A123 20AHr Pouch Cell Battery Build & Info Thread

[999zip999]

I think signalab cutoff is a little higher 3.8v. then headway bms. Plus ypu can solder up the shunt a little for higher amps. Do you get the 10 fet signalab ?

[999zip999]

Pack built using JD's roll the cotter key then use a alunium or brass tube with a slot on the bottom to slide, then crimp over the roll. ? Finish with JD's shrink tube style.

[toolman2]

Yeah, this is just an idea, but If it works well I would get 50 boards made up. Getting the brass blocks cut, drilled and tapped would cost a fortune, but they should last forever (and be re-useable).

I admit I was inspired by Agniusm's A123 boards, but his works perfectly for 1P. For motorbikes or cars, you will need at least 2P, which is what I have in mind for the eCRX project. You can also get 4P boards made up if you are going for a low voltage DC setup (144 V or so). But I imagine EiG cells for e-bikes would need a more compact system, and I reckon Agniusm's is pretty good for that.

you could use 1000 series aluminum, i think its twice as conductive as most of the stronger alloys, you often get it as a cheap grade from say bunnings.

[jonescg]

I was thinking of going with brass because it solders easily. The solder is really just there to keep the block from moving when you fold the tabs over and tighten down. The other benefit of brass is I have chosen 6.3 mm square brass bar (standard size) so no additional machining is needed - just drilling and tapping. I have improved the design of the PCB a bit too so that I have room for two 7-pin JSTs and a 6 pin JST (19s all up). So the blocks will need to be able to conduct reasonably well.



Anyway, the cells cost a fortune, so I don't think it will matter right now

Edit: Added top secret PCB design which is going to earn me billions

[ohzee]

I think signalab cutoff is a little higher 3.8v. then headway bms. Plus ypu can solder up the shunt a little for higher amps. Do you get the 10 fet signalab ?

not sure who you were asking , but I just counted the fet's on my signalab and it has 2 rows of 6 so 12 total.

I am very happy with it so far.

[999zip999]

Ohzee I was looking for the 16s 10fet signalab in the garage, can't find it. Your signalab 12 fet is for how many serials and how many amps. With those pretty leds ? I would buy one just for those led's

[jonescg]

Just got a quote for the brass blocks, drilled and tapped. For one 19s2p board you would need $320 worth of machined brass (assuming 40 pcs, 6.35 mm square). Copper would cost about another $60, provided I did the drilling myself. PCB might come to about $15 each... hmm so something close to about $400 per 2.7 kWh pack. Adds about 13% to the cost of the pack maybe? Have to check what their termination system adds up to. But then, where's the fun in that eh?

[ohzee]

Ohzee I was looking for the 16s 10fet signalab in the garage, can't find it. Your signalab 12 fet is for how many serials and how many amps. With those pretty leds ? I would buy one just for those led's

I just looked up my old email from ping.. he called it a high rate BMS - it's 20S 94+20$ shipping.

Ill email him and ask what the amps are.. I thought it was 50amps.. I have pulled 40 with no problems.

i agree the led's are pretty much kickbutt.. the BMS works great at keeping the cells balanced..

ping responded 60 amps on his high rate BMS 20S

jonescg that looks pretty awesome love to see the final product.

[docnjoj]

It is a shame 20AH A123 cells wont fit. Darn!
otherDoc

[jonescg]

It is a shame 20AH A123 cells wont fit. Darn!
otherDoc

That's OK man, it doesn't exist yet You can easily get one of these made up for A123s, but I don't know of too many folks looking to run ebikes with 40 Ah worth of storage!
I doubt you could get a 1P setup to work here because of the tight spacing.

[voicecoils]

If anyone wants to throw down some termination suggestions for a 24S2P stack, I'm all ears?
Cells purchased and just received - planning to load it into a pretty light & short range motorcycle build.

Peak current will be 450A max, so 225A per cell or 11C, they'll just be getting tickled.

I'm thinking super thin double sided tape between cells, kapton tape around/between tabs.

[jonescg]

I reckon you could modify the dimensions of the PCB I have posted above and use that as a template? Would you even need to tape between the cells?

[voicecoils]

I reckon you could modify the dimensions of the PCB I have posted above and use that as a template? Would you even need to tape between the cells?

