LilyPad Basics: Powering Your Project
Gella 
How Long Will My Project Run on Battery Power?
To figure out how long your project will run on battery power, you need to know two things:
- how much current your project uses
- the capacity of your battery
Battery capacity is given in milliamp-hours (mAh). This number tells you how many milli-amps (mA) a full battery can provide for one hour before it’s empty. The e-Textiles Battery that comes with most LilyPad Arduino kits has a 110mAh capacity. For many projects, especially ones with a large number of components such as LEDs, you will probably want to use a higher capacity battery for a longer run time.
Thus, an e-Textile battery will only power the project for approximately half an hour. Here's an instance where a larger capacity battery would make sense, if the project needs to operate for a long time, such as during an event or showcase. The trade-off is that a higher capacity battery is also physically larger -- make sure to plan accordingly for proper battery storage/attachment on your project to reduce strain on the wires and fabric.
Here are some typical runtimes for various SparkFun batteries and numbers of LilyPad LEDs/LilyPixels:
| Number of LEDs | 1 | 2 | 5 | 10 | 20 | ||
| Battery Name | Battery mAh | Hours of Operation | |||||
|---|---|---|---|---|---|---|---|
| Polymer Lithium Ion Battery - 40mAh | 40 | 1.3 | 0.8 | 0.4 | 0.2 | 0.1 | |
| E-Textiles Battery - 110mAh (2C Discharge) | 110 | 3.7 | 2.2 | 1.0 | 0.5 | 0.3 | |
| Coin Cell Battery - 20mm (CR2032) * | 250 | 8.3 | 5.0 | 2.3 | 1.2 | .61 | |
| Polymer Lithium Ion Battery - 400mAh | 400 | 13.3 | 8.0 | 3.6 | 1.9 | 1.0 | |
| Polymer Lithium Ion Battery - 850mAh | 850 | 28.3 | 17.0 | 7.7 | 4.0 | 2.1 | |
| Polymer Lithium Ion Battery - 1000mAh | 1000 | 33.3 | 20.0 | 9.1 | 4.8 | 2.4 | |
| Polymer Lithium Ion Battery - 2000mAh | 2000 | 66.7 | 40.0 | 18.2 | 9.5 | 4.9 | |
| Polymer Lithium Ion Battery - 6Ah | 6000 | 200.0 | 120.0 | 54.5 | 28.6 | 14.6 | |
* Note: the Coin Cell Battery is non-rechargeable.