# Cheap lithium



## evmetro (Apr 9, 2012)

Does anybody here have any experience good or bad buying cheaper cells? I understand that we typically get what we pay for, but am interested in getting a less expensive pack. Would still like to maintain 3c capabilities with 5 to 7c pulses.


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## frodus (Apr 12, 2008)

cheaper than what though?

Need to know what you're comparing to?


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## Matter45 (Jan 2, 2013)

Yes we do not know your details, but ill give a quick run down.

the first thing you must do is convert the amount of energy that the battery can hold in watts. AH x nominal voltage will get you this result.

Then, look at the price, divide the price by total watts, and it should give you the price tag per watt. In todays world a good guideline is 50 cents a watt(AUS dollar, I live in Australia). There are cheaper ones out there, just make sure someone else has used them with no problems before jumping the gun. Also PCM is important as well, especially if you are building a custom pack. Balance charging is a must, BMS for that matter is a must for lithuim ion batteries.

If your not good with electrical engineering, then its best to buy a pack that comes with a BMS (battery management system).

So, as an overview. 50 cents per watt is a good guideline. If anyone out there buys lithium Ion batteries cheaper and are reliable PLEASE state it out.


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## njloof (Nov 21, 2011)

Not to be pedantic, but that's 50 cents a watt-hour.

And that's a little high in the US, despite the conversion rate. I paid roughly 40 (US) cents a watt-hour for CALBs recently.


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## Matter45 (Jan 2, 2013)

njloof said:


> Not to be pedantic, but that's 50 cents a watt-hour.
> 
> And that's a little high in the US, despite the conversion rate. I paid roughly 40 (US) cents a watt-hour for CALBs recently.


Yes watt hours sorry. And yes I wish I lived in America!

Care to share a link for those CALBs?


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## ricklearned (Mar 3, 2012)

I bought some Winston's for $0.34 per Watt hr. Here is the link.:

http://www.balqon.com/store.php#!/~/category/id=2736690&offset=0&sort=priceAsc

I have heard that the CALBs have better performance.


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## Matter45 (Jan 2, 2013)

ricklearned said:


> I bought some Winston's for $0.34 per Watt hr. Here is the link.:
> 
> http://www.balqon.com/store.php#!/~/category/id=2736690&offset=0&sort=priceAsc
> 
> I have heard that the CALBs have better performance.


Ricklearned, U LEGEND!


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## jackhyq (Nov 3, 2008)

frodus said:


> cheaper than what though?
> 
> Need to know what you're comparing to?


You're right !


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## PStechPaul (May 1, 2012)

I found some Lithium cells on eBay for $0.22/Wh:
http://www.ebay.com/itm/20-Pcs-1865...geable-battery-silver-Tab-W-Tab-/150971877317

This is a pack of 20 cells, 3.7V, 3600 mAhr, for $58 including free shipping from Hong Kong. That would give me 74 volts and 273 Wh. I'd really like to get enough cells to run a VFD at 230 VAC, which would take four packs for 296 VDC and about 1065 Wh, for $240. I think this would work well for my electric tractor project, which uses a 2 HP (1500W) motor, which I have shown to work at about 400 watts from a 12V or 24V battery through a step-up converter. So I should be able to run it for 2-3 hours with such a battery pack, and at least 1/2 hour of hard use actually mowing or plowing. 

If that works, I might get a second set for 600 VDC to use on a larger tractor for which I already have a 5 HP motor and a 7.5 HP VFD. I figure I could overclock it to get as much as 10 HP (7.5 kW) and the 2000 watthour battery pack should be able to handle it for short durations at 4C. Most lawn and garden tractor conversions seem to report actual average power usage of about 3 HP (2.2 kW) for mowing, so I should get almost an hour of run time, which is plenty.

