IMA battery smart discharger
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smart discharger
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We will soon have a nice overnight charger, so the final component required for a fully automatic grid cycler is a discharge monitoring system that can accurately detect when any of the ten 12 cell subpacks that are tapped and appear on the BCM connector drop below 12Vor 1V/cell.
The same circuit will also detect a rapid cell drop off if it happens before the 12 cells get to the 1V/cell level as will happen when a cell reaches depletion before the rest of the cells in the 12 cell string.
Reading the BCM to get the cell drop out detection will be the best way to do the detection, but we are not sure that the BCM reports that information or if it simply terminates assist when the cell dropout is detected.
a totally independent circuit seems like a better solution at this time.
I started the project by mounting all the required components to a large perfboard. The circuit performs well, but one issue came up that I overlooked. The 160 ohm thermistors in series with this circuit will give false voltage readings because of the 160 ohm series resistance. The best solution I can think of so far would be to clip 1A fuses across each of the thermistors, thus making a safe but very low resistance tap to the battery during the testing.
Like all of this type of project, the devils in the details.
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