I have found an old and broken solar phone charger at my sisters place and decided to give it a second life and reuse it. First idea was to replace the old battery and solder it back but the size and specifications was hard to find anyway this i why i decided to add 4 AA 1.2V rechargeable batteries to it so i could use them instead of the main battery.
Step 1: Remove the Old Battery and Solder the Wires.
First step is to remove the old battery and recycle it, i have thrown away the old battery before i decided to write this instructable so no picture available for it unfortunately. Please recycle all your batteries as even a small battery is causing lots of negative impact on the environment. I would recommend to be careful when removing it as it can short-circuit, leak, explode and so on.
I have used a voltmeter to be sure where to solder the + and - wires and to check if the device generally, still works . Of course i have used the red wire for the + and black one for the - .
Step 2: Solder the Battery Holder and Add the Connector.
I have used the voltmeter to check where it gives the maximum voltage in order to avoid soldering the wires to the spots where are not all the of the batteries connected. All the 4 batteries give about 5.4 V output without being connected to anything.
I have used the 12V DC connectors i bought on the e-bay for my another solar project but i guess smaller ones would fit better for this size of the wires. Wire the connectors both for the battery holder and the solar charger.
Step 3: Final Check and the Charger Assembly.
A quick check before putting all the screws back and looked like everything worked just fine.
Assembled the unit back, i was lucky that this particular charger had some holes probably for the ventilation and i have put the wires though them but if your charger doesn't have it, i guess is not an issue to drill some tiny holes for the wires.
Luckily i had an old Samsung which i didn't use for a year or so and the battery was completely empty, i have connected it to the charger and it started to work. The batteries i am using here are 2000mAh and they charged the phone from 0 to 62% before they completely died. I am happy anyway as its original battery was 1100mAh looks like i doubled the capacity but i will buy some 3000mAh batteries to be able to charge my other phone to 100% with one charge.
Now i have a solar charger for AA batteries that i use a lot for different appliances.
* I can charge any 5V devices( i have even started my Raspberry PI with this one but not sure how long it will work though).
* I can check the status of 4 batteries using the built in charge indicator.
* I have saved another device from being thrown away for recycling.
* I can charge the AA batteries from the laptop usb port, from my other bigger solar batteries project, and any 5V usb source, it can charge itself from the sun as well(i know it will take lots of time as the solar battery is quite small).
* I have an emergency charger, as i like camping and i use a camera, radio, flashlight and all of them are using AA batteries.
This is my first instructable, i did my best and hope you enjoy it.