On Thursday, 11 April 2019 17:09:45 UTC+1, wrote:
On Thu, 11 Apr 2019 04:32:29 -0700 (PDT), "
wrote:

Keep that solar panel trickle charger. It will be a much better bet.

Peter Wieck
Melrose Park, PA

Speaking of solar chargers, I have one charging the 6 volt battery in
my Ford 9N tractor. The panel is rated at 7 watts max. Here in the
great Pacific Northwest, with the cloudy days and all, The thing is
charging at about 17 milliamps. Open circuit voltage is 18 volts. But
when the thing is connected the battery voltage measures at 6.5 volts.
So I don't think there is any danger of overcharging unless the sun
goes nova and really lights the panel up. But I was wondering how to
calculate the wattage. is at 18 volts times 17 mA or 6.5 volts at 17
mA? I think I should use the open circuit voltage but I don't know.
Eric

It's delivering 6.5v at 17mA. 6.5 x 17m = 110mW, 0.11 watts.
At 18v it would deliver less current thus less power.


NT