Thread: 12v charger and dual battery

Originally Posted by wozzlegummich

Unregulated, the solar panels current is all over the place. Regulated, it depends on the type of regulator.

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My 80W solar panel is rated at 4.7A at 17V output, and 5.0A at short circuit. Hardly all over the place. So long as the sun shines squarely on the panel the current will flow until the battery is cooked. As you say, the regulator is the key to limiting both current and voltage output but you need to choose the regulator wisely.

Hi again Mundy and bee utey pretty well covered it.

While the output current of a solar panel will vary with the amount of sunlight, or lack of sunlight hitting the panel, the maximum current the panel can produce is the controlling factor.

An 80w solar panel will produce, at very best, about 3.5 amps. This 3.5 amps and the start of Charge of the battery(s) will determine the voltage at which the battery is charging at, and this charge voltage will continually increase as the battery charges.

With an alternator, because even a very low battery will only pull about 35 amps max, and an alternator can easily produce 80+ amps, the voltage will remain the same and at the regulator setting for the entire charging duration.

It’s the high current capacity of the average alternator that gives an alternator a big advantage over anything else and why it’s constant voltage means you can easily charge a number of different types of batteries at different SoC and all will charge properly to a fully charged state, without effecting any other batteries in the set up.