telling you anything. Last thing they will tell you is the SOC. Coulomb Counting Pb is a guessometer and would require calibration every cycle. You have to guess at what the charge efficiency which changes with temps and humidity. Lastly there is no algorithm to account for Peukert effect. They can be useful with FLA, but just a hole in your wallet on Pb batteries. 

As for SOC, common sense will tell you it is useless on a in service Pb battery where it is either discharging or charging. SOC is only useful on an Open Circuit Battery that has rested for 24 hours and comes to 75 degrees F. That is not how the world turns. The real world of an operating system is it is either charging, discharging, or sometimes Floating. 

Check the ole memory vault inside that piece of meat stuck between your ears. Remember being concerned about voltage sag? A SOC meter would tell you the battery is at 0 SOC when you know it is fully charged. I can take a fully charge battery brand new battery and make it read 10.5 volts or even 7.2 volts (CCA voltage) despite being fully charged and in brand new health. 

I can take the same new battery, discharge it down to 0% SOC @ 10.5 volts, and make it read 14.4 volts in under a minute indicating full charge when in fact it is FLAT. 

Not saying a Volt Meter is not useful, but is no indication of the battery SOC. There is only one way to accurately determine a Pb battery SOC and that is with a temperature corrected battery hydrometer. AGM and you are SOL. 

What a meter will tell you is if your system is working. When th esun comes up the voltage should climb to say 14.8 volts, hold 14.8 for a couple of hours, then drop to 13.5 until dark and the voltage will bleed off to 12.6 volts and lower by morning. 

Again I caution you to use watt hours.


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## sportcoupe (Oct 19, 2010)

Updated spreadsheet for watts and reduced popcorn wave times 

Seems like 500Ah FLA and 500W solar would satisfy my power requirements?


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## Sunking (Aug 10, 2009)

sportcoupe said:


> Seems like 500Ah FLA and 500W solar would satisfy my power requirements?


Battery is a little light because that is only a 2-day reserve meaning you will use 50% daily. You could make it work, but not with solar. You are asking for a huge amount of power at 2.8 Kwh daily. 


To generate 2.8 Kwh of usable power with solar with 500 watts of solar panels is impossible even under ideal conditions. With a 500 watt panel under ideal conditions would require a 8 Sun Hour Day. There is no place on earth that has that kind of Solar Insulation any day of the year. 5 to 6 Sun Hours is as good as it gets in summer in Tuscon AZ, and if in Gloomy Doomy Seattle and Portland 4 hours is top on June 21, and by Xmas is less than 1 Sun Hour.

Point here is if you want solar, OK, but it will only be a supplement and show-n-tell material. With a battery only sized with 2 day capacity means you will have to charge with something else because solar is not going to work with you power requirements. No need spending a a lot of money on solar, because no matter how much money you throw at it will not work. A 10 watt panel would be as useful as a 500 watt panel because you will be using either a generator, driving, or shore power to recharge. 



The AC is killing you.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> With lead, you're referring to the absorption portion of the charge cycle correct? Does that apply equally to AGM as FLA?


Well it isn't so much Absorb vs Bulk but total charge time to get to 100% as per endAmps, how it's divided depends on current level.

And yes all deep cycle lead will take 5-7 hours to get there even at high current available, high CAR AGM as I said might save 30-60 minutes over FLA.

And LFP does never **require** any Absorb hold time, since it has no need to ever get to Full, and in fact when not actively cycling, lower SoC helps longevity.

I do use a little AHT, 3.45Vpc / 13.8 until current tapers to .04C, but **only** when precise calibration of 100% Full is required for SoC meters.

This is actually within 2% SoC of the vendor definitions of Full at destructively higher levels.

In normal cycling, I charge **to** that voltage and just stop, no Absorb at all, sacrificing at most another 1-2% capacity, but gaining a lot of longevity, and eliminating any balancing issues.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> 500W solar would satisfy my power requirements?


On days with great insolation conditions - summer or near the equator - you will put maybe 140-180AH into your bank.

Have you checked to see how much will fit on your roof?

Note if your bank is lead, even if your solar is under 20% of your daily AH input, you still need it for the long tail, to have any chance of decent bank longevity off grid.

Running a big genny for hours and hours of very low acceptance make zero sense.


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## john61ct (Feb 25, 2017)

As stated, no Absorb is required for LFP except to calibrate the AH-counting SoC meter. Once every 5-10 cycles is plenty for decent accuracy. I like Victron BMV-712. Peukert coefficient for LFP is so close to 1.0 can largely be ignored.

Yes, voltage is largely useless for estimating SoC.

