solar and lipo charger

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stinkbutt
 
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Joined: Wed Feb 17, 2010 2:40 am

Re: solar and lipo charger

Post by stinkbutt »

Two things you can try:

1. Verify you're hooking up the pot's terminals correctly. (Sorry if this is an insulting suggestion - Kinda like "Your computer's not working? Have you checked the plug?") If you're not hooked up to the middle terminal then it really won't make any difference at all - The resistance between the two outer terminals is always pegged at 10K, it's the resistance between the middle and the outer two that change.

Chances are, you're reading that thinking - Yeah duh. Can you get to something useful now?

2. Try leaving R(prog) out entirely. That will reduce the maximum current from 200 mA to 100 mA.

If that still doesn't work, then I would guess there's something wrong with either your solar panel or your lipo charger. You could try just blasting the solar panel with a ton of light and see if that solves the problem, (stick it in front of the headlights of your car if you don't have access to direct sunlight at this time of year, which much of the northern hemisphere does not.)

If you have high-power resistors you can try putting it in series with the panel to make sure the panel can actually source 1A when it's getting more than sufficient sunlight/headlight, but high-power rated resistors tend to be expensive.

I once saw that Australian multimeter junkie use a trick: substitute 10 1/2 W resistors for a precision current sense resistor since it's much cheaper just to wire 10 of them in parallel: They each dissipate 1/10th the power. I'm sure it's an old trick but it was new to me at the time. That'd work too, though to simultaneously drop 8V and pull 1.25A you'd need an effective resistance of 6.4Ω (not a big problem) spread across 20-25 1/2W resistors or 40-50 1/4W resistors. That's a lot of soldering.

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