Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 1200mAh for a total of about 4.5 Wh. If you need a larger battery, we also have a 2500mAh+ model

The batteries come pre-attached with a 2-pin JST-PH connector as shown and include the necessary protection circuitry. Because they have a high quality JST-or-compatible connector, the cable won't snag or get stuck in a matching JST jack, they click in and out smoothly. The cables are rated for 2A so if you use them keep that in mind.

The included protection circuitry keeps the battery voltage from going too high (over-charging) or low (over-use) which means that the battery will cut out when completely dead at 3.0V. It will also protect against output shorts. However, even with this protection, it is very important that you only use a LiIon/LiPoly constant-voltage/constant-current charger to recharge them and at a rate of 500mA or less.
Like most lipos, the batteries we sell do not have thermistors built-in. This is why we suggest charging at 1/2C or even less - 500mA max in this case which is how much you can get from a USB port.

Additional safety notes: Do not use a NiMH/NiCad/lead-acid charger! Also, do not abuse these batteries, do not short, bend, crush, or puncture. Never charge or use unattended. Always inspect batteries and surrounding circuitry constantly for any damage, loose wiring, or the possibility of short circuits. Polarity matches all Adafruit LiPoly/LiIon chargers and boards, other brands may have reverse polarity and can destroy your battery. As with all Lithium-ion polymer batteries and with any power source - they should be used by experts who are comfortable working with power supplies.