Camera Batteries to power Arduino

Hi!

I'm about to make a project portable and want it to be powered by a rechargeable 1S 3.7V LiPo cell. While browsing for batteries, I found out it is really hard to find good "standard" universal batteries which are also shipped internationally. However, it is easy to find replacement batteries for phones and cameras.

Would it be possible to use these batteries for my project? I could solder wires to the connectors on the batteries and charge and use them with one of the charge and protection circuits available from China.

What do you think? While we're at it: Why do these batteries always have 3 connectors? 2x ground or something different?

Cheers!

Edit: I found out about the 3rd pin. Most likely, it is linked to a thermistor. Edit: I can take care of getting the right input level. My actual question is just if I will be able to charge those with the usual charging circuits.

The charge circuit you are speaking of may just be protection circuits that cut the battery off at 4.2 and 2.7 volts to prevent damage. They are NOT charging circuits if they are same as

http://www.dx.com/p/charge-discharge-protective-circuit-board-for-rechargeable-li-ion-batteries-13-4mm-1-7mm-26114#.VQL4XxjXerU

However if you use a very low current supply such as a 1W 6v solar panel (with Zener to drop to 4.5v) where the controller is used simply to limit over charge, and the panel is unable to supply too much current, you may be able to use it.

Weedpharma

A USB power pack contains a battery, charging circuit and outputs a clean 5V - these would be ideal but often they switch off if the current draw is below a threshold (since they are designed for recharging phones) - ie they are not universal USB supplies...

Thanks for your responses so far.

I didn't have a specific in mind, this one is the first I found: http://www.ebay.com/itm/1pcs-5V-MICRO-USB-1A-Lithium-Battery-Charging-Protection-in-one-Board-Module-/121147545969?pt=LH_DefaultDomain_0&hash=item1c34f4d971

The mobile battery pack is a good idea, but already a bit big. I would be willing to sacrifice some mah for size. 500-1000mah is already enough.