This would also provide a reality check for my possible future roadworthy EV, with probably a 20 HP motor. I should be able to get the motor and controller working with this 2 kVA battery pack, just enough to go a few miles. Then I can bite the bully and go for a "real" battery pack, probably 100 cells of 40 Ah (130 Wh) capacity, which might give me 30-40 mile range. If I can get these cells for $0.34/Wh, my battery pack would cost about $4500.

Hasa anyone had experience with these or other similar cells at this price? Or is there a better source of LiFePO4 at about 3-5 Ah capacity for my initial trials? Thanks!


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## Siwastaja (Aug 1, 2012)

PStechPaul said:


> I found some Lithium cells on eBay for $0.22/Wh:
> http://www.ebay.com/itm/20-Pcs-1865...geable-battery-silver-Tab-W-Tab-/150971877317
> 
> This is a pack of 20 cells, 3.7V, 3600 mAhr,


Please note that those are probably the "cheapest" LiCoO2 chemistry. 2000 cycles may be a bit optimistic... Expect 500 cycles, and a 4-year calendar life, and maybe you don't get disappointed.

Those probably won't have good discharge rates (internal resistance), so you would need a large pack anyway to overcome that. If you want a small (and short-lived) pack, go to RC lipo.

I fear it's hard to beat LiFePO4 prismatics in price if you calculate the actual cost per year of use. I wouldn't consider using these short-lived, low discharge rated cells unless they are much cheaper in price. But I'm pretty sure you would get some volume discount from these Chinese sellers by simply asking them in Ebay.


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## Ziggythewiz (May 16, 2010)

Especially if they don't even have a brand. Those look like UltraFires, which are known to live up to their name, but if they don't even have that label maybe they're even cheaper knockoffs.


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## PStechPaul (May 1, 2012)

It might be worthwhile to get a couple of them for $6 or so and test them thoroughly, which will be one function of the BMS I plan to build. The possibility of fire is an important point, however, and if I can get good LiFePO4 for under $0.40/Wh then it would not be worth the risk. The same company has 18650 LiFePO4 cells for about $0.61/Wh:
http://www.ebay.com/itm/20-Pcs-1865...m-battery-Blue-Flat-Top-LiFePo4-/150969843917

LiFePO4 from Hobby King seem to be about $0.80/Wh for small packs. I bought some LiPo from them awhile back for $0.31/Wh. But shipping was very expensive $45/2kG.

The Balqon website shows their smallest LiFePO4 as 40 Ah for $44 or $0.34/Wh. That's a good price but for my purposes I want no more than 10 Ah. With that I could get 320 volts from 100 cells and 3.2 kWh for a little over $1000. Looks like I need to risk the LiPo cells or build a DC-DC booster. 

Or I can use the 12V 12 Ah SLAs like I bought for $20 each. I'd need 24 of them which would be $480 and they would give me 3.5 kWh with a weight of about 288 pounds. They would probably be much safer and the weight would actually be good for a tractor.


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## dtbaker (Jan 5, 2008)

evmetro said:


> Does anybody here have any experience good or bad buying cheaper cells? I understand that we typically get what we pay for, but am interested in getting a less expensive pack. Would still like to maintain 3c capabilities with 5 to 7c pulses.



cheapest reliable source at the moment seems to be balqon.com if you can wait for the boat. most reliable in stock seems to be calibpower.com for CALBs.


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## SimonRafferty (Apr 13, 2009)

The Balqon cells say they are rated at less than 3C discharge - which seems a bit meagre! 
Are there any other good value options with closer to 10C rating?

My motor will happily draw 500A at 150v (180v nominal Lead Acid, drops to 150v at full power) - and I dare say more if the batteries could deliver it! I'd like 60Ah cells, but I don't think I could live with 180A max even with the lower sag under load.

Si


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## Ziggythewiz (May 16, 2010)

Simon, I'm sure you've seen the new Calb CAs...they may cost ~20% more (than Balqon), but they certainly put out.


