Hello everyone, I have a possway T3 that is coming up on a year old now. It has worked great and I have over 1200 miles on it. Recently I took it for a ride to get to campus and didn’t think the roads were as wet as they were. I dried it well and stopped riding after 2 miles, and when I got home it seemed fine. It ran for 2 more days then wouldn’t charge. The charging brick started flashing red and staying red with nothing plugged in(it should be solid red when charging and green when nothing is plugged in).
Anyways disassembled the board and found water had been trapped by the battery’s plug, I cleaned it and dried it over a fan for a day and then it started charging and ran great last night. It got about its max range and wasn’t even dead so I figured all was good. However it started not charging again with the same charger flash. I’ve checked the charger is outputting the full 42V even with the red flashing. And the board is holding 36.7V (it’s usually between 36-42V). The board runs still and everything works, but it won’t charge. I find it weird it charged last night, but won’t now, I wonder if the BMS is damaged? Could I just bypass the BMS and use the board as is without it? Any other idea as to what might be wrong?
Buy a new battery. It’s not what you want to hear, but if it’s not charging, there’s a reason. Bypassing the protection that is there for a reason is a fire waiting to happen.
If you want a more formal diagnosis of what’s wrong with your board, giving a location would be helpful in case there’s someone knowledgeable nearby that can assist
Ok so I took the advice to open the battery and let me say that case was very annoying. But I did not unwrap the cells. The BMS was very small and looked like the side going to the battery had been fried, probably from water. I cut the BMS off and hardwired the port to the battery and it’s charging fine now. The charger isn’t flashing red (but won’t go green with nothing plugged in), but the boards gaining voltage. I think my plan will be to just use a mechanical timer to charge it for 3 hours from almost dead to make sure I don’t over charge it. And of course never ride it to dead. Is there anything else to be concerned about with no BMS?
A bms is needed to keep each p-group balanced. Charging without one can and will lead to imbalances between cells and quite possibly a fire. Maybe not now but eventually.
You cut the bms out? Meaning you left all the balance wires loose where they could possibly short? Also, did you solder the the charge port to the positive or is it some kind of a loose connection?
I’d definitely tape off any exposed ends and take it to a recycling center. The battery knowledge you need + tools to fix this isn’t going to be something you can learn quickly. Or maybe see if there’s a local builder willing to help you out.
Your bms doesn’t tell the charger when to stop per say, it just makes sure each p-group is at the same voltage. Your charger should stop charging on its own once the battery voltage reaches 100%. Without a bms, one p-group could end up above 4.2volts while another one is under 4.2volts once fully charged. See how this is might lead to a fire? If it’s a 12s battery, a bms would keep it so each group is at 4.2v fully charged. Without one it could be 4.1+4.3+4.0+4.4+4.2+4.2+4.3+4.1+4.2+4.3+4.1+4.2=50.4volts
Well thank you all for the knowledge the battery is unplugged and outside… looks like I’ll be looking for a new battery. As far as this one goes the battery had one red wire to a small BMS then a red wire off the BMS to the charging port, also a black wire from the port to the battery. Is this comparable to other standard BMS’s, could this battery be fixed by soldering on a new BMS or is it just trash?
Well good to know thank you. I’ve done plenty of soldering and plugs and lights, but never really messed with battery’s. I’ll get it to the waste center tomorrow it’s outside away from everything for now.
The battery might be ok and just the bms dead. Was the battery sealed from water? I wouldn’t do anything till you see if water got in and if all the p-groups are the same voltage.
I wouldn’t ride it without a bms regardless and u could get another if the battery is ok
