Replace Cells?

[fechter]

I could see the pictures OK. Removing and replacing the nickel strips doesn't look too bad, but there is no way to remove cells without cutting away part of the cell holders or completely un-welding the entire pack.

To replace a cell group, I would pull the nickel strips off both sides of the bad cells, cut or break the tabs that prevent the cells from sliding out of the holder and then slide the bad cells out (might need a hammer). Replace cells and use a spot welder to place new nickel strips on the pack and maybe a little glue to keep the cells stuck into the holders.

If you don't have access to a spot welder, it is possible to solder wires to the cells, but that has some risk involved.

 

[999zip999]

Where is the low group of parallel cells located in the pack. Do check to see if that bleed circuit is self discharging on that channel of the bms while the pack is still togethere.

 

[pollywaffle]

Where is the low group of parallel cells located in the pack. Do check to see if that bleed circuit is self discharging on that channel of the bms while the pack is still togethere.

The first group

 

[999zip999]

On the negative side or the positive side usually the positive in goes out first. If overly hard discharge. Anyway and end group makes it a much easier for you to replace.

 

[pollywaffle]

Negative side. The entire bike was submerged in two foot of muddy water for about a minute or two. I was knocked out/dazed for thirty seconds or so and up to my knees in mud against a six foot vertical wall of the drain. As i tried to drag the bike out by the rear wheel, the throttle kept getting activated, dragging me back into the water. I dried the battery in the sun for half a day but I didn’t know these batteries are not water proofed at all. I pulled the battery apart three days later and there was still a little water in the end cells. The BMS was damaged but I didn’t initially know so i was trying the run the bike with a wet battery that had a damaged BMS. I think this combination is what damaged te cells and i am probably lucky that only one cell group has been damaged.

 

[fechter]

I agree with your assessment. Sucks to have an expensive battery damaged.

Your options are DIY repair with no guarantee of success or replace the pack. Cells that get damaged in that manner may be more prone to catching on fire later. Always charge in a fire safe location.

 

[pollywaffle]

It was an expensive lesson but a lesson nonetheless. I also destroyed my $1500 iPhone but it could have been much worse. I am impressed with how robust my bbshd is after all this.

 

[larsb]

That's quite a crash. I'd actually retire the whole pack after such an incident. It's not a high quality pack to begin with, it's got nickel plated steel tabs (now rusted) and little series connections. Water can have entered into the battery tops. Etc.. It's not without risk to keep it and you could get more cells that get issues in a short time..

 

[pollywaffle]

Wise words. It had a high quality price tag tho unfortunately

I bought another battery the day after the incident anyway and have been using it since