Raleigh stow e way bms issues

[Torqu-E-Cycles]

Has anyone repaired the bms in a Raleigh stow e way battery? Its not a typical diy style buy off ebay type.

Battery had out of balance cells, rebuilt with new LG cells as per original, battery worked for few seconds then shut off, cells started to go out of balance and after 2 days the first 4 series are completely different to the rest, bms must be balancing incorrectly as they are brand new from cell supply, built tons of batteries with zero issues.

 

[docw009]

Looks like a well build battery, but the author of this video said LH MJ1's are too small for a 10s-2P that has to pull any load,. Maybe, but they should last more than a few seconds.

Not pulling high current? No broken/bad welds making some groups 1P? Did battery hit full 42.0 volts on recharge?

He made us watch the whole sequence while he pulled the battery apart.

 

[Torqu-E-Cycles]

No the battery charged for around 30 mins, turned on the bike for about 5 mins. Never rode it just turned on to test.
The battery came to me with cells out of balance so I replaced them with cells all at 3.45v, it charged to around 3.75v but now the first S is 3.64, 2nd S is 3.83, 3rd and 4th are 3.61 and the 6th to 10th are 3.73.

One would assume that the bms has a balancing fault and is scavenging from the out of balance ones, question is, is it likely to be the balance chip or the loads of transistors and diodes in front of the balance plug!

I have recelled loads of these same batteries and all have worked fine for years, I run an ebike battery repair shop so its a very common job but never seen one with a balancing fault on the bms before, normally the bms just die.

 

[docw009]

You charged from 34.5V to 37.5V and all seemed well, but the bike shut off. Was it the controller shutting down or did the battery BMS pull the chain?

When you check the balance voltages, you got 3.64,3.83, 3.61, 3.61 and the remaining six are all 3,.75. None of those are close to the 3.0V that triggers a BMS shutdown. Well, you must have plenty of spares. Try another BMS.

My BMS understanding may be wrong, but if they balance, that won't start til a cell gets near max voltage. Otherwise, the BMS stays out of the way while the cells charge, but it will shut off the battery if any cell is under minimum voltage and either stop charge or start balance when a cell hits max voltage.

Did you check that all 20 cells were at 3.45V when you started? I recently odered some new 21700 cells amd one came in at 3.26V and the rest at 3.45V. Being suspicious, I did a capacity check and it was only 3AH. Bummer. Now I have to check the other 29 cells. Gone thru 12 and those are all above 5AH. Taks a day to check four cells, so I'll be running capacity testing til next week.

 

[Torqu-E-Cycles]

Sadly I don't have a spare the same or I'd just swap it, the bike won't power up with a bench supply so it must want to see something else from the battery, probably can bus im guessing.

All cells were exactly the same when built, nothing wrong there. The bms shut down charging and currently won't turn on the bike. Headache!