Sunday, January 3, 2010

Jan 2010 update, part 2

More battery pack construction. Here I am balancing groups of 8 cells. I'm connecting 5 eight group cells in parallel so it results in groups of 8s5p. I'm using the Chargery DB8 balancer and a lab power supply to charge the cells. Only takes a few minutes to achieve a full balance as these cells are brand new. I'll do some full charge/discharge curves on each group of cells before putting them into the pack to identify any cell defects upfront. I'll have more pictures and descriptions as I get further along on the pack construction. I can not tell you how careful you have to be with metal around these very powerful cells. I remove my wedding ring when I work and have a fire extinguisher handy to deal with any meltdowns. Also, note I place the cells into a fire safe container even though it should not be possible to get these cells to burn (safe LiFePO4). Also, I've got 70 8 cell Dewalt DC9280 tool packs to harvest cells from so it will take a while.

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