Solar Charger

[icoms8]

Im wanting to build some simple, portable things for every day life. And i want to start out with a solar battery charger. If i hook up a solar panel straight to the batterys in a holder. will it charge them? Or do i have to add something?

[robojohn]

The Answer is "YES" You have to ad a diode between the battery and the Solar panel otherwise the current will leak out of the panel over night or during low sunlight.

A common diode to use is IN4002, Or In4004. You could Salvage one from almost any power supply or Buy one from dick smiths for around 50 Cents or less.

Current can only flow in one direction through a diode and so will allow the current to flow into the battery but not out the other way.

Simply solder it to the red wire.
The direction of flow is identified by a thin white line at one end of the diode.

[Soeren]

Hi,

Besides the diode, you also have to select a solar panel of the right voltage and current rating.

What are the specs for the battery you want to charge?

[icoms8]

I want to charge two AA Nimh batterys.

[Soeren]

Hi,

What is the capacity of each cell?

[robojohn]

Most off the shelf rechargable AA batterys are 1.2V 650mAh or 700mAh.

Of course higher capacity cells are also available.

Should be written on the side of the batterys or on the packaging.

[Soeren]

Hi,

Most off the shelf rechargable AA batterys are 1.2V 650mAh or 700mAh.

It's been a couple of decades since I saw AAs that low. The NiMH cells I use on the job is 2700mAh (and AAAs at 900mAh).