Absorb for LFP should be very short, at low rates a matter of minutes - stop at .04C or hurting longevity, pushing into the shoulder.

LFP can accept very high C rate charging, no less efficient but temps need watching - .5C is a reasonable limit for longevity.

Quality AGM makers recommend over .2C for longevity, Lifeline's minimum is .4C.

Hitting 100% SoC once a week is still PSOC abuse and will drastically shorten lifespan. Every cycle is ideal, most cycles is good, a few times a week is OK.


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## sportcoupe (Oct 19, 2010)

Roof length is between 12–14 feet in length, almost 80” wide. Just one fan is planned so the rest could be solar. 

Saying 500w solar panels are the same as a 10w panel because neither will supply 100% of plannned demand is kind of silly. Sure it’s supplemental but 500w seems substantial to me. Might even work most days because the van will be moving hence charging. I’d almost never leave it parked for two days and not drive it.


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## GreenGyver (May 4, 2015)

Sunking said:


> They are not found in EV's you moron spammer. Now get lost.


Sunking, you need to chill-out and learn some manners. How old are you, 15? Yes they are found in EV's, they are also used for backups or high energy storage.

LiPos are not Lithium Ion. That's like saying NiCD are the same as NiMH batteries. Their are pros and cons to all different types of battery chemistry. Some have higher internal resistances than others. However, if you have a large enough bank, then it doesn't matter as you would be able to pull in all solar energy as it would be distributed over your entire bank. Kind of like pouring water into an ice cube tray really fast.

Stop spamming me Sunking and offer information, not animosity.


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## GreenGyver (May 4, 2015)

Sunking said:


> They cannot and is of no concern for scum bag spammer. LiPo is the last thing you want for a house battery or any application requiring long life as LiPo only have roughly 100 cycles in them. LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.
> 
> 
> 
> They do have a application in EV used as Drag Racers where you can put a very small battery in, just enough for 1 or 2 runs. Some of the new ones claim 100C-Rate for 10 seconds which is all you need for a drag race. A 20 pound battery vs a 1000 pound battery.


(1) Lithium batteries have been used heavily in all EV's, not just drag racers.
And please by all means Sunking, tell me what deep-cycle or AGM battery can put out the equivalent of a Lithium pack and weigh less? However, I don't think weight is much of a concern in the case posted here anyway. So I'm not sure why you are making a case for it. And while Lithium Ion batteries are more unstable, I don't have Lithium Ion, they are Lithium Polymer, which are used heavily on electric bike conversions as well. Don't hear about a lot of fires with them....or are you just talking smack?

(2) You get different voltages from configurations that are higher, such as a 4S configuration that would have a nominal voltage of 14.6V using things like DC converters and voltage regulators.

I've built battery banks using these before. Mostly for my personal computer, but have also used it in conjunction with a couple solar panels on top of my camper, and other projects. The only real limitation I'd say they have would be their terminal voltage being around 3-3.2V and requires a monitoring device and charger that can prevent over-discharge and over-charging.


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## GreenGyver (May 4, 2015)

Brian

I couldn't find the the actual post you made within the length of this thread. Here's a link to all the information I have gathered on these cells. 

https://drive.google.com/file/d/1Wlxp7owKb3vn9fsp4GlT_JU9S07ufezu/view?usp=sharing


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## brian_ (Feb 7, 2017)

GreenGyver said:


> Brian
> 
> I couldn't find the the actual post you made within the length of this thread. Here's a link to all the information I have gathered on these cells.
> 
> https://drive.google.com/file/d/1Wlxp7owKb3vn9fsp4GlT_JU9S07ufezu/view?usp=sharing


In the Classified thread (to which you're probably responding), I linked directly to my post... 


brian_ said:


> ... To avoid misunderstandings, what are the EIG cells which you are selling, GreenGyver? Are they the T020 pouch cells? If so, they are LTO cells...


But anyway, thanks for the information. There's not much specifically about the cells in the module specification document, but by comparison of voltage specifications, these are not the T020 cells - the nominal voltage is too high for that.

Nothing in that module document indicates either the chemistry (although not LTO or LFP) or the construction (polymer electrolyte?) of these EIG cells.


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## brian_ (Feb 7, 2017)

GreenGyver said:


> LiPos are not Lithium Ion.


Saying that LiPo is not lithium-ion is like saying that sedans are not cars; yes, a sedan is a specific style of car, but it's still a car.



GreenGyver said:


> Their are pros and cons to all different types of battery chemistry..


