cellphone battery charging

I was looking for a cellphone battery to power my smart watch.I mean the ones that can be used and charged at the same time.The problem is I don't know how to charge the battery.Here is the link for the battery: http://www.amazon.com/gp/cart/view.html/ref=gno_cart
As you can see, there are 4 pins.One of them is labeled ground and the other is + voltage.So there are two pins left.I am using this charger:https://www.sparkfun.com/products/10217
How should I charge the battery?

zack1544:
http://www.amazon.com/gp/cart/view.html/ref=gno_cart

That link goes nowhere.

sorry this is the link:
http://www.amazon.com/LGIP-520B-Lithium-Cell-Phone-Battery/dp/B0015A4TQK/ref=sr_1_2?ie=UTF8&qid=1414898301&sr=8-2&keywords=cellphone+battery+1000mAh

Why not just use a standard 1000mah lipo from sparkfun designed for that charger? It's rpobably the same size or smaller than the phone battery you have anyway

http://www.ebay.com/itm/5V-Mini-USB-1A-Lithium-Battery-Charging-Lipo-Charger-Module-for-Arduino-A866-/131304520047?

The lipo battery from sparkfun can't be charged and used at the same time.

zack1544:
As you can see, there are 4 pins.One of them is labeled ground and the other is + voltage.So there are two pins left.

When packs had three pins the third was a thermistor output (measure the temperature of the pack). I'm not clear on the specification when there are four pins, but I know from having a bad phone battery that without it the phone will not be able to determine the state of charge of the battery. There must be some type of coulomb counter IC inside the pack and the extra contact (or both contacts) is used for data communication with it.

Suffice to say that, unless you're building millions of cell phone units with such a battery and you want to ensure that one-in-a-million doesn't explode in the user's pocket, you can ignore those extra contacts.