Monday, October 4, 2010

Fall Update

I've been busy with other projects but it is time for an update. My twike has set idle for the last 12 months while I sort out battery issues. The old NiCad cells from 1985 are pretty much shot but I have put together (after much testing) two packs with the best cells from the 5 packs I have. Unfortunately, while installing the packs into the car, I shorted out one of the NTC temperature wires on the mid pack fuse resulting in damage to the BMS board. The car will not charge without two (min) working BMS boards, so I'm down until I get that fixed. I finished my testing of A123 cells and found them of high quality and quite reasonable to work with. To make them work with the car will require me to design or purchase a factory BMS solution. To date, this is more $$ than I am willing to spend, so I'm exploring selling all my lithium batteries, buying replacement NiCad cells, and replacing the battery cells myself. The DeWALT LifePO4 packs are now up on (selling slowly) and I found a great deal on 3.6Ah SANYO C size NiCad cells (no longer made). I bought enough cells to replace 4 packs with the idea of doing my two packs and 2 packs for a fellow Twike owner in the USA. He agrees with me that the cost of the lithium upgrade when bought from Europe is just too expensive at this time (most of the cost is importing the cells). Next steps are to fix one of the broken BMS boards (or order a replacement from Germany for >$500USD), then begin the process of replacing all my old Panasonic 2.8Ah cells with the new SANYO 3.6Ah cells. I have friend who has a battery tab welder (makes his own A123 packs) who will rent me time and I just need to order some more Nickel tabs (only have 100) and thermistors, some shrink wrap for the cells, and it will be time to perfect the art of pack creation. I hope to have the packs refurbished by the end of the year (given time constrains).

1 comment:

Lex said...

sorry to hear you haven't been able to enjoy your twike. Mine is in storage while I get my house finished. I hope it never has these issues! I wouldn't know the first thing to do!