True, but "LiPo" does not describe the battery chemistry, just one aspect of the cell design. What chemistry are the cells that you are selling, and what chemistry do you think that common RC cells use?


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## brian_ (Feb 7, 2017)

Sunking said:


> LiPo's are used in RC aircraft where C-Rates run 20C or greater continuous. Extremely dangerous lithium batteries notorious for catching fire.
> 
> They do have a application in EV used as Drag Racers ...


I'll note that these comments are specifically about LiPo (lithium-ion polymer) cells, not all lithium cell types.



GreenGyver said:


> (1) Lithium batteries have been used heavily in all EV's, not just drag racers...


Of course - every current production EV (and plug-in hybrid) uses some form of lithium battery, and I doubt that anyone is suggesting otherwise. The drag racing comment was about LiPo cells, specifically.


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## brian_ (Feb 7, 2017)

GreenGyver said:


> (2) You get different voltages from configurations that are higher, such as a 4S configuration that would have a nominal voltage of 14.6V...


I think it's safe to assume that everyone is this conversation is well past the extreme novice level at which they need someone to tell them that adding cells in series increases the pack voltage.


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## brian_ (Feb 7, 2017)

GreenGyver said:


> ... However, I don't think weight is much of a concern in the case posted here anyway.


That's for sportcoupe to decide, but I think that weight is a significant concern for such a large battery in a small RV. Weight (and weight distribution) is always a concern in RVs, and we're talking about energy storage capacity at least four times as high as is typical for the base configuration of a small RV (which usually has a single 12V lead-acid battery of 80 to 110 Ah capacity), and double the capacity typically carried by large RVs (two GC2 6V, for about 230 Ah @ 12V).

Weight may be the most common reason given by RV owners for wanting a lithium battery.


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## sportcoupe (Oct 19, 2010)

So I can see the possible benefits of using solar if the house battery is FLA (or AGM). The major one is 100% charge several times a week. I understand I could plug in if readily available too. It isn't likely I'd run a genny to get a proper absorption charge on a large house battery bank.

LFP is another matter. I could invest the money for a larger house battery instead of running solar. I suppose a ~800Ah LFP pack would easily handle my crazy inverter ideas. 

If I go LFP, I'd go Calb now after some study. Trouble is they discontinued the CA400 cells. The largest they make is 180Ah. Using them, there's no way to single string a 12v pack. I'd have to parallel. 

I've had bad experience in paralleling in the past without a BMS. Can a 3P4S or 4P4S LFP pack be made to last without breaking the bank even more? Are CA180 cells readily available still?

What's the best way to bulk charge LFP house battery using a van alternator?


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## Emyr (Oct 27, 2016)

brian_ said:


> Weight may be the most common reason given by RV owners for wanting a lithium battery.


That along with more Wh in the same battery compartment and faster charging.


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## Emyr (Oct 27, 2016)

sportcoupe said:


> What's the best way to bulk charge LFP house battery using a van alternator?


Don't. Save fuel and use a mains charger since LFP should accept a faster charge rate than Lead-based chemistries.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> That's for sportcoupe to decide, but I think that weight is a significant concern for such a large battery in a small RV. Weight (and weight distribution) is always a concern in RVs, and we're talking about energy storage capacity at least four times as high as is typical for the base configuration of a small RV (which usually has a single 12V lead-acid battery of 80 to 110 Ah capacity), and double the capacity typically carried by large RVs (two GC2 6V, for about 230 Ah @ 12V).
> 
> Weight may be the most common reason given by RV owners for wanting a lithium battery.


The vans I'm looking at have a payload of 4500 pounds. That is a lot available for batteries and creature comforts inside the van.


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## sportcoupe (Oct 19, 2010)

Emyr said:


> Don't. Save fuel and use a mains charger since LFP should accept a faster charge rate than Lead-based chemistries.


I would need a really LONG extension cord. My last trip was almost 8000 miles.


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## Emyr (Oct 27, 2016)

Buildings other than your home contain AC sockets. You could even use an EV-style connector.


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## sportcoupe (Oct 19, 2010)

Emyr said:


> Buildings other than your home contain AC sockets. You could even use an EV-style connector.


You are suggesting it is not possible to be mobile with a LFP 12v battery pack. That's just not true. Mains isn't required while on the road. You expect me to hunt for a plug-in after driving all day in a camper van?

What the heck am I going to do with an EV style connector? Quick charge my 12v pack?


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## brian_ (Feb 7, 2017)

Emyr said:


> Buildings other than your home contain AC sockets. You could even use an EV-style connector.


