SquirrellCook
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Am I missing something, it looks like your claiming to charge already charged batteries?My original post made some assumptions, one of which was that a horizontal solar panel and it's controller would be capable of charging a battery from sunrise to sunset.
At midsummer day here at approximately latitude 52° sunrise is at 04:42 and sunset at 21:24, resulting in a day length of 16 hours 42 minutes. Unfortunately I don't have a screenshot of the solar charger output on midsummer day to allow comparison of daylength and charging time, but do for the Autumn Equinox:
View attachment 57923
As can be seen, the system was charging the leisure battery for 12 hours 48 minutes at the Autumn Equinox.
On the equinox one would expect 12 hours of daylight at pretty much any latitude, but there are several different ways (surprisingly!) of defining these things and using the definition I've used, sunrise was at 06:46 and sunset at 19:01, giving a day length of 12 hours 15 minutes.
There's reasonable agreement between daylength and charging time at the Autumn Equinox.
On midwinter day here at approximately latitude 52° sunrise is at 08:06 and sunset at 15:52, resulting in a day length of 7 hours 46 minutes. The solar system data on midwinter day was:
View attachment 57921
As can be seen, the solar system was charging for a total of 7 hours 3 minutes.
Again, there wasn't bad agreement between daylength and charging time.
On midwinter day the weather here was appalling with dark skies which means that the only solar energy reaching the solar panel was light scattered by thick cloud - so the light intensity was much attenuated. This would affect the start and stop times of the solar charger, resulting in reduced overall charging time.
In summary the assumption I made in the original post was reasonable to a first approximation.
Colin
