Quote:
Originally Posted by redpoint5
I don't think the solar panels are a good idea unless you have overcharge protection for the battery.
EDIT: Perhaps wire in LEDs/diodes across each cell to balance and provide some level of overcharge protection. I had a solar panel connected to supercaps that had LED balancers, but the sun was overpowering the LEDs ability to bleed excess charge.
30 mA still seems too high of a parasitic load. Do gauges really consume that much when the car is off? My vehicles are all down below 10 mA now.
I'd run the 20 Ah battery to avoid using the solar panels, which will probably overcharge the 7.8 Ah battery.
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The battery does have overcharge protection, at least it's advertised to have it. It is also advertised to have cell balancing built in.
However I don't think I need to worry about that. If I short the cells out when they're sitting in sunlight that brings them to maximum open circuit voltage, there's <40mA current. So at 14.2V they would not exceed 20mA, so the car could be sitting in noon sun constantly and be fine.
I tested it yesterday and to my pleasant surprise, the array measures >16V while the sun is about to set, so this is good. It should be providing at least 10mA for many hours a day, which should put a big dent in the parasitic current draw. I'll be watching the battery voltage closely to make sure nothing is wrong, but I am 99% sure it will still be drawing net current.