At an EV charging station? We've had that discussion in this forum, and I think that the consensus is that this would be unacceptable to EV owners. Even using 240 V AC power to run a charger (not trying to fast-charge with high-voltage DC) I'm not sure that the charging station would maintain power when only a few amps are being drawn.

EV charging stations are rare, to say the least, in places where one might want to camp.

Campsites with power are very common... if that is the type of place one wants to camp.


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## john61ct (Feb 25, 2017)

Best for flexibility is to have multiple sources, but with LFP and such high usage, solar would be pretty redundant.

You need a mains charger for the genset anyway, so ready for shore power when you come across it already are you.


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## sportcoupe (Oct 19, 2010)

So driving all day, there's no way to charge LFP house battery? Seems very odd.


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## john61ct (Feb 25, 2017)

Of course if you drive more than a few hours, not even every day, just most days, with a good setup going into a big LFP bank, that covers a lot of usage.

But that is a very unusual usage pattern. For me, I may stay put 2-3 weeks at a time. Limiting factor is usually water.

Are you a logistics owner-operator ?


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## sportcoupe (Oct 19, 2010)

Back to my question then. What is the best way to charge LFP house pack off the alternator while driving? Electronic isolator relay ? Sterling Battery to Battery charger? Something else?


No, I'm not an owner operator. I am a tourist on extended vacations and like to travel. It will also be my daily driver as I am not retired (yet).


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## john61ct (Feb 25, 2017)

Define best.

The keys are:

user-custom adjustability of setpoints

the ability to limit current drawn by the bank so as to prevent damaging overheating

Sterling BB does these, and is portable with the bank, can be used to regulate any old charge source.

No mods to the vehicle.

But you need more than one if 60A is not enough for you

If the vehicle allows the alternator to be adapted to use an external VR, I recommend Balmar's MC-614.

This lets you get the maximum amps out of your alt.

As heat rises, throttles current while keeping voltage at your desired setpoint.

But then every other source needs fancy regulation, and the money spent only applies to that vehicle.


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## brian_ (Feb 7, 2017)

sportcoupe said:


> What is the best way to charge LFP house pack off the alternator while driving? Electronic isolator relay ? Sterling Battery to Battery charger? Something else?


If the same alternator is used for vehicle power and to charge the house battery, you probably won't have sufficient voltage so I think a DC-to-DC charger would be advisable. Certainly a relay-type isolator would be a good idea; that's normal equipment for motorhomes and trailer tow vehicles.

If you have two alternators, with one dedicated to charging the house battery, then an external regulator set to suit the house battery might work well.


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## sportcoupe (Oct 19, 2010)

brian_ said:


> If the same alternator is used for vehicle power and to charge the house battery, you probably won't have sufficient voltage so I think a DC-to-DC charger would be advisable. Certainly a relay-type isolator would be a good idea; that's normal equipment for motorhomes and trailer tow vehicles.
> 
> If you have two alternators, with one dedicated to charging the house battery, then an external regulator set to suit the house battery might work well.


 

Relay-type isolator for motorhomes and trailer tow vehicles but they don't normally use LFP house battery. I'm thinking DC to DC charger is best.


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## sportcoupe (Oct 19, 2010)

john61ct said:


> Define best.
> 
> The keys are:
> 
> ...



Sterling BB has a high power 120 Amp version now. Looks sweet.


https://www.sterling-power-usa.com/...probattc-batterytobatterycharger12vto12v.aspx


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## john61ct (Feb 25, 2017)

Nope, that's their older BBW line, not appropriate for LFP, not user adjustable.

But Charles has stated up to 240A BBs coming out "soon"


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## sportcoupe (Oct 19, 2010)

That's odd because the user manual download has a lifepo4 configuration. 


Charge Absorption Float Min Boost Max Boost
Switch position volts volts volts mins mins
1) Gel I 14.0 13.85 13.7 60 600
2) AGM I 14.1 13.75 13.4 60 480
3) Sealed 14.4 14.15 13.6 120 480
4) Gel II 14.4 14.0 13.8 720 1440
5) AGM II 14.6 14.1 13.7 60 480
6) Flood/open 14.8 14.0 13.3 60 480
7) Calcium 15.1 14.3 13.6 60 360
8) De-sulphation 15.5 0 0 240 240
9) LiFePO4 14.4 13.8 13.8 30 30


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## sportcoupe (Oct 19, 2010)

I've done some long thinking and have changed my electrical loads moving aircon to genny only, mainly because I want a larger BTU unit. Cooking and coffee will be 100% propane. Heating and hot water will be petrol.

House battery can now easily drop to 300Ah and if I go FLA (or AGM), 300w - 400w solar is planned to be the primary charging method.

