![enter image description here][1] [1]: /editor/20150903/55e81806c762f.jpg Introduction Lithium Polymer Batteries are a very common source of power today. Many electronics gadgets have one inside, and they have some reasonable features. I’ve bought great batteries, with different sizes and capacities for my electronics projects. So long I’m using this batteries, coming the problem: charge them. Charger Version 1 So, we start to find the correct circuit for my DIY charger. After some Google research I found the Maxim MAX1811 IC. It’s a single-cell Lithium battery charger that can be powered directly from a USB or from an external supply up to 6.5V. It’s use a SO-8 Package, easy to solder and can be sampled at Maxim. Other chip features are: You can select between 4.1V and 4.2V battery regulation point; • You can select between 100mA and 500mA current drain from USB; • There’s a open drain pin (pin_8) for signaling end of charge condition (2.5V