The Rezistor - LiFePO4 pack status

jstept's picture

I took my damaged pack over to Synkromotive today to have some experts take a look at it. We took voltage readings of each of the 12 cells. They each read about 3.3V, except for two cells. One of them read just about zero, and the one with the obvious damage read about 1.8V. Their advice was to just replace the bad cells and keep going. They also briefly studied the BMS that came with the batteries, and deemed it satisfactory.

So now I just need to email Sam at Yesa and get a couple new 20Ah cells, install them, then replace the charger wires with the melted insulation, and I should be good to go. After I build an insulating case for the battery pack....

Can anyone recommend anyplace that recycles lithium?


before comments


Rogresalor's picture

That is not funny. You aspect a good working batterypack with a BMS installed and how could it occur the cells reaches zero volt? Though it is nog 0 volt, but I think the BMS traps in because these cells became under the critcal level.

Yes, you can easeally replace the bad cells for good ones and I've contact too with Sam from Yesa and have made an offerte. (a small world ;) )
In my situation SLA is over 3 times cheaper than a total LiFePo4 sullution for my scooter and afer 20.000 km this scooter is replaced by another. If I consider LiFePo4 batteries I must be sure the scooter have a long lasting life and I should bought it here for warranty. Over 2 years I want another scooter and then I opting surely for LiFePo4.
LiFePo4 is much better than SLA in any way! but I only put them in a brand new scooter. Also my scooter is 60 volt so I've to buy 2 additional packs with 2 chargers and at work I can charge it, but one plug is available at office.
The route home-office is 13.5 km and the route home-main office is 21 km.
If I went to the main office and then the meter dives deep in the red zone, it is not good. Also my pack don' t like heat above 20 degrees celsius. At 35 degrees it perfoms very, very bad so it is almost depleted and next week I've new ones.
I've ordered 5 new SLA for the scooter and then I can ride at least 8.000 km without the fear for malfunction for warranty purposes only in mind. I'll buy a seperate 12 volt SLA charger to charge each accu seperately once a month to top them off. A serial sollution is not nice for SLA. I don't know if this is for Yesa's batteries too?
But, how could it happen these cells went wrong and became defective? These "zero volt cells" aren't recoverable.
I'm just curious about that.

Maybe you don't like SLA, but it is the accu where I've al knowledge about it.
At first I pay the 5 SLA's I ordered. They deliver them next week here at home. I top off each battery (a battery is in my eyes one module of 12v) each month.
I guess my setup is know out of balance, but not usual after a nice 6400 km driving. In the beginning I abuse the batteries by exploring range and this time I don't do this again. SLA don't like deep discharging. My error in the beginning days of EV driving. Now I'll pay that bill. Luckely I can pay it :)

But, still I like electric driving and I continuing it. If I pay 267,75 euro inclusive al tax and delivery at home, that is not expensive for 8.000 km. This time I maintain the pack better.

I'll wish you all good luck with warranty and a nice driving ;)
Mostly LiFePo4 won't fail eseally.

But I first top off each old battery to see what I can do yet. I'll store the new ones for a little time at topped off state to deplete my old pack first to the critical level of 21 km coverage. Saving money until the last cent.

Jeffkay's picture

Don't forget to make the pack's existing cells and the new cells match volts under load fairly close before wiring them in. I know your BMS should take it from there...
Jeff K. "Deep Cycle"
P.S. Thanks for your fire! I plan to beef up my rubbing parts, if you know what I mean.

dogman's picture

A good bms should equalize the cells in the first few charges, my ping did a lot of that at first, and now it just charges and shuts off. But if my pack was allready torn apart, i would definitely charge each cell indivdually before i put it back together. I'm so jealous of your resistor, old farts like me love retro.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

jstept's picture


Thank you for your kind wishes. The cells did not fail because they were faulty or because the BMS was faulty. I made this clear in my earlier blog post. The cells were damaged because I did not secure the packs adequately and a corner of one of the casings wore through, creaing arcs to the body frame.

I have been pleased with the performance of the Yesa LiFePO4 batteries thus far. Yesa's BMS also seems to be functioning appropriately. I strongly recommend that, if you buy a Yesa battery pack, you build a tough, insulating pack for it and secure it so it doesn't move around in the vehicle.

Good luck!


2020 Hyundai Kona Electric
Apollo City

dogman's picture

I understand, and just did some better protection for my ping, mostly as a result of reading your excellent posts. I just meant that it would be an opportunity for you to do the kind of dialing in the battery that the better e bike shops are doing before they will sell em. My ping bms did actually seem to be doing something to balance the battery, but untill I have a reason to tear mine apart I don't really know if it is or isn't. Since I don't understand the wiring from the pack to the bms I'm hesitant to poke around with a voltmeter. Still envious of the Resistor!

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

Rogresalor's picture

Ok, I understand the problem and that is my kind of fear to buy a LiFePo4 sollution and something went wrong.
At first I should find a local retailer and not one out of America. Is one cell fails; warranty.

@Dogman; maybe in the last post ago you understand me wrong. Nothing intended, but here in Holland is a LiFePo4 sollution very expensive and even if you should correct, though they're expensive too.
If I liv in the united states than I have another speak ofcourse ;) Your electra is 4 times cheaper per kWh than here and LiFePo4 is 50-130% cheaper than overhere.

Where you look, especially in Amsterdam and you visit every electric EV retailer, you got SLA in your vehicle. Why. In our land SLA is the most cheap and reliable sollution, but why al this complain?
People don't maintain their batteries well and that's their fault, not that of the SLA.

But to be honest. The prices of LiFePo4 decreases slightly here, so, next year I buy LiFePo4 instead.

I hope I'm clear, my English is not that perfect, sorry in advance

dogman's picture

I am also sorry if we got off to a bad start. I think one thing is that we tend to travel longer distances here in the USA. Out west where I live, almost all ev's are impractical since 250 miles is considered nearby. Lifepo4 range really makes the difference for a lot of us. You see a lot of newcomer posts that ask, how do I build an E bike for $1000 to commute 60 miles a day. You don't, but maybe you can for $2000. Lead batteries are cheapest. I wish I could use those batteries in everything. Another poster on endless sphere is claiming 1000 miles on his ping lifepo4, so I hope for mine to be ok.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

If I were in their place I wouldn't have adviced you to do that.


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