The LiFePO4 battery that I used had a built-in battery management system
(BMS) which balanced the cells and it came with a "smart" charger
designed specifically for that battery (according to there
specifications). Though, according to the spec sheet, I could leave it
plugged in continuously, I set it on a lamp timer and charged it a
couple of hours per day when parked in the hangar. On safari, I removed
the batteries and charged them in the motel.

To use a solar panel I'd get a charge controller designed especially for
lithium batteries.


On 6/4/2016 9:48 PM, Brian wrote:
That is simply my point about the controller Richard recommended, I just don't know what the efficiency of it is.
7ma loss would be excellent.

The controller is inexpensive enough I may order one and measure the efficiency.

Flying everyday, my panel doesn't usually fully recharge the battery in between flights, If I don't fly for a day to two I will disconnect the panel as I agree it would be easy to overcharge the Lead Acid batteries. That is one of my concerns about going to a LIPO4 battery, with the flat charge/discharge curve it may be harder to tell when it is getting close to fully charged, compared to Lead Acid battery.

Brian

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Dan, 5J