lauantai 17. elokuuta 2013

Taking apart

Yesterday I proceeded to take apart the battery pack of the kWsaki motorcycle. I'll need the cells for my initial build of the kWsara electric car. I'll see if I can get more batteries later for the car and/or the motorcycle. Of course if I can't get the car to pass MOT then I won't have to.

In any case I thought it would be a good idea to empty the pack before dismantling it. This way it would have the least power stored in case I mess something up in the process. It turned out to be a little challenging and I couldn't avoid letting some sparks fly, so I guess I was on the right track. The minus cable of the pack had slipped into contact with the positive end of the 12 V lead acid battery. A little slip of a wrench into the chassis of the matorcycle resulted in some fireworks along with the bolt in the end of the minus cable welding into the battery terminal.

So yeah, let's be careful out there. Other than that there were no mishaps. I had pushed the pack down to 50 volts, about 2 volts per cell, but it had bounced back to 74 volts by the time of disassembly. All but two cells were at 2.95-3.00 volts. The remaining two were at 2.71 and 2.80 volts. Not sure why, but I may have sucked them a little bit more empty while bottom balancing, they may have been worse cells, I may have hurt them by sucking them too low or maybe some of the sparks I've made have caused them to get a little bit more empty. The difference isn't very big though, since the voltage drops very quickly below three volts. All in all I'm not worried and will just add some more juice into those two cells or suck the others a bit lower.

The cells aren't very clean due to my open design of the battery box and the fact that the braces had rusted rubbing some of that rust into the cells. The cells whoever seemed quite uninterested in their external appearance. Perhaps a more close box would be in order though. The next incarnation of the battery pack will be different anyway, so I'll see what I can do. That's for next summer in any case. I took the bike off insurance for this season.

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