.


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## john61ct (Feb 25, 2017)

Very sensible.

As long as you are monitoring SoC reasonably well, go ahead and oversize the bank, just do not draw more that what you can put back given conditions.

Not a good idea to add more batts later,

shallower cycling gives longer lifespan, and 

it will tide you over better when conditions are bad.

Although being equipped to pump Bulk charge in via genny in the AM before solar starts will help get back to 100% Full a few days a week.

You can always add more solar later to reduce ICE charging runtime.


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## john61ct (Feb 25, 2017)

sportcoupe said:


> Heating and hot water will be petrol


please share if you found reasonably priced burners


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## sportcoupe (Oct 19, 2010)

john61ct said:


> please share if you found reasonably priced burners


Combo all in one water heater/air heaters are stupid expensive. I don't know why.

Reasonably priced means two separate units.
Air heater: Espar Hydronic II B5S Economy $667
Water heater: Eccotemp L7 Tankless $199


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## brian_ (Feb 7, 2017)

sportcoupe said:


> Cooking and coffee will be 100% propane. Heating and hot water will be petrol.





sportcoupe said:


> Combo all in one water heater/air heaters are stupid expensive. I don't know why.
> 
> Reasonably priced means two separate units.
> Air heater: Espar Hydronic II B5S Economy $667
> Water heater: Eccotemp L7 Tankless $199


You do realize that the Eccotemp is propane, not gasoline, right?  Or did you find a different L7?


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## john61ct (Feb 25, 2017)

No need for an air heater if you rig a water heater aka hydronics, 

will heat the living space via air exchanger, aka radiators

as well as provide hot water at the same time.

Usually tied into the engine block coolant loop


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## sportcoupe (Oct 19, 2010)

brian_ said:


> You do realize that the Eccotemp is propane, not gasoline, right?  Or did you find a different L7?


Yes and I'll have propane for coffee and cooking already. I can't find a better option for hot water.


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## sportcoupe (Oct 19, 2010)

john61ct said:


> No need for an air heater if you rig a water heater aka hydronics,
> 
> will heat the living space via air exchanger, aka radiators
> 
> ...


If you're talking Truma, those things are $4500


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## john61ct (Feb 25, 2017)

Espar's the one I usually see

I assume also Webasto, Planar

maybe some Chinese knockoffs now, cheap enough buy an extra for a spare?

Some say they adapt the Ecco style instant propane as above, but likely not as fuel efficient

My main point is no need for both space hydronics and HWS the functions should be combined, and integrated into the engine block.


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## sportcoupe (Oct 19, 2010)

The combined air/hot water Espar hydronic systems I see are either $4000 or diesel or both. 

I do not see a single heating solution for air and water in a gasoline (petrol) van. I don't have any rv experience though. I'd like to use propane for cooking only as it's not exactly the cheapest and most plentiful fuel I have available. Gasoline is.


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## john61ct (Feb 25, 2017)

You mentioned the Espar Hydronic II, choose the right model as your base.

For good value, figure out how to hook it up yourself, ideally not just online, but get a pro that charges a reasonable rate to help design, source parts.

But actual installation work is basic plumbing, save a lot doing that yourself.

Skoolie forum has some very knowledgeable guys posted howtos with pics, links to parts.

But yes not cheap if you want a whole complex setup like that all done for you, parts well under half the labor charges.


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## john61ct (Feb 25, 2017)

Note in hydronics, the primary sources only heat the liquid.

Exchangers then output that heat, liquid to air, aka radiators for the air space, liquid to liquid for HWS.

Space heating can be passive, e.g. pipes embedded in the floor, radiator mounted on the wall, or active fans like those bus heaters.


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## sportcoupe (Oct 19, 2010)

john61ct said:


> You mentioned the Espar Hydronic II, choose the right model as your base.


Duh me. I thought that one was ONLY air and not water. I had to take a double take look at it.

Having never installed one, I will research long before I drop $1500. It's still a lot of money, but it runs entirely on gasoline for one model. That's nice.


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## sportcoupe (Oct 19, 2010)

Update from OP.

It's been months. My special order new cargo van arrived and I made my battery decision. I went with a Lifeline GPL-8DL 255ah AGM battery for the house battery for the camper conversion.

Arrived in 2 days after ordering. Free shipping.

https://batteryguys.com/products/lifeline-gpl-8dl


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## john61ct (Feb 25, 2017)

I take it you're a strapping youngfella?


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## sportcoupe (Oct 19, 2010)

51

Two person lift into van. I easily slide the battery to it's forever home.


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