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## dtbaker (Jan 5, 2008)

SimonRafferty said:


> The Balqon cells say they are rated at less than 3C discharge - which seems a bit meagre!
> Are there any other good value options with closer to 10C rating?
> 
> My motor will happily draw 500A at 150v (180v nominal Lead Acid, drops to 150v at full power) - and I dare say more if the batteries could deliver it! I'd like 60Ah cells, but I don't think I could live with 180A max even with the lower sag under load.
> ...



Balqon is not the brand of battery, they are just the distributor. The Winstons (used to be Thunderskies) had a 3C continuous rating, and 'short' pulls 10-30 seconds of 5C were supposed to be fine. This is pretty good for normal driving around town where you may need/want 500amps for 10 seconds accellerating.... but then maintain speed around 100-200 amps.

If you want more performance, the new gray CALBs are supposed to handle 5C continuous, and 10C pulls.... they cost more.... After that you have to go to pouch or cylindrical for max output for extended pulls like in racing.


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## Ziggythewiz (May 16, 2010)

dtbaker said:


> If you want more performance, the new gray CALBs are supposed to handle 5C continuous, and 10C pulls


Have you seen a spec sheet for that?


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## dtbaker (Jan 5, 2008)

Ziggythewiz said:


> Have you seen a spec sheet for that?


I have not gone looking to verify, but I recall seeing that Jack Ricard tested and is selling them thru his EVTV shop as capable of 10C burst output...


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## evmetro (Apr 9, 2012)

Lots of good info here. I was getting worried that I would have to go through a lot more to translate what cheap batteries are. We compare them to expensive ones if we must compare them to something, and they probably aren't as good as expensive ones. They get your car moving and they weigh a whole lot less than lead... thanks for the responses.


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## Ziggythewiz (May 16, 2010)

Ok, yeah, I've seen Jack's tests, but there's a difference between cycling a cell a few times at 12C and the manufacturer saying that it's okay and you'll still get thousands of cycles. All I've seen so far is the 2C on the sheet, which we assume is continuous, as well as too conservative.


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## dtbaker (Jan 5, 2008)

Ziggythewiz said:


> Ok, yeah, I've seen Jack's tests, but there's a difference between cycling a cell a few times at 12C and the manufacturer saying that it's okay and you'll still get thousands of cycles. All I've seen so far is the 2C on the sheet, which we assume is continuous, as well as too conservative.


yeah.... who knows what 'real use' will show. In my Swift I know that max pull is limited by the wimpy curtis 1221 controller. so that will eventually be a great datapoint for thunderskies. They rarely get discharged below 50%, so cycle life should be on the high side.

Miata on the other hand will be testing the blue CALBs hard with the zilla 1k dialed up and my inability to resist enjoying every amp from stop lights and when opportunity presents for the occasional romp.... we'll see what kind of life I get from them. They MAY be saved by the briefness of accel required to get up to speed, and relatively low DOD I expect around town most of the time.


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## Matter45 (Jan 2, 2013)

Ziggythewiz said:


> Simon, I'm sure you've seen the new Calb CAs...they may cost ~20% more (than Balqon), but they certainly put out.


Just like your mum does! HA HA


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## SimonRafferty (Apr 13, 2009)

I've only just started looking seriously at Lithium. I've been put off by the number of stories of people buying cells from China that turn out to be rubbish. I'd heard fewer horror stories recently - so figure I'm less likely to be a victim!

At least with Lead Acid, you can walk in to a store and be pretty sure it will do what it says on the tin!

I don't actually 'need' 500A - but since the motor & controller are capable of sinking that it seems daft not to spec the batteries to deliver the performance!

On my way to work, I need to turn right (across the flow of traffic in the UK) while climbing a steep (20%) hill. You have to be quick to dart between the gaps in the traffic - and this draws the full 500A. Rest of the time probably only 50 to 200A.

Si


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## dtbaker (Jan 5, 2008)

there are some questionable cells out there... lower quality control, higher internal resistance, etc.

winston, sinopoly seem to be dependable and 'good' prismatics rated for the occasional 5C pull. you can get winstons for about $1.10/ah from balqon.com, but might have to wait for a container to come in.

