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Old 04-16-2014, 03:07 PM   #10 (permalink)
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The power supply looks very nice and highly accurate. I still think a dedicated charger will be better.

A charger can charge at 5A. That means you can charge a set of cell is ~1 hour. 2 hours at 3A. 300mA will take 20 hours.

Knowing discharge is more important than charge.
To know your SOC state of charge you need to measure how many mah come out of the battery. The charger will do this by measuring the current out and multiply it by the time. So 700ma for 1 hour is 700mah. But the current changes as the battery discharges. So the charger will do this in 1 second increments. To know your battery SOC do a full charge, charge until voltage drops 5-7mv per cell. You know it is full. Then discharge it fully to 0.9 -1v per cell. The total discharge will tell you how much capacity your cells can hold. Then to do it right. Fully charge them. Let them sit for a week and discharge them. That will tell you how much self discharge is happening over a week.

You will not find a charger that can do this for the entire set. It would run at 180-200V.

I'm thinking of building a system that will cycle the battery like you said. My plan is to connect a set of wires, cut an extension cord and leave female side out next to headrest. Then do discharge connect a 500W shop light to it. Making a circuit to turn it off at a voltage is much harder. Then you can hook up the power supply at a low current 300ma and charge it over night.
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