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BAE-200 Powerwall
#21
Hi . I have 90 of these A123 40v packs. Do not use the bms it is only a high cell burner. Check out my youtube channel..

(06-05-2019, 03:25 PM)FrankZ Wrote: Hi . I have 90 of these A123 40v packs. Do not use the bms it is only a high cell burner. Check out my youtube channel..



(08-26-2018, 05:51 AM)Solexx X Wrote:
(08-24-2018, 05:49 PM)Crimp Daddy Wrote: If you are mixing 14s Lithium Ion and 16s LiFePO4 in parallel, they should be ok together, but I wouldn't let it run wild without testing on both the top end and bottom end of the voltage range to make sure everything agrees.

Using an APC you don't really have much customization of charge termination voltages so do keep a close eye.  Personally I would want to limit both the top end and bottom voltages to try and extend life of the cells and give myself a little runway for saftey.

If you have a multimeter with a USB logging capability or a few CellLog that actually record data, you can capture what is happening during the APCs max charging and float voltages assuming you are charging using the APC and not just using it as an inverter.

No mixing on the same system. Really bad idea. Each system will need their own charge controller and inverter or you will lose capacity to the lowest denominator. This simple math fellas.  Is it possible? Theoretically yes. is it smart? Fuck no.

Id agree. No mixing. Lipo charge and hold voltage .Lifepo4 are like lead acid and have a CC. CV charge . After charging your lipos will continue to charge the Lifepo4 until they reach the float voltage of the Lifepo4s around 3.45/cell.
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#22
That does not sound correct… LiFePO4 is not like lead acid at all.  All lithium chemistries including LiPo, Li-Ion, LiFePO4 have CC/CV charge profiles… lead acid does not.
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#23
(06-05-2019, 05:24 PM)Crimp Daddy Wrote: That does not sound correct… LiFePO4 is not like lead acid at all.  All lithium chemistries including LiPo, Li-Ion, LiFePO4 have CC/CV charge profiles… lead acid does not.

How does lead acid not . A 12v battery is charged at 14.8 constant current until 14.8 is reached then constant voltage until 1A or so then float the rest of the day.  My A123 calls for this charge as well. My lipos do not float at all because the CV is the cutoff and the voltage does not drop from that cutoff. Do you know what I mean?
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#24
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Hello all

I joined the forum primarily to contribute to this thread. Thanks to everyone else who has contributed. I have noticed that these BAE modules are still available from a wide variety of sources and prices are pretty reasonable per kWh so it's worth sharing what we learn so that more folks can use them wisely and well.


I bought a bunch of them (about 50) some time last year through an industrial auction.  Some came gift-wrapped in a Daewoo forklift that the previous owner had (unsafely) hot-rodded in this fashion and some were just in TTC crates on a pallet.  I traced them back to an industrial recycler wheeler dealer type somewhere not too far from here in rural QC but I couldn't get him to cough up his source. He's somehow been getting them from TTC (Toronto Transit) castoffs for some time and I keep seeing his ads on Kijiji and eBay so the flow continues.

My best modules tested at 15Ah (600Wh or 83% of original spec) and some were so crippled by a bad series element that charge and discharge were both severely limited and tested capacity was between 5 and 8Ah (30-45% of original).  All those in the latter category have been tagged for teardown.

Below is a summary of some of my testing results to give an idea of the range one might expect from a random sample of these BAE modules if you got them third or fourth hand or picked them out of the TTC dumpsters yourself.  I suspect that reputable sellers hawking these modules are offering better average condition than mine but I'd wager that nobody is doing full balance discharge and balance charge testing like I did.  I think it's possible that one of these modules could pass a simple charge/discharge capacity test but that one bad series element could be experiencing dangerously high or low voltages.  CAVEAT EMPTOR.




Sidebar: I bought a 1500W 12S balance charger from Chargery as part of this project and it has proved extremely helpful for testing and diagnosis, as well as myriad other charge/discharge/testing functions for virtually every battery chemistry.  Good tool for this kind of work and I find I use it all the time.  For the mystery secondhand BAE modules it is crucial to separating the "usable as is" from those that need to be broken down.