CALBs seem to be consistantly better with lower internal resistance, and the new gray ones are even better, although more expensive than winstons. try calibpower.com . 

In the long run, if cycle life pans out, the prismatics will be far less expensive than the several sets of lead you'd need to go the same miles.... In the short run, the prismatics are way lighter, a little smaller, sag less, charge more efficiently, and perform way better than similar lead pack.


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## SimonRafferty (Apr 13, 2009)

dtbaker said:


> In the long run, if cycle life pans out, the prismatics will be far less expensive than the several sets of lead you'd need to go the same miles.... In the short run, the prismatics are way lighter, a little smaller, sag less, charge more efficiently, and perform way better than similar lead pack.


You're probably right! Though, I'm still running the set of batteries bought from a Junk Yard for $5 each. They were Red Top Optimas fitted to Jeeps and replaced by a dealer - then junked. I just visited every day with a battery tester and bought any that were OK. They have now done 770 (11000 miles) cycles to 50% SOC using my open source charger.
For the first couple of years they were getting better & better (through being charged nicely) but are now getting worse!
I doubt Lithium can compete with that! I think Lead Acid are better than most people give credit for - so long as you treat them well.

Their replacements will likely be Lithium though!

Si


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## dtbaker (Jan 5, 2008)

SimonRafferty said:


> You're probably right! Though, I'm still running the set of batteries bought from a Junk Yard for $5 each. ... now done 770 (11000 miles) cycles to 50% SOC using my open source charger.
> 
> Their replacements will likely be Lithium though!
> 
> Si


getting 700 cycles out of lead is pretty darn good. 50%DOD probably helped a lot. The LiFePO4 prismatics *should* get over 2000 cycles at 70%DOD, and who knows how many if treated 'well' and only taken to 50%DOD most of the time.


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## Ziggythewiz (May 16, 2010)

Can't beat the junk yard, but in much of the US it's illegal to take anything out. We only fill them.


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## SimonRafferty (Apr 13, 2009)

Ziggythewiz said:


> Can't beat the junk yard, but in much of the US it's illegal to take anything out. We only fill them.


That sucks! most of my best purchases have been from Junk Yards - including my Motor & Controller which came from a Hybrid Bus! 

Sadly I missed the 2Kwh worth of Ultra-Capacitors and 50kwh of Lithium cells the day before! 

The only problem with Lithium is the £5k up front cost!

Si


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## SimonRafferty (Apr 13, 2009)

The winston batteries look good!
Roughly £2800 + tax + delivery = £4000 for 58 x 60Ah (12kwh).

http://en.winston-battery.com/index.php/products/power-battery/item/wb-lyp60aha?category_id=182
If the spec is to be believed, they will sustain 5,000 cycles to 70% DOD and about 8,000 to 50% DOD.
The capacity of these is lower (60Ah instead of 80Ah with my lead acid), so my 50% DOD would be 66% on the lithium.

They also say 3C with 20C impulse so 180A with 1200A impulse which is about right. 

I could fit an additional 30 cells into the existing battery enclosures - so I could run 280v 17kwh, 330kw peak - I could burn some tires with that!

So roughly the same cost for the same usable capacity as Lead Acid but exactly half the weight and 5x the cycle life (which comes out as 15 years - which I doubt somehow!).

I'm sold - just need to save up some!

Si


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## Ziggythewiz (May 16, 2010)

SimonRafferty said:


> about 8,000 to 50% DOD.


I've heard the others, but where'd you see that spec?


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## palmer_md (Jul 22, 2011)

Ziggythewiz said:


> I've heard the others, but where'd you see that spec?


it is shown on the second curve on the link above. It actually looks better than that. Seems all the points come from the 3.0v line which would make it 

78% = 3000 (which means 80% is slightly less than 3000)
70% = 5000 (matches)
60% = 8000 (not listed elsewhere, but this looks great)

you might be able to infer that 50% is much more...perhaps 9-10k.


