Instructables

Solar LED Light Hacked Into Solar Battery Charger


This is a very simple instructable.  Really, it's more of an informable than instructable since it's pretty self-explanatory.  I know there have been many other solar battery chargers, but this one was already made and sitting under my nose.

I posted this instructable the day I made it, so the jury is still out on how well it will actually work.  I'm hoping for at least "kinda works, eventually."

Executive Summary:
Get cheap solar light.
Remove LED light from circuit (cutting it works fine).
Use existing rechargeable battery in system, or modify AA battery holder to hold AAA battery.

Hungry for more details?  Read on...
 
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Step 1: The Backstory

This project started last Christmas when I found a pack of 6 solar powered LED Luminaries at Ollies (a discount close-out store similar to Big Lots, no telling what they might have, but it's gonna be cheap!) for $6. Yes, they were $1 each. When I opened them up, I found they were a solar panel connected to a rechargeable AA battery and a flickering LED. I was thinking about using them for the sun jar project and away into the garage they went.

A few months went by and I bought some cheap mp3 players for myself and the kids (also at Ollie's). Under $10 each, so no bells or whistle and they work fine.  However, they run on AAA batteries. Regular AAA .  Batteries get expensive fast, so I figured a rechargeable battery would be the way to go.  Even better would be a solar powered recharger.  Off to the garage to find the materials.

Yeah, I'm a cheapskate.  In fact, I'm so cheap I didn't even put a picture on this step!

Step 2: Materials Needed

Picture of Materials Needed
What you need -

Solar powered light
Rechargeable batteries (if the battery in it doesn't fit your device.)
Small tools - screw driver, snips, etc (not pictured)

I found some solar lights in a dumpster a while ago and decided recently to put them to use as battery chargers.
In the ones I have, the LED is on all the time, which means if left in the circuit it is wasting 11 mA of charging current (I measured it) during the day. So I removed the LED. Even with the LED removed the charging current was only 14 mA. This was measured indoors through a window in the evening, so let's say 20 mA outdoors in mid-day. You can see that with the LED this is just generating enough power to light the LED through the night.
With 20 mA charge current, it would take 100 hours, or about 10 days, to fully charge a 2000 mAh battery. So you have to be patient.