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Solar Panel Help

goodjboy

Apr 27, 2012
10
Joined
Apr 27, 2012
Messages
10
Hi,

I got a 30 watt solar panel that I measured (not in the full sun) that puts out over 20 volts. I have not measured the output in direct sun but I imagine it is around 20 volts still.

My ultimate goal is to charge a bunch of rechargeable D batteries using this 30 watt panel. I found on Amazon a 12v device that charges two pairs of D batteries and I was thinking of getting a few of those devices and hooking them into my 30w panel.

What efficient solution can I use to make the voltage coming out of the panel be 12v so that I can power the battery chargers?

Is there a better method than using the battery chargers to use my 30 watt panel to charge a bunch of batteries?

Any advice would be greatly appreciated!

Thanks :)
 

goodjboy

Apr 27, 2012
10
Joined
Apr 27, 2012
Messages
10
The panel is rated to be 17.5 volts by the manufacturer. I must have measured the voltage without any load.
 

Wabajig

Apr 14, 2012
75
Joined
Apr 14, 2012
Messages
75
What type of battery is it, nickel cadmium, lithium, standard alkaline, carbon zinc, etc? I suppose I should assume the battery charger is made for your batteries, but they all draw current differently. The safe bet would to trickle charge a motorcyle battery with 12V series pass regulator, and run off the battery. Also use a heatsink on the transistor. Good luck.
 
Last edited:

Wabajig

Apr 14, 2012
75
Joined
Apr 14, 2012
Messages
75
Sorry about my late edit, had a customer. Just use the batteries they recommend though. Look up a series pass circuit, and for the zener use 13V and the resistor in series should 220 ohm / 1/2 watt. Transistor selection should be an NPN with a gain of 100 or better with power dissaption with heatsink of 20 watts min. Hope that helps, John
 
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