LilyPad Basics: Powering Your Project

Contributors: Gella
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Power Options: Rechargeable Lithium Polymer Batteries

Many LilyPad products come equipped with a JST connector designed attach a 3.7V Lithium Polymer (LiPo) battery. These boards include a built-in battery charging circuit to recharge the LiPo when connected to a computer or wall wart via a USB connection.

LilyPad ProtoSnap Plus

LilyPad ProtoSnap Plus

LilyPad Arduino USB - ATmega32U4 Board

LilyPad Arduino USB - ATmega32U4 Board

LilyPad MP3

LilyPad MP3

LilyPad Simple Power

LilyPad Simple Power


LilyPad Arduino Simple Board


LilyPad Simblee BLE Board - RFD77101

2 Retired

SparkFun carries a variety of 3.7V Lithium Polymer batteries that are compatible with the LilyPad system. The capacity of the battery will depend on the intended run time of your project, size constraints, and other factors.

Lithium Ion Battery - 400mAh

Lithium Ion Battery - 400mAh

Lithium Ion Battery - 850mAh

Lithium Ion Battery - 850mAh

Lithium Ion Battery - 2Ah

Lithium Ion Battery - 2Ah

Lithium Ion Battery - 110mