# Highest AH 12V battery



## vpoppv (Jul 27, 2009)

Brabus said:


> I hope this is okay to ask here.
> 
> I found this forum by searching about A123 batteries, then upon further reading through the forum I read about LFP batteries. To my amazement they go up to an astonishing number of amp/hours (granted the higher the more costly).
> 
> ...


 Maybe I'm missing something in my thought process, but if you are after simple amp hours: two six volt Trojans would be a good bet at 220 Ah each (well, in series that would still be 220 Ah total). Lithium sure is awesome, but there SO many posts about charging these things that it's a nightmare I wouldn't want to get myself into even if I HAD the money....


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## Brabus (Nov 21, 2009)

vpoppv said:


> Maybe I'm missing something in my thought process, but if you are after simple amp hours: two six volt Trojans would be a good bet at 220 Ah each (well, in series that would still be 220 Ah total). Lithium sure is awesome, but there SO many posts about charging these things that it's a nightmare I wouldn't want to get myself into even if I HAD the money....


Thank you for the response. 

The battery would be connected to my internal combustion engine. I assume it would charge like any other battery via the ICE engine. Or are you saying there are charging problems with these batteries, i.e. the batteries themselves have technical issues. 

Like I saw this post about the improvement in the life cycle of a LFP 160AH battery.

* Cycle life 80% DOD from 1000 to 3000, and 70% DOD from 2000 to 5000!

And another one after that talking about 8,000 life cycles. I've read that lead-acid batteries not only do they not have a long life cycle but the available AH degrades rapidly overtime.

My 5 perceived Lithium battery advantages:

a high life cycle
charges relatively quickly
smaller & lighter
higher AH over the life of the battery
No lead

I noticed Thundersky had 12 volt versions which according to this forum they are solid one piece. Here's a link to them, but I didn't see these available to buy in the U.S., so I'm looking at the other options that seem more readily available. http://www.thunder-sky.com/products_en.asp?fid=&fid2=&page=12 


I was surprised that this guy started his car using just 4 A123 batteries. http://www.youtube.com/watch?v=qcvmvrmTMMk


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## vpoppv (Jul 27, 2009)

Brabus,
I don't know enough about Lithium to give any advice on THAT part of it. I just know that some lead/acid batteries can pack a bunch of Ah, are readily available, and are basically plug n play. From all I have been reading (and not understanding), I think slapping in a Lithium battery as your starting battery will need some sort of monitoring system and I don't know if your vehicle's alternator can charge it without some sort of modification. I bet if you title a post about using lithium as a starting battery, someone who knows something about it will be able to answer that. I know there are companies that sell a 12v battery for drag race cars that are Lithium, but they have a charger you need to buy with it (I don't think that drag race cars use an alternator, but, again, I could be wrong. I'm sure someone will come along and tell me ).

http://4xspower.com/products/



Brabus said:


> Thank you for the response.
> 
> The battery would be connected to my internal combustion engine. I assume it would charge like any other battery via the ICE engine. Or are you saying there are charging problems with these batteries, i.e. the batteries themselves have technical issues.
> 
> ...


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## Brabus (Nov 21, 2009)

vpoppv said:


> I think slapping in a Lithium battery as your starting battery will need some sort of monitoring system and I don't know if your vehicle's alternator can charge it without some sort of modification.


The vehicle has a 150 amp alternator, but I don't know whether that's capable of keeping such a high capacity 12v battery charged. I've looked at lead-acid/AGM batteries that go all the way up to 230 for AGM and 260 for lead-acid. I do know the AGMs keep the amp hours significantly better over cycle usage than lead-acid.

http://www.difflock.com/diffmag/issue21/battery/gel-agm.gif

I suspect lithium does far better.


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## Woodsmith (Jun 5, 2008)

If space isn't an issue and you need to have deep discharge for something and also a starting battery then I would be tempted to get a good 12v automotive starting battery in lead acid and then installing a split charge system to charge a deep discharge second 12v lead acid battery to supply the deep discharge needs.

This sort of system is often used by off road drivers so that they have a good starting battery and a good winch battery as the needs are so different.


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## MN Driver (Sep 29, 2009)

After seeing his video months ago when I saw it the first time, I was surprised how much power those A123 cells could dish out too.

The funny thing about this is last week I took apart my booster pack that I've kept in my trunk because it lost all capacity suddenly, I put it on a charge and it would show up completely full at 14.5 volts but would pull no amps, I would then turn on the built-in compressor and it would barely turn the air compressor and the voltage would sit below 10 volts, back on the charge it would shoot right up. The battery was fine a few months before when I used its compressor to help someone who had a low tire when it was convenient to use and it charged up fine then, so it had a sudden death that I'm not aware of. Either way, with winter coming I pulled its 17.2Ah SLA out and got a $55 replacement that was 18Ah Werker that was a direct size fit. I figured the battery would be $40 so I cringed a little as I handed over the money thinking about how I could get a starting battery for that much, but knowing that the light, compressor, and jump starting pack has helped many so far other than me, I still wanted this pack.

As I drove home, I thought about the $17 8Ah Headway cells that can pump out 20C with some people drag racing and pulling even more than they are rated for short drag runs and I figured for the 2 seconds it would take to crank an engine this might not be a bad idea. After I got home I measured things up and the inside of the booster pack could take 8 of those cells, so I could run 2 strings of 4 parallel for a 12.8 volt nominal 16Ah pack rated at 320 amps, which I know it could do more for a few seconds which is likely enough to start a SUV in anything but the absolute worst conditions. ...since my current car only need a battery with 310CCA according to its specs, I could get away with a single string of 4 cells and I'm sure it would be enough to start the car because I don't really think it would pull 310 amps to start it and the impulse abilities likely can stretch enough to get the engine started. I wouldn't have to worry about charging it up every 3 months either and since I can monitor it closely when in use I know that it won't be running dead so no real need for a BMS or anything like that, I could manually charge it after use on a per-cell basis if I need to.


...back on topic, I nearly wrote a novel about a personal story based on the video link you posted...

You could use a Lithium battery but if you ever left your lights on and that battery was drained to the point where it can't start your vehicle, just like how it happens to all of us from time to time, your battery is going to be shot unless you have some sort of disconnect for when the voltage drops below its threshold cutoff voltage. You would want to have some form of battery disconnect in case the battery dropped below a certain voltage, but you would have to have a disconnect that won't operate when you are cranking the engine over since that is when you need the power and the momentary sag shouldn't be an issue for a second or two.

The lithium battery is going to be much more expensive than multiple lead packs would be if you needed to replace a few.

...but it all depends, you didn't mention what you were using this for, you want high Ah but what are you using it for. If you are just using it as a cranking battery, the high storage capacity will serve you no additional use. If you are using this to provide lighting in your camper and you plan to cycle this battery up and down a whole bunch, this starts to make more sense. I think I'd rather try and find two 220Ah 6 volt batteries IMO, even if they only give say 150Ah in a 1 hour discharge environment than getting 4 160Ah cells if the 4 160Ah lithium cells will end up being $775 and a large single lead battery will be less than a quarter the cost I would figure(although not quite the same capacity but still respectable). Larger lead would be proportionately more expensive. It all depends how deep and how often you cycle them before you really know if it is worth it on a monetary basis. Lead acid batteries get recycled, the lead will end up being repurposed so I don't see it being too big of a deal for using it as a matter of environmental concern since it will be recycled.

With some insight on how you plan to use your pack, we could better advise you to if this is a good idea or not, but IMO it is pricey for use as a starting battery if you want 160Ah out of it.

Would a 160Ah 4 cell Thundersky pack start a vehicle? Yes
Is it the most cost effective? It all depends on how you use it, it might very well be. Just don't let all of the cells in the pack drain below 2.5 volts, to be safe keep them around 2.8 volts per cell as voltage will drop like a rock when they are discharged.

As far as options, you've got various options with the Thunder Sky LiFePO4 cells, with lead there are 6 volt 220Ah batteries that you could put 2 in series to make a 12 volt battery which could very well last a long time if you get a high quality brand. I don't know what the cost of a high quality brand 220Ah battery is though.


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## Brabus (Nov 21, 2009)

I was hoping to avoid explaining the application as it would lead to a long post that likely would be so long that most people wouldn't want to take the time to read and at worst confuse the situation, however I'll post it anyway.

Thank you so far for your responses, they've been very helpful especially the voltage disconnect monitor for lithium batteries.

Woodsmith, What you suggested is exactly how the vehicle is configured from Winnebago, i.e. a starting battery in the engine compartment with a deep cycle in the rear of the vehicle. The deep cycle in the rear is charged via a 20 amp auxillary charger powered through the engine. Thus both starter and deep cycle are charged while driving. However, this setup provided marginal energy on extended trips.

I have given the stock 20 amp auxillary charger away as I plan to install a higher amp charger with a large rear battery bank to maintain an 500 watt air conditioner. I plan on installing a 2800 watt 110v or 2500 watt 220v cummins-onan generator in the engine compartment. It will require some fabrication to make the fit for the minimum compartment size 12.52" x 18.20" x 20.46" (I haven't found one smaller, and this one has an remote muffler). 

I prefer the location of the engine compartment area as there is room & it would muffle the sound from the interior of the vehicle. The 220 volt version is quieter and consumes less fuel than the 110volt version. I'm leaning more towards the 220 volt system. http://www.cumminsonan.com/rv/products/gasoline/compare?gensetId=122

Therefore the battery for the engine would be in the cabin area of the camper. This is where it gets confusing for me. What size deep cycle battery should I use for the engine and should I get one that is high amp hour to serve some of the electrical needs of the camper. Or should I get a normal size battery which would fit under the dash and leave the big energy demands to the large battery bank that I will have in the rear of the vehicle. In other words, the front engine battery and rear deep cycle setup like most RVs. 

And before you say, well just do what other RVs do....well, all RVs use air conditioners that run on generators, they do not run on battery banks as they consume a couple thousand watts to run to cool even camper vans. This one will have a small household air conditioner that consumes a max of 500 watts. A very different application and at night I want to run it off the rear battery banks as I can have it on low settings thus consuming much less wattage. My application/goal is unique.

While the goal is to take as much advantage of the engine energy for the starting battery to recharge a deep cycle 12 volt as possible. I'm also aware that the alternator doesn't charge super large Amp Hour batteries yet I'm not aware what the cut-off should be. It did fine keeping the blue top optima battery with 60AH, yet would it do fine working with an AH two, three or four times that size. Essentially I don't know what the recharge of AH per hour of engine running would be to determine what is worthwhile for maximum deep cycle battery for the front. And even worse, I don't want to burn alternators up. 

So back to my original question, what's the maximum AH can a engine battery be to gain the energy consumed while driving into stored deep cycle energy? The alternator is 150 amps, however when I spoke to an Interstate Battery guy he said it wouldn't charge deep cycles very fast but he didn't know how much was too much in terms of amp hour. Like I'm sure I could go higher than 60 amps, but how much higher is the question that I lack the information. I suspect the answer to my question is how quickly does an engine charge a battery.

I plan to have a large battery bank in the rear that is separate from the engine battery. I hope that helps and doesn't confuse. I've been thinking about doing this for years and well I know less than I should to make it happen.


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## Sunking (Aug 10, 2009)

Largest 12 AH capacity I know of is 375 AH; Surrette 12 MD 375 PM


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## Brabus (Nov 21, 2009)

Sunking said:


> Largest 12 AH capacity I know of is 375 AH; Surrette 12 MD 375 PM


 Thank you. Very interesting. Though I still need to figure out how much charge the ICE engine provides to a battery. Even if the sky is the limit in AH, I can't make a decision on what size I should stop at if I don't know how to calculate how much the engine charges.

--------------------------------------------------------------------------------------------

Anyway, here's some examination of the link you provided in looking at their battery offerings. Apparently they offer a submarine battery at 10,000AH, ha! As for their lead-acid battery offerings they have two series called:

Series 4000 (which I assume would be similar to most lead-acid batteries) which give:
2688 cycles @ 10% DOD
2048 @ 30%
1536 @ 50%
1300 @ ??%

Series 5000 which give:
6600 cycles @ 10% DOD
5040 @ 30%
3840 @ 50%
3300 @ ??%

The only 5,000 series 12 volt is just under a thousand dollars at 357AH @ 272lbs.

That's about 3x the weight/dimensions of a 300AH Lithium, yet I'm sure less than a third of the price. 

The cycle life of a thundersky is

5000 @ 70% DOD
3000 @ 80% DOD

They have much higher AH in lower voltage all the way up to 2430AH, yet weight, cost and ability to maintain a charge would be prohibitive.

Surrette also has some good options for AGM, however I haven't found information on life cycles.

http://www.surrette.com/content/marine-battery-specifications

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Anybody know the charging rate is for an engine battery? I believe it's rather low and that my consideration of these high AH batteries is in vain because of it. But I'm not 100% sure.


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## dataman19 (Oct 7, 2009)

Ok Brabus,
..
You want to use a deep cycle battery to start your RV? I can relate to that - No problem...
You want a higher capacity battery set to power the RV? Still no problem.
Just put bigger batteries in.
..
But wait, you also want to power an Air Conditioner from a Battery bank? To make it simple, just put an inverter ion the battery bank to power the Air Conditioner. But, naturally this will require a larger battery bank, which you plan to install. 
...
To illustrate using an example, I will give you an example of our earlier Computer Server Room Hillbilly (poor man's) UPS (UPS=Uninterruptable Power Source).
..
We hooked up four 245 AHr Deep Cycle Batteries in parallel. We the hooked up a "commercial 120-Amp Battery charger to the batteries. The battery charger being plugged into the 220V Outlet - we had Battery/DC Power when the power was on, and DC power when the 220VAC was dead (In short we had a seamless Power source). Our servers were powered by Inverters to supply 115VAC to each server Power supply. So the computers were powered up when we had commercial power (ie 220VAC) or not.
..
Why did we use the original AC power supplies? Because we already had them, and 12VDC/24VDC or even 48VDC Powered PC Power Supplies would cost ten times what the batteries and Inverters cost.
..
So Brabus - how about this:::
..
Re locate your vehicle battery to whatever compartment you want to. Use 4GA or even 2GA welding wire. You may or may not choose to use the original battery or a deep cycle - either choice is good. But I caution you. Your Vehicle starting Battery should never be used as an accessory power battery in an RV... If you do you run the risk of a( draining the battery too low to start the RV (in which case you will have to push start it - oh no dah ohhh - RV's have automatic transmissions)...
..
The reason that a starting battery does not have a lot of long term capacity is two fold: 1st: It doesn't need it - it jsut starts the vehicle. 2nd - If it had a lot of long term capacity - when the vehicle was hard to start and had some electrical issues with the ignition - some uninformed individuals would keep on cranking the starter to force the vehicle to start. This would result in ober-heating and burning up the vehicle started (at the least). It could also result in an engine fire when the overheated starter catches fire or ignites residual oil in the engine compartment. Neither one good...
..
So how about modifying your RV's AC to run on DC? Sound hard? Not really. But you will need an AC tech to charge it (and hopefully to remove and save the refridgerant before modifications).
..
Basically, all you would need is a DC AC Compressor. The rest of the Air Conditioner would remain the same.
..
Here is a DC Air Conditionaer Compressor link:
...
http://www.masterflux.com/products/sierra
..
You will find compressors in all sizes and capacities.
..
If you really want to increase your RV's electrical efficiency, install a DC powered AC system. Then it wouldn't matter whether you were parked and plugged into the campground aAC or not. It would also mean that the AC would run un-interrupted when connecting and disconnecting the external power sources.
..
Then all you need is the Battery capacity..
..
Speaking of batteries....
Battery Charger notes: Most batteries are designed to be charged over a 10-hour rate. In fact the battery in your car only charges at a rate of 40% (peak) and decreases rapidly to 10% of the Amp Hour rating of the battery. So If you car requires 280 Amps for 3-minutes to start - your alternator will need 28 Amps of surplus capacity to charge it back up. Since your car computer runs on about 20-40 Amps, and your accessories could require about 10-25 amps, your headlamps/night lamps would require about 18-32 Amps you are looking at a 78-135 Amp load. In order for your alternator to last very long you would need a 105-amp to 195-amp alternator.
..
Are you seeing the math? If you put a higher capacity Battery System in the Vehicle, you probably will need a stronger alternator. In fact, many people have brought vehicles in to me that had larger batteries installed, and were experiencing long term battery issues. Put in the correct alternator for the batteries and bingo - no problems.
..
This also applies if you install an "auxilliary battery adapter" kit. Especially when you will be utilizing the additional capacity of the new auxilliary battery you install.
..
Need an increased alternator capacity??? I have a link for that too::::
http://www.alternatorparts.com/
...
National Quick Start has made alternator and starter kits for cars for over fourty years. They also rewind alternator windings to increase the alternator capacity radically. Call them up. They are in Michigan
:: Their number is 1-616-785-7990.
..
Need a battery Remote Terminal Post??
..
Try here:::
http://www.pitstopusa.com/detail.aspx?ID=69347
...
Hope all this info helps...
..
Dave Mason
dataman19


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## Brabus (Nov 21, 2009)

dataman19 said:


> put an inverter ion the battery bank to power the Air Conditioner.


When you say "Inverter Ion", do you mean a simple Inverter. I have an inverter which I intend to run the 110v a/c unit. It's a modified-sine wave inverter, however I plan to upgrade to a pure sine wave. I'm not familiar with the term "inverter ion".



dataman19 said:


> We hooked up four 245 AHr Deep Cycle Batteries in parallel. We the hooked up a "commercial 120-Amp Battery charger to the batteries. The battery charger being plugged into the 220V Outlet - we had Battery/DC Power when the power was on, and DC power when the 220VAC was dead (In short we had a seamless Power source). Our servers were powered by Inverters to supply 115VAC to each server Power supply. So the computers were powered up when we had commercial power (ie 220VAC) or not.


The vehicle will rarely be connected to a Landline power source. I haven't made the decision as to whether I want to do the 2800 watt 110 volt Onan generator or the 220 volt 2500 watt Onan generator. While 220volt sounds powerful, due to the low wattage it won't provide more power. Only reason I find it desirable is it consumes slightly less gasoline & is a little quieter. So originally the intention for the batteries is to charge them during daylight hours with the generator and have the generator turned off during night hours running purely on battery power. The idea that I could gain some AH charging through the engine would be nice, however based on what you wrote it seems that I'd need to get a custom made alternator. I suspect your thoughts on simply having a starter battery for the engine and keeping the battery bank for the rear may be the likely route to take.



dataman19 said:


> So how about modifying your RV's AC to run on DC? Sound hard? Not really. But you will need an AC tech to charge it (and hopefully to remove and save the refridgerant before modifications).
> ..
> Basically, all you would need is a DC AC Compressor. The rest of the Air Conditioner would remain the same.
> ..
> ...


I would love to have a 12, 24 or 48 volt air conditioner. I've searched high and low for such. The only thing out there are ice coolers (which use about 20lbs of ice per hour, impractical) and then there are boat systems that use cold ocean water. They have boat and RV 110v systems but they consume nearly double the watts as what a much smaller home 5,000 BTU window unit consumes (500 watts) at a tenth of the retail price. If I could simply swap out the 110volt A/C compressor for a 12/24 volt compressor to run the A/C straight from the batteries instead of through a 12volt to 110volt inverter then I'd do it in a heart beat. Is that what you're saying is possible? If so, then that would eliminate the demand on an inverter.



dataman19 said:


> ..
> Then all you need is the Battery capacity....
> 
> Speaking of batteries....
> ...


True, I am looking for ideal battery capacity. Though a big problem is keeping that battery capacity charged, which is a confusing endeavor. As for charging from the engine, I really don't know what to expect however you'd done a good job at explaining that I can't expect much without a bigger alternator. I was basically told the same thing from a battery rep. yet he said it wouldn't matter how big the alternator was on the vehicle that it wouldn't be enough to keep a high AH battery maintained/charged. It leads me to believe charging a high AH battery bank is likely going to have to happen through the gasoline generator or during the rare occasions when landlines power is available. A 10 hour charging time is a good reference to consider, I suppose anything faster wouldn't be possible with the onan generator size and even if such were available it may run the risk of hurting the battery.




dataman19 said:


> If you put a higher capacity Battery System in the Vehicle, you probably will need a stronger alternator. In fact, many people have brought vehicles in to me that had larger batteries installed, and were experiencing long term battery issues. Put in the correct alternator for the batteries and bingo - no problems.
> ..
> This also applies if you install an "auxilliary battery adapter" kit. Especially when you will be utilizing the additional capacity of the new auxilliary battery you install.
> ..
> ...


I have looked into a bigger alternator and clearly it would have to be a customized item, i.e. not something I can just order online to have my local mechanic install. I wasn't aware that there were custom designed alternator businesses. If it was a partial solution, then I will pursue it. The VW camper actually uses a rather high AMP alternator, Jeep/Range Rover people use the VW Camper alternator to upgrade their smaller alternator. I suspect the better thing may be to just have one large battery bank in the rear with a starter battery from the engine. Use the generator to charge the battery bank in the rear when landline power isn't available. Does that sound like what you're saying?

All this information has been very helpful. I really had no idea how much is involved just to keep a small vehicle cool, fans work in mild climates but hot climates require air conditioning and consuming 45 amps per hour isn't a problem in terms of battery capacity, but keeping it charged everyday without being connected to a Landline is a challenge. Not to mention other electrical items in the vehicle.


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## dataman19 (Oct 7, 2009)

Touche...
I missed the typo "Inverter Ion" should have been" Inverter on the battery pack".
...
As to the size of the alternator for your battery pack... The rep is somewhat right. Most automotive alternators are only rated to about 240-Amps (max current - which equates to a practical 195-Amps).
..
However - National Quick Start has a bolt in Armature that will take the alternator up to over 320-Amps with a 280-Amp continuous duty cycle.
The trade off is that the alternator is slightly bigger.
...
200-Amps continuous duty will charge a 2,000 Amp Hour Battery Bank. It will maintain a 1,200 Ahr Battery bank with an 80-Amps auxiliary load.
..
This is why your original battery isolator on the motor home was a 20-Amp isolator (otherwise known as a 20-Amp Shottky Diode). 20-Amps is sufficient to charge a 200-Ahr Battery (I would bet your battery was a 245-AHr Deep Cycle Battery).
..
We thought about building DC Air Conditioners a few years back. But Air Conditioners will normally run on cheap AC Inverters - and so a $69.00 Harbour Freight Inverter will generally run any small window AC unit - hence no one foresaw the EV craze to put DC AC Compressors into EVs...
..
Now we are setting up an EV Car Company and are in the process of organizing the two companies into one "branded" company.
..
Our goal is to organize in three states (one in the west, One in the Mid South, and One in the North east). Then we will produce at least five models with a range of 100-300 Miles per charge and a @14K to $18K Sticker Price. At least for the Consumer vehicles.
..
Yes we are looking at Lithium Ion - but we are looking at 460-AHr Cells.
..
For our Dept of Defense Project we are looking at 2,500 lb payloads and 4,000 lb towing caps. The Navy Contract is the only stickler (it seems that carrier support vehicles have to be tiny - like mini golf cart sized).
..
Good luck with your Battery Quest.
..
If you lived here in Phoenix, AZ I would gladly lend a helping hand.
..
Incidentaly, Are you looking for Solar Panels for Your RV?
..
I have a source here in Phoenix that has five or six left from their project. They are 170-Watt Panels - he's looking for $500.00 or so per panel.
..
Take care,
Dave Mason
dataman19
[email protected]


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## Sunking (Aug 10, 2009)

You want to rune air conditioning on batteries? 

Let's assume your unit is 1 ton. I suspect for an RV it is much higher. For 1 ton uses about 1500 watts depending on efficiency and you want to run it 8 hours at a 50% duty cycle. Energy consumed = 8 hours x 1500 watts x .5 = 6 Kwh. 

At 12 volts and 50% DOD would require 12,000 wh / 12 volts = 1000 AH 

As for charging the battery off the vehicle alternator depends on the alternator capacity. Most cars have a 60 amp alternator up to 120 Amps. I do not know what size an RV has but you get the idea how long it will take. Doable, but it may require lengthy engine run time. Better off just using a small portable generator from a gas POV.


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## Dolphyn (Nov 17, 2009)

These batteries might be worth a look: http://www.fluxpwr.com/products.html

This is a new company based in California selling 12V LiFePO4 batteries with a built-in battery management system. I don't know how much they will cost, but they are supposed to be available very soon.


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## dtbaker (Jan 5, 2008)

Brabus said:


> I have a ICE Volkswagen van (camper) that I would like to replace the old/near death Optima Blue Top battery (deep cycle/starter) with a much higher capacity 12volt battery. Preferably lithium.


why Li? you have to deal with tightly controlled charge curves and BMS. In your case, why not go with a monster 12v floody like a sweeper battery?
http://www.usbattery.com/usb_us185hcxc.html


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## Brabus (Nov 21, 2009)

Thank you very much for all the responses. It's very much appreciated.



dataman19 said:


> However - National Quick Start has a bolt in Armature that will take the alternator up to over 320-Amps with a 280-Amp continuous duty cycle.
> The trade off is that the alternator is slightly bigger.
> ...
> 200-Amps continuous duty will charge a 2,000 Amp Hour Battery Bank. It will maintain a 1,200 Ahr Battery bank with an 80-Amps auxiliary load.
> ...


I will make some calls this week, because if I can double the alternator amps then that means I can use a bigger amperage auxiliary charger for rear batteries. This would be very good news, because previously I thought this wasn't possible. 





Sunking said:


> You want to rune air conditioning on batteries?
> 
> Let's assume your unit is 1 ton. I suspect for an RV it is much higher. For 1 ton uses about 1500 watts depending on efficiency and you want to run it 8 hours at a 50% duty cycle. Energy consumed = 8 hours x 1500 watts x .5 = 6 Kwh.
> 
> ...


That's true for larger interiors than my application, that's why there aren't any recreational vehicles that do what I'm suggesting, yet that's not true for truckers. Even regular camper vans are double the interior space of my VW camper, therefore they require high wattage. Sportsmobile (which is by far the most customizable camper van on the market describes exactly the problem you describe. They use a Carrier A/C unit that uses about 1500 watts, these carrier units are designed for larger RVs thus the 13,500 BTU.)

http://www.sportsmobile.com/2_sr_heatingcooling.html

However, what I'm suggesting is similar to a no-idle trucking system such as this which I may end up purchasing. I need to research it a bit more. Though part of me wonders if it's simply not a glorified $99 home window air conditioning unit that has had the AC compressor swapped with a 12 volt DC compressor:

http://www.nitesystem.com

These newer designs for Nite Systems came out this year. Previous versions for trucks weren't worth considering, however this unit uses 300 to 636 watts and uses a DC compressor (extremely rare for air conditioning systems) rather than the 1000+ watt systems in RVs/Camper vans/boats/etc. Thanks to no-idle laws, it looks like there is finally a solution. I've been looking into this for about ten years now, and I've tried all sorts of possible solutions, none of which proved practical.

I'm not sure what the size of the alternator is on a tractor-trailer rig. The nite system only recommends 440 AH and then there's a day-system that they sell.



dtbaker said:


> why Li? you have to deal with tightly controlled charge curves and BMS. In your case, why not go with a monster 12v floody like a sweeper battery?
> http://www.usbattery.com/usb_us185hcxc.html


I think that's a nice battery you posted. It's takes up less area than most batteries I have looked at with similar AH.

I was looking at Li, because I'm not familiar with them. Main reason I was fascinated by them was due to the number of charge cycles, ability to maintain their DOD, light weight and area, etc. However, the cost of them are still prohibitively expensive when compared to flood/AGM batteries that they it's not really worth it to me. I've now learned from a previous post that there is a tightly controlled charging curve.


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## Brabus (Nov 21, 2009)

I haven't heard back yet from National Quick Start regarding an alternator for my vehicle. Someone did tell me the following regarding on a VW Eurovan forum about alternatorparts.com's claimed 350 amps. Any thoughts to this would be helpful.

"This is mostly marketing doubletalk.

Alternators are typically rated at *peak* output current. That's what
they can deliver for less than 1 minute, into a nearly dead battery.
This is what you get immediately after the engine starts, when the
battery has been deeply discharged (as from starting a hard-to-start
engine), and the alternator is cold.

This peak output current number is meaningless for recharging a deep
cycle battery for RV use. The output falls very quickly to some much
lower current, as the battery voltage rises (due to being charged) and
the alternator warms up (due to heat produces by its output current). So
what matters is the *sustained* output current (and they don't bother to
tell you that).

More diodes won't improve the sustained output current. That's limited
by the windings inside, and the cooling capacity (main the fan size and
operating RPM).

Car alternators also have terrible efficiency (60-70%). It's hard to
make a generator or alternator with as low an efficiency as the auto
companies manage to produce. An efficient device can't help but be big
and heavy. If you have the room, a truck or bus alternator or generator
is better; but it won't be an easy job in a Eurovan."


..............................

I'm still looking for a more powerful alternator, however from what I'm being told it seems I will need a special alternator voltage regulator similar to that used by marine & big RVs. 

"The regulators control an alternator as a good battery charger by monitoring the battery charging current and voltage to control the alternator to provide a multi-step charging algorithm to recharge the battery as quickly and properly as possible. The alternator itself does not change; the new regulator just holds it at its maximum steady-state output current until the battery is about 80% charged, and then tapers the current off. Some of these regulators are smart enough to start/stop the engine and control its throttle to keep the battery charged with minimum engine running time and fuel consumption."


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## TheAtomicAss (Feb 19, 2009)

Let me see if I get this straight.

You have a VW Microbus RV, (I'm picturing the hippy bus conversions to RV that are comparable to a modern minivan, am I right on the general size, or is it the size that can be properly called Class-C?)

You want air-conditioning in it, had or have a unit that uses 500 watts already, and it's either ready for replacement, or does not have the snuff to cool down the bus?

You're considering an air-conditioner fully thrice the size of what I use to cool my bedroom, to cool a camper that could be parked two abreast in said bedroom.

If I've gotten all the info correct, (this thread is hard to read, and it's not just you, Brabus), then I think some solutions can be had. 

Number one, when considering Lithium batteries, take into consideration they CANNOT be float charged like LA batteries can. You would need some setup that disconnected the batteries from the alternator when they reached full charge.

Second, your choice of air-conditioner, to me at least, sounds unbelievably excessive, both by wattage and by BTU capacity. A suggestion that eliminates the need for a converter, though it does require a little more manual work, is to set up a group of Peltier panels to a heat transfer system. Peltier panels are small wafers, that when electricity is applied, transfer heat in one direction. They're typically used in solid-state electric coolers and small fridges. Most of these run off of 12V DC anyway, so you shed inverter losses which demand a larger battery pack.

Third, almost all cars have room under the hood for a second alternator, VW buses are definitely not excluded from that. A second alternator will remove the concerns of burning up your only alternator, potentially leaving you stranded somewhere.

The required battery capacity can be roughly estimated by setting up whatever cooling system you decide on, with a 120VAC-12VDC transformer taking the place of the batteries, and with the transformer plugged into a Kill-A-Watt. However many watt-hours of energy your setup is reported to use is very close to what you'll need as a minimum for battery capacity, especially if you decide to stick with LA, which does not like deep discharge, despite what it says on the battery.


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## Brabus (Nov 21, 2009)

TheAtomicAss said:


> Let me see if I get this straight.
> 
> You have a VW Microbus RV, (I'm picturing the hippy bus conversions to RV that are comparable to a modern minivan, am I right on the general size, or is it the size that can be properly called Class-C?)


Correct, a VW camper hippy bus about 200 cubic feet. They're larger inside than the 1960s/70s buses, but nonetheless they are about the same size. 



TheAtomicAss said:


> You want air-conditioning in it, had or have a unit that uses 500 watts already, and it's either ready for replacement, or does not have the snuff to cool down the bus?
> 
> Second, your choice of air-conditioner, to me at least, sounds unbelievably excessive, both by wattage and by BTU capacity. A suggestion that eliminates the need for a converter, though it does require a little more manual work, is to set up a group of Peltier panels to a heat transfer system. Peltier panels are small wafers, that when electricity is applied, transfer heat in one direction. They're typically used in solid-state electric coolers and small fridges. Most of these run off of 12V DC anyway, so you shed inverter losses which demand a larger battery pack.


Most camper vans (which are about 450 to 600 cubic feet inside) have air conditioners that consume around 1200 to 1500 watts. They are all based on 110 volt systems and the reason they don't sell air conditioners lower than this is because there aren't any vans smaller than full-size camper vans (i.e., Roadtrek.com; sportsmobile.com, etc>) other than VW buses which they do not come with generators.

