LilyPad Basics: Powering Your Project
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.