The basic CBAII is fed by a pair of 12AWG silicone leads connected to the cell via Anderson Powerpole connectors. The amplifier requires connecting the cells to its 5/16 inch terminal bolts. We decided to wire the cell to the amplifier with 10AWG wires - two per pole - with crimp-on ring terminals. It's giving us very low resistance connections and should give us an open highway for electrons to flow from the test cell.
(Click the image for a readable chart.)The first round of tests took us from 10A thru 40A (4C) in 5A steps. This chart covers discharge cycles 23 thru 31. 25 and 28 were aborted due to improper setup of the monitoring software. (The boss forgot to enable the amplifier at test start. He's exiled to his office until we test at 10C.)
Test environment is a 24º-25ºC (about 77ºF) air conditioned lab. A couple of the tests were conducted on a quick-turn from the chargers - we didn't let the cell sit to cool and stabilize. Starting cell temperature ranged from 25º to 27ºC. End of discharge temperatures from 20A to 40A ranged from 34º to 42ºC (93º to 108ºF). We're finally starting to see a bit of heat on discharge. There's no significant heating on a 10A charge (1º-2ºC above ambient) - same for discharge up to 15A. Max discharge heating noted so far is 17ºC.
Capacity is trending slightly lower as discharge rate increases. We're down to 9.91Ah at the 40A rate. We've noticed a slight variation in the cutoff setting for the Voltphreak 2A chargers and we expect this will intruduce some cell capacity variation. Overall, though, we're happy with the consistency of the data so far.
Stay tuned for the next installment - maybe we'll hit 10C and let the boss out of the office.
Posts