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## Ziggythewiz (May 16, 2010)

Oh...okay. That chart brings up the age old question of what the heck do manufacturers mean?

We usually interpret the numbers in the spec to mean you can discharge the cell to 80% DOD 3000 times (we assume before it reaches 80% of sticker capacity) or to 70% 5000 times (we assume before it reaches 80% of sticker capacity, but maybe they mean 70%).

What that chart appears to show is that if you always cycle the cells at 100%, you'll get at least the sticker capacity for the first 1000 cycles, then you're down to 80% of sticker by 5000 full cycles, etc.


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## SimonRafferty (Apr 13, 2009)

It was an educated guess.

I plotted the three figures given on a graph, extended the likely path of the curve through 50% DOD and unless the curve has a sharp kink in the middle, it crosses between 8000 and 10000 cycles. 10k seemed unlikely so I quoted the more probable end of the spectrum.

Si


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## Ziggythewiz (May 16, 2010)

Understood. I just hadn't looked at the graph close enough to realize it was showing cycle life.

If we can get in the real world what that chart and other info implies, we could pass our cells on to our grandkids along with our motors.

If you only use 30 AH of 60 (1/2 cycle), can you get 25,000 cycles before it fails (falls below 30AH)?


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## Siwastaja (Aug 1, 2012)

Lithium indeed goes pretty much up in cycle rating when DOD% is reduced, just like lead does. I have seen a paper where tens (or was it hundreds) of thousands cycles were actually tested by discharging and charging within a small SOC window.

Note that when comparing lead Ah to lithium Ah, you also need to include Peukert effect in the case of lead. Not much difference if you were running a large lead pack, but if you had a small lead pack and were running it near its limit, you may actually get only about 50 Ah out of your 80 Ah pack. Add your 50% DOD on the top of this and you get 25...30 Ah out. 

With LiFePO4, you have no reason to stay well below 70% DOD all the time -- the cycle life will be so high you'll have some other reason to replace the pack in 10 - 15 years anyway, either the calendar life of the battery starting to take its toll (especially in warm regions), or just some new fancy battery tech being available.

It's wise to use lead acid only if you get used batteries for free or nearly for free, and if you don't need long range. This is also wise from the recycling/environment perspective as these batteries would otherwise be useless junk.


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## PStechPaul (May 1, 2012)

Are there any figures on the total Wh delivery of various chemistries based on DOD? Obviously you can get at least 5 times as many charge/discharge cycles at 10% DOD compared to 50% DOD, but the same total Wh will be transferred from the charger to the EV.


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## Matter45 (Jan 2, 2013)

whats the 80% DOD voltage on a CAB?


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## Siwastaja (Aug 1, 2012)

Matter45 said:


> whats the 80% DOD voltage on a CAB?


Nothing. Voltage cannot be used to derive state of charge or depth of discharge.

Open-circuit voltage of a battery that has been at rest for some time has relation to SoC, but even this is only an approximation, and has little practical use.

The only way to know the SoC (and DoD) would be to measure current and count ampere-hours gone in or out (integrate current over time). Then divide this charge by the cell capacity.


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## Matter45 (Jan 2, 2013)

Siwastaja said:


> Nothing. Voltage cannot be used to derive state of charge or depth of discharge.
> 
> Open-circuit voltage of a battery that has been at rest for some time has relation to SoC, but even this is only an approximation, and has little practical use.
> 
> The only way to know the SoC (and DoD) would be to measure current and count ampere-hours gone in or out (integrate current over time). Then divide this charge by the cell capacity.


Sorry I meant when charging, what voltage do you go up to on a CAB to reach 80% capacity?


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## Ziggythewiz (May 16, 2010)

It depends what current you're charging at.


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## tomofreno (Mar 3, 2009)

Ziggythewiz said:


> It depends what current you're charging at.


and the pack temperature.


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