Fri 20 Feb 2009
This past Tuesday the truck got another deep discharge on the nicad pack. The range was low, but it had also been cold lately. The pack went from -4kwh to +5.3kwh or -17ah to +29ah. This is encouraging. On the 5.7 mile drive to work, the pack voltage never went below 310 volts. This is also a good sign.
I’ve also been working hard on an analog Lithium BMS for 160ah cells. Later, it will be adapted to 40-90ah cells. The board has been iterated a couple of times. Each time better ideas were added for the layout. This last version needs to be built yet as it had some serious changes. The first version is built on a breadboard and works fine.
This deep discharge should be done at least one more time. The nicad manual states that sometimes up to 3 deep cycles are required to completely erase any memory issues. I will check the entire pack for water levels this weekend. A spot check showed that most levels are ok, but were checked while the pack was fully discharged. It has to be checked when fully charged.
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