Lifepo battery problems

[Bluenose]

I'm having some issues with my new lifepo battery, it is 36 volt 10ah, I can't seem to keep the cells balanced after charging, the motor cuts out after only about 3 miles, I can;t tell if it is a defective BMS on the battery or a bad controller. How can I tell? Can the battery be used without the BMS, like a regular old SLA. I know that lifepo is all the rage right now, but my trusting old 24 volt SLA battery in my IZip looks pretty good.

HELP! - I'm about to throw in the towel and dump a real cheap lifepo on market soon.

[Patriot]

It does almost sound like you may have a bad cell in there somewhere, and it's dragging the rest down. This could end up bad.

Do you have any way of deep cycling and checking each cell? Or is it a sealed up inaccessible block of cells?

[Bluenose]

I checked and balanced each cell with a single cell charger that came with the battery. I'm going to leave it now on the main charger for 24 hrs. to see if it balances the battery, but my suspicion is I got a bad controller from Golden motors. If the battery stills shows 39 volts and the motor is cutting out, shouldn't the controller be alright down to 29 volts for a 36 volt controller? But I can't rule out the BMS either, I'm waiting to hear back from SAM at Yesa to get his opinion.

[Patriot]

Yes, that would make sense.

The only other thing I could think of, is if there is a short somewhere which is tripping off the motor. Or, like you said, the controller itself is bad.

This is why I'm planning on getting one of those neato Cycle-Analyst doo-hickies. They read just about everything important to let you know exactly what's going on.

[crackerdog]

If you disconnect the battery and then reconnect it, does it work again for a while?

[rtz549]

Might ask on here: http://evdl.org/

[Bluenose]

I got a message back from SAM at Yesa with some ideas, sounds to him like I have 4 unbalanced cells, that will need some coaxing and individual charging for a few cycles, but he says the battery will eventually start balancing properly, if I had the money to do this again I would just go and get the Bionx set-up and be done with it - this is too much fiddling around for my liking, but I guess that's what happens when you are an early adopter. I would disconnect the battery connect it again and the cut-outs would still happen, I think the BMS is shutting down the battery when it detects if one or more cells is off by too much. I had one cell go down to 2.5 volts - is this bad?

[Bluenose]

I just want everyone to know that although I'm having some issues with a new battery, Sam at Yesa has been great - he answers all my emails, his customer service is awesome and I know he sells a good product and I'm sure he will work with me until I have it all fixed, I realize that sometimes these things can happen with a new technology, and I'm learning things about batterys I thought I would never need to know. Others have used these lifepo batteries with no problems. I'm using it with a golden motor kit, and when it does work, it is very nice compared to the 24 volt Izip from CT I have, it is absolutely quiet and after I changed the tire, tube and tightened the spokes the front wheel is nice and solid, I'm pretty sure the problem now is with the unbalanced cells tripping the BMS early and not the golden motor controller, further testing and charge cycles will hopefully solve the problem.