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