6v Solar Panel Charger
How to reduce a varying voltage to 6V DC?
I have a solar car charger that produces 15 to around 22V (it varies according to light levels). I want to reduce this to around 6 volts (it wouldn’t matter if it varied a couple of volts) so that I can charge a 6V battery. The solar panel produces around 100 to 120mA.
Thanks billrussell. Just a couple of things more to ask now. 1: Where and which way to i put the diode (it’s just a little black cylinder shaped thing with the white stripe -isn’t it?) and 2: So there is no risk of overcharging even though the solar charger is meant for a 12 volt battery?
What you need is a current controller in between the panel and the battery. Over voltage is not a problem, as the battery will reduce it to 6-7 volts. The problem is the current. If the charger’s output of 120 mA is more than the battery can safely handle, then that has to be limited.
If the battery can safely charge at the max output of the charger, 120 mA, then you can just connect the charger directly to the battery, possibly through a diode to prevent reverse current when the charger dropped below 6 volts.
If the max safe charge current for the battery is lower, say 50 mA, then you need a current limiter, which you can do with a few transistors and a resistor.
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