Thus the smallest air conditioner I can find are those sold for home use which consume between 500 to 600 watts (5,000 BTUs). One person here suggested converting the AC compressor to a DC compressor to avoid the wasted electricity of an inverter. 

I suspect 500-600 watts is about the right size as the nitesystem.com which is for truckers consumes 636 watts (it's powered through diesel fueled generator that powers a 400-500 AH battery bank). My VW is unleaded gas powered. The nitesystem is new and I do plan to contact them to see whether they'd consider an installation into a VW bus though the generator they use while not very high in watts is about 3 times bigger in size than RV Onan generator of comparable wattage. In other words, the size of the units seem excessively large as the intention is to mount them on the outside of a large truck platform. Essentially, I want to do the same thing as the nitesystem but with minimal excess, i.e. I don't want a huge diesel generator hanging off the rear of the VW bus.

Comparing a metal vehicle (greenhouse-like) to an insulated home (roof, etc) isn't practical. The van is 10 times less insulated as a home. Even without the greenhouse effect, I can put a 1500 watt electric heater in the van at 30 degrees F and it would struggle to maintain a warm temperature inside whereas the same heater would keep a room 10 times the vans size nice and warm. The single-pane windows of the van and such make the small size rather inefficient which is why it requires more energy than say a home of comparable size.There's incredible temp loss and there's only so much insulation will do to keep the vehicle from being a greenhouse. I can insulate the van better but there's only so much you can do to minimize the transfer of heat. More so when it comes to air conditioning as the sun's greenhouse effect is a lot more powerful than keeping heat inside the vehicle during cold winters.



TheAtomicAss said:


> Number one, when considering Lithium batteries, take into consideration they CANNOT be float charged like LA batteries can. You would need some setup that disconnected the batteries from the alternator when they reached full charge.


Primarily, the benefit I see with lithium is a third of the weight per AH yet at an incredible cost for that weight. If I can get away with not needing too much AH then I can avoid the cost of lithium and stick with LA batteries, which I think 500AH is doable in LA without it getting prohibitively heavy though anything above that might lead me to reconsider whether it's practical to carry such weight around. I'm not familiar with the electronics I'd need to purchase to monitor the lithium and the more I look into it, the more it seems the better purchase right now would be lead acid/AGM as lithium battery prices such as the thundersky seem to continue to have significantly decreased in price. I suspect this will continue to be the case as lithium batteries become more common/available.



TheAtomicAss said:


> Third, almost all cars have room under the hood for a second alternator, VW buses are definitely not excluded from that. A second alternator will remove the concerns of burning up your only alternator, potentially leaving you stranded somewhere.


I wasn't aware that this was even possible. I'll look into it. That would be great if I could have a dedicated alternator to recharging the battery bank.



TheAtomicAss said:


> The required battery capacity can be roughly estimated by setting up whatever cooling system you decide on, with a 120VAC-12VDC transformer taking the place of the batteries, and with the transformer plugged into a Kill-A-Watt. However many watt-hours of energy your setup is reported to use is very close to what you'll need as a minimum for battery capacity, especially if you decide to stick with LA, which does not like deep discharge, despite what it says on the battery.


Exactly, I think the biggest challenge is figuring the best way to keep the batteries charged whether it be a generator and/or alternator. Generators are rather noisy and it appears people are saying the batteries should be charged over a 10 hour period. I assume this to mean this would require a generator to run 10 hours out of a 24 hour day. 

I've also considered running the Air Conditioning unit via these 1000 watt generators. They are small 50cc generators (about the same noise level as the 2000 watt generators). 

At any rate, if it takes 10 hours to maintain the charge level of a battery bank per day using a larger 2800 watt generator, then maybe what is better is to forego running an A/C unit off of the batteries. The use of the air conditioner at night would be rather minimal, i.e. it could be on the lowest setting thus using a mere 200 watts at most. At night it could run off a battery bank rather than a generator.

It's not as easy to do as I had hoped. There are a lot of factors to take into consideration and the biggest one seems to be how to recharge the batteries/run something that consumes 550 watts during daylight hours and 200 watts during night hours continuously (consuming less at night as there's minimal greenhouse effect at night).


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## TheAtomicAss (Feb 19, 2009)

Brabus said:


> I wasn't aware that this was even possible. I'll look into it. That would be great if I could have a dedicated alternator to recharging the battery bank.


I forgot to mention, that I am most familiar with this being done with dual electrical systems, as is the case in vehicles with high-power audio systems. In such a situation you have the stock alternator for the lights and starting battery, and the second alternator is exclusive to the accessory battery.



Brabus said:


> Exactly, I think the biggest challenge is figuring the best way to keep the batteries charged whether it be a generator and/or alternator. Generators are rather noisy and it appears people are saying the batteries should be charged over a 10 hour period.


I think most batteries will charge faster than that. 10 hours is probably listed as the time to charge on a bench charger, for the longest possible service life.


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