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Oct 04, 2015, 05:42 PM
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Accucell fail


It's a good time to reveal to the world that the Accucell 8150 doesn't really balance anything. It appears to spend most of its time with the balancing resistor network on, then briefly float the balancing pins every few seconds, presumably to determine what cell is high. It can't determine the high cell when the resistor network is active, even though the LCD clearly shows it. The Astroblinky used the same cycling algorithm, for some reason. 1 cell usually ends up over 4.20 during the floating.

It might actually work if the difference is < 0.01V but lack enough effectiveness for 0.05V. It would be worth trying the astroblinky with a bunch of voltmeters to see if the astroblinky was equally ineffective. The accucell's cell readout revealed severe imbalance in a 2S & a 3S.

The mane cause of unbalancing seems to be the temperature differential between the cells. In high current applications, the inner cells get hotter than the outer cells & discharge faster. This causes the outer cells to discharge less & overcharge.

In low current applications in hot weather, the outer cells heat up from ambient air before the inner cell. This causes the inner cell to discharge less & overcharge.

In the 2S hand controller, body heat heats up 1 cell faster than the other. Ideally the current usage & enclosure would heat all the cells evenly.

The only way to manage the unbalancing is independantly charging the cells instead of relying on a resistor network like modern chargers. This would be very expensive, requiring independent MOSFETs.
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