Thanks, that may help. Not sure if I want to go the PCB route yet for a 1-off pack.

I have some extremely thin 3m double-sided tape, maybe 0.2mm and I was thinking it could help ensure none of the cells move relative to each other and wear pouch material.

Kapton tape , just around and between terminations to keep things isolated.

Here's my little stash of battery pr0n, sitting 36cm high in a single stack:

photo 1 (5).JPG (98.72 KiB) Viewed 248 times

photo 2.JPG (105.98 KiB) Viewed 261 times

photo 3.JPG (109.27 KiB) Viewed 261 times

[999zip999]

You could have put a book on top and charged them all at the same time. Balance charge.

[ambroseliao]

Here's my little stash of battery pr0n, sitting 36cm high in a single stack:

photo 1 (5).JPG

That top one looks a bit warped. You might want to put that near the bottom of the stack to help flatten it out!

[999zip999]

Drutledge and Ohzee how are your packs working out and what is the max amp draw ? Any problems ? And what would you do different in that build. I'm going to follow in your foot steps two 12s for a 12s40ah or a 24s20ah flexable. 40 amp max draw.

[ohzee]

Yesterday I finally drained my pack.. It's a 20s1p. I tried to not pedal as much as I usually do so I could empty it out as it was quite a feat.
I did 29 miles and used up 17ah out of my pack. I have the signalab BMS high rate which max's at 60 amps and I used it on my yuba mundo mid
drive kit so an 8t . I have the CA limit to 30 amps so I don't burn up the motor.

Once home I sat down with the battery and tested all the cells to see where they were.. I had one cell near the middle of my pack which was
noticeably lower then the others. I may look into replacing and will be glad I covered my battery with plastic wrap before any tape.

I am very happy with this battery , but my amp draw is quite low.

[oatnet]

and used up 17ah out of my pack.
I had one cell near the middle of my pack which was noticeably lower then the others.
glad I covered my battery with plastic wrap before any tape.

At 30a/1.5c, I bet sag was minimal, a great quality of these cells.
I use a standard 80%DOD on these cells, so I would have stopped the test at 16ah - at 17ah you are into the knee of the discharge curve. What were the voltages of the good cells vs inferior cell at the end of discharge? Did you confirm voltages on the cells before your test, to make sure the BMS had accurately balanced them?
I use quality blue painters tape for the same reason you used plastic wrap - lasts for years, comes off in seconds.

-JD

[ohzee]

The low one was 2.62. The others were 3.04, 2.94, 2.95 all in that area. This is at rest.

I did test my battery previously when all charged and each time the BMS had them where I thought they should be
3.5x to 3.6x.

I do love these cells. They are turning out to be everything I thought they would be and I agree about stopping where
I did. I honestly just wanted to verify the BMS cut off power

There's nothing better then plugging in the charger in my garage and trusting it to turn off when it should.

[999zip999]

It conducts thru the aliumium bar as a buss.

[jonescg]

Hi Guys,
I wrote to EIG asking about some sampler cells and tab dimensions and stuff. They said sure, sign this mutual non-disclosure agreement...

I went ahead with it, cause I really want to play with these cells. But since I don't want lawyers getting all gloryhole on my ass (thanks for the image, Philistine ) I probably won't be sharing their information. I'll happily share mine though. What was I saying about gloryholes?

[999zip999]

Would it be better to connect the taps direct to each other with a alum-oxy paste, then use the aluimun as a buss bar. It does make a handy sense wire(s) connection point. I guess I'm asking what rate of discharge in amps can a battery made druledge method can handle ? 100amp ? With 12s.

[jonescg]

Not quite sure what you mean Zip. You mean doing away with the copper bars?

[999zip999]

I'm talking about the Drutledge pack build and he has the tabs on each side of the 1/4 in. alumiun bar. In a 1p build wouldn't it be better to connect the taps togethere with alium-oxy for a better contact. Or would it matter as with a alumium buss bar in the center as i'm only drawing 60amps. How many amps can be drawn thru this pack build on a 12s ? I just going to follow his foot steps as it has a good place for sense wires and end termanals.

[999zip999]

Sorry Jonescg There is 4 builds going on in this thread from Jd's to Drutledge's and a few tab connect's. I like it kiss and to be able to repalce a low cell as they did come out the back door.