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A 3.2-3.6 green forward voltage LED , uses 2 ma. to operate? What amperage can it safely handle? Answered

I would like to use one as a charge indicator for a 2500ma. rechargeable AA battery connected to a 2v., 600ma. (full sun) solar panel.
2v. solar + 1.2v charged AA battery = 3.2+ v. and should turn the LED on, but can it handle the amps. or does it need a resister in the curcuit to protect it?




9 years ago

As a general rule most standard LED's have a forward voltage close to 3 volts at approximately 20 miilamps recommended operating current. They will light at a lower current of course, with a maximum of around 30Ma. Your solar panel puts out 2 volts in full sun at 600Ma you will have to limit the charge current and possibly fit a series diode from the panel if not already fitted to prevent the battery feeding back through the panel. Solar garden lights use single panel cells to charge an AA battery... plenty of circuits on the web to look at . Your LED idea is out as it stands.

If the LED forward voltage is >3V, you'll need 2 solar panels (in series) to drive current through it. But that's going to leave you with less than 1V for charging - no good. You'd really want to build a charging circuit for this.

You're going to want a resistor to protect it, trust me. That said, if you are more curious about the current your LED can handle, check the DC characteristics on the datasheet, and it should specify a max forward bias current (called I_max or something of the sort).