So far I've done a lot of testing to find the good ones and shelve the bad for later and I also built one big(ish) pack out of my 14 best modules, all paralleled for a 12S112P configuration.  This pack powers an electric cultivating tractor here on our organic vegetable farm and it was the reason behind the purchase of these BAE cells.  There are videos on YouTube but as a newb I'm not yet blessed with permission to post links so you'll have to go search for "electric Hefty-G"  Battery chat is in part 5


The tractor has been running great since this past spring and the estimated 7kWh capacity of the pack is more than adequate for our needs, not that that means anything to anyone but at least it means I didn't totally F#$% up on my initial guesses.  My use of the battery never really puts any strain on it because peak power demand is only 15kW (375A) and it never sees that for more than a handful of seconds (typical sustained draw is more like 5 to 7kW) and with 112 cells in parallel that's a paltry 3A peak with sustained values around 1A per cell.  So I don't have any good data on stress-testing these batteries but I can say that it is possible to build a totally functional low-speed EV around them provided that your energy density doesn't have to be top notch and you can spare the space for the not-very-compact air-cooled module assembly.


Module design and build quality seem exceptionally good but BAE is an arms dealer right, not just a hybrid bus huckster, so no big surprise there.  I've discarded their BMS as being too sophisticated, incomprehensible and proprietary and I've just built my own monitor-come-BMS type things for each pack.

Someone noted that there's no fusible link in the OEM build but I suspect that the narrow waist in the nickel sheet at one end of each cell provides just that.

I've also used chunks of the packs, as others have suggested to get 4S8P blocks (3 per module if they're all good) that can be used as 12-14V batteries.  In fact there's one of those as accessory battery on the tractor, charged from the main via DC-DC that does CC/CV.  It's overkill for lights and whistles but hey, I wanted to try it and I had lots of cadavers. Pics attached. 


So that worked okay but they're far from compact and you have to tear the module apart anyway so why not start stripping to individual cells?

To break down to cells I had good luck working simply with angle snips (sidecutters?) and working down the pack in zig-zag so that I was only working on one side of an 8P block and then the other side of same and then on to the next.  A sharp and slender pair of sidecutters can get under both sides of a spot-welded tab and break the welds pretty cleanly by closing the jaws to sever welds and meet.  I've only taken a few modules down to individual cells but it went pretty smoothly and my rate of 1 scratched can + wakeup spark per 100-odd cells is fine with me.  I can't remember which end but someone else noted in this thread that on one end the can is hot and very close to the terminal of opposite polarity so watch not to scratch the insulation, especially on that end.  Still, no fires or excitement of that nature.  They're small right, keep a door open nearby in case you need to toss one?   Confused

With the individual cells I've started building smaller, more compact packs without air gaps, mostly with an eye towards building a small ammo-can booster pack for diesel tractors and to power portable 12V loads like LED lighting or whatever.  So far I've only tried small ones and the Chinese spot welder I bought is crap and slowing my progress but it's still fun so far.  There's a pic of one of these 4S packs below, including a tiny 4S active balancer from China.  I 'm trying out these $10 balance boards as a cheap alternative to a full BMS and providing over/under voltage protection separately.


Attached is a great guide to using these A123 cylindrical cells with loads of info on pack desing and so forth.

And kudos to whatshisname (or her) for the pickup battery at the top of this thread.  So nice!

Also, I'm no expert but I agree with FrankZ that a lot of microcontroller-driven "smart" chargers for lead are following a CC/CV profile with 14.8V target and that these would probably work just fine for 4S LiFePO4 packs.  I was about to say that I'm not going to try it but then again I just might  Big Grin

thanks all, stimulating reading!
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#25
Do'ers are always welcome here, your thread elsewhere was a good read.

https://www.diyelectriccar.com/forums/sh...ight=Hefty
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#26
I have mixed feeling about the BAE-200 modules... I bought a few, and they were not as great as I hoped.  At least for the time / labor involved, I personally would look elsewhere unless you are getting them for next to nothing.  Buying from Alarmhookup / Batteryhookup was a mistake.

I see about 30%+ degradation and a lot of balance issues on 12v "chunks".  Tearing down the the cell level is just way too much work for what its worth.

If you can use them as-is, fully assembled without taking it all apart, that is perhaps the only way I would consider buying these things.
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