Yesterday, I was able to pull a block of cells from the Mitsubishi i-Miev battery pack.
The entire battery pack is comprised of 22 blocks of 4 lithium cells. (At first glance, it looked like they were blocks of 8 cells. It’s only after removing a 4-cell block that I realized they are all the same size, but in the main pack areas, a divider strip visually covers where they butt up.)
It looked like a bit of work to get any out of the “main sections” of the battery, but right in the middle, there were two smaller blocks of cells that looked a little more accessible. So, I set to work to pull one out. The one I chose was fairly straight-forward. It had a metal bracket holding it in place, a BMS wire connector plugged in, and bus-bars going to both ends of the cell block.
I removed the bracket, unplugged the BMS wires, and unscrewed the nuts holding the bus-bars to the terminals. With that done, I was able to remove the block and get a better look at it. It’s four cells, all held together by black plastic around and under the cells, and a black plastic cover. This essentially makes the four cells into a 12V battery.
I took the battery into my house to give it a bath. (I had already tested it with a volt-meter, where it BARELY registered anything higher than zero.)
One of the warnings on the battery included to NOT get it wet. Of course, that was a laundry list, which also mentioned not exposing to sunlight or feeding after midnight. The battery was covered with rusty, icky, red sludge, so into the bath it went!
I rinsed the battery off as best I could under the faucet and showerhead (wearing safety glasses and rubber gloves) and then popped off the the top cover. Under that was the BMS board, screwed right down to the cell terminals, and rusted and corroded like no tomorrow. I scrubbed that down with an old tooth-brush and also removed the bus-bars that connected the individual cells.
Overall, the entire thing looked very corroded. The terminal lugs and nuts are stainless steel, so those were actually in good condition other than the corrosion that was on them (but could get cleaned off.)
It seems to me that the BMS boards are completely shot, but it might be possible to remove those and then individually test the cells. If there ARE any good cells, possibly some of those could be rebuilt into a battery pack for an electric bicycle or similar project.
In the mean time, I’m not holding my breath to expect that I’ll ever be able to drive this i-Miev again. It appears that the electronics overall are completely ruined. (Although the body and interior are in perfect condition and the driveline in likely fine.)
I’m hoping to take this cell block over to a friend’s house where we can test it and see if it will take any sort of charge.
Here’s some photos for you to enjoy of dissecting this battery pack!