Battery Question

[scienceguy8]

I want to try building a BEAM robot around an old cell phone battery I recently obtained. In order to stick to the spirit of BEAM robots, it will also have solar panels so that when the battery dies it can just sit there and recharge. However, I have never used a solar panel to charge a battery before and would like some advice on what the panels' voltage should be and how they should be wired to the battery. The battery in question is a 3.75 V Lithium Ion battery with a capacity of 1100 mAh. It has three terminals: a positive, a negative, and an unmarked third.

[HarryBotter]

I'm not sure that I'd charge a Lithium Ion battery this way unless I was watching it very closely. You could easily end up with a fire if you over charged the battery.

However, I wouldn't be afraid to charge NiMHs or NiCads by just creating a solar cell array that provided slightly more voltage than the cell's design voltage. If you know the amperage the cell array is providing you could just time the charge.

[alain]

To allow your battery to last long enough, you have better to buy or to build an appropriate battery charger, especially for Li-Ion battery. Solar panel are sometimes sold with a regulator which can be used for lead-acid, but never for Li-Ion.
You can find very cheap kits at your electronic shop or by web, lextronic, and a lot of other robotic website sellers.