Cellman A123 battery help.

B

bustedknuckles

10 mW
Joined
May 27, 2012
Messages
28
Location
Portland OR.
Hey everyone,
I've been running an A123 51v 20a set up, that I got from cellman, for a few months. Its split up in to two blocks so I can fit it in my panniers with anderson power poles connecting the blocks. About a month ago one of the Anderson's melted bad enough that the connection was lost and the bike shut down.
After I replaced the melted Anderson with a crimped butt connector everything worked mostly fine except I've been noticing a greater voltage sag lately. Then, the other day, I experienced the same loss of power as when the Anderson melted so I got the bike to my shop, charged the batt and prepped the batt wires for some new 45a Anderson's. While I had the batty split I tested the blocks individually and got 29v on one block and 20v on the other. This was directly after a charge and my CA. said the battery was at 59v. So today I checked each block and got 26v and 0v respectively.
This battery is pretty new, I've only drawn something like 370AH out of it total. I see two problems, I'm drawing too much power between the blocks for the anderson connectors and somthing's wrong with the one block. Any ideas what's going on here? Did I ruin my battery? Or did I just get a bad set of cells?

Thanks all.
 
Hey ypedal,
I'll get some pics later tonight. The length between the packs is a little over two feet, I think 8ga but I never asked cellman, he said it'll work, it's about 3/16in thick. Tested it at the charge cable and the connection between the blocks. The block that's bad is the one that houses the BMS. I haven't opened the packs yet to test the cells, that's next but I was hoping to avoid it.
 
I tried getting ahold of Paul but it seems this is his busy season. I don't know what his warranty is, I don't want to open this pack untill I talk to him. On the other hand, this bike is my only transportation and I may not be able to wait on him. I'll give him untill Saturday, which is my next opportunity to get any work done on this batt, and then I'll just go ahead and see what's going on with these cells. Thanks for the help.
 
i bet you ruined the BMS when you burned up the connection. that has to be soldered solid and never opened when the BMS is attached. you are draining down the cell above the break because the shunt transistor is shorted. you need to put the battery on the charger and list the cell voltages here, but i know the BMS is ruined. that cell is ruined too.
 
Well, I emailed Paul two days ago and he hasn't gotten back to me yet. It looks like im going to have to open this pack up. Kind'a disappointed, I bought one of cellman's batterys because I didn't really want to have to mess around. If I wanted to screw with a battery pack I would have built my own. Not to imply Paul's a bad guy or anything, He's been great to work with so far.
Dnmun, how do I chech the BMS to find if it's ruined? Oh, and wouldn't the LVC shut everything down once the connection between the packs was broken? Wouldn't that save the BMS?
 
I think they have a two day May holiday for workers. Anderson are junk for that you need some 5mm gold bullets. Anderson's melted on my phase wires when the wires were too long. They work on my shorten wires.
 
O.k start with the total output then follow down backwards. 51v to 25v. then cell voltage. you can first check thru the bms plug if your voltmeter is pointed. I ground mine down to a smaller point for access with a HF cheap daimond blade. This is so you don't cut it open. Do tell us what Paul tells you.
Do wright it down the cell volage as it's the only way
1. 3.33v
2. 3.43v
3. ????


16. ----v.
 
Thanks for all the input guys. I'll be getting in to it tomorrow evening. I got a new multimeter arriving tomorrow, I dont trust my old one for this kind of work. I'll post some pics and the individual voltages. Paul is still MIA.
 
So Paul just got back to me, here's his email.

"There is a BMS fitted in 1 of the packs I am sure and if that is not fully terminated it will protect the battery and you will not see the correct voltage when you measure. It can't be fully terminated unless it is linked together with the other half of the pack. I doubt there is a problem"

This was before I got a reading of 0V on the one pack. I previously got a read of 20V on one pack and 29V on the other, so this is what he's replying to.
I emailed him back and let him know what the case is currently.
 
Check to see if you need a new pos. or ned. wire and /or connector's and go direct to pack for voltage to check first if this is needed. That's if you want.
 
Paul got back to me this morning. He says there's probably nothing wrong with the pack, to wire it back up with some bullet connectors and it should work fine. He says the low (no) voltage I'm getting is just the BMS doing its job and im not checking voltage at the correct point. I'll let you guys know what happens.
 
Yes I sounds like a broken connection at one point. Not seeing the pack I don't know how much access you have to the battery without cutting it open. If only you could get to the pos. and neg. on the battery itself.
 
Where does paul put the bms is it inside the wrapped pack ? Or sealed up some way. I think he's opppsed to cutting. The wire at the other end of the anderson is shorted. Yes my guess.
 
Yeah, I think the BMS is under a piece of fiber board, wrapped in heat shrink, at the top of the pack. It wouldn't be to hard to get to.
I hooked everything back up yesterday using some 75A Anderson's I had around, the voltage was good but I'm still getting a low v shut down after a couple minutes of operating the motor. I'm guessing I have a loose connection at the batt ends of the connecting wire, at one pack or the other. Ill probably have to open the packs up to check those connections but I'm waiting to hear back from Paul. He's great with support but he's so busy it takes him a few days to reply so a conversation takes weeks!
I have a loop of about 3/4 of a mile that I've been riding to test the bike on and it cuts out at the exact same point in the loop every time. The volts will be reading 49.9 and then just cut out the next second.

Another thing that I've been noticing is the Anderson's that connect the batt to the controller have been getting hot, not hot enough to melt but quite warm, I believe they're 45a. I adjusted the Anderson contacts for a tighter fit but I'm wondering if a loose connection here could be the culperit. The CA has a low v cutoff at 10v.
 
the only place I put anderson's is on the phase wires. Yes I have melted them there in the past. And would put 4mm H. K. gold bullets there next time. But with a battery it would be 4mm or better of H.K. not the bullets they use on the trailer's or withe the cheap ebikes.
 
I finally got around to working on this pack but after pulling them out of my panniers ( where they're Velcro strapped to the frame panel) and there's two puffy cells in one pack. These have puffed up to around 4x thickness or more. Could these be the reason for my low v cutout or is this just another unrelated problem?

Yeah zip, I am coming to the conclusion that Anderson's aren't the best option, I'm going with all bulett connectors now, once I get this battery back in action.
 
Thanks for your input dnmun. I'm not "refusing" to do anything. If Paul accidentaly sent me some bad cells it's a warrantee issue in my opinion and I'd rather be able to send these packs back to him in as few pieces as possible.
I'm not really asking for incendiary comments, I'm more interested in advice, recomendations, and education.
I'm trying to take this process slowly and am posting my findings step by step. Puffed up cells seemed like a big deal to me and I wanted to see what the community thought about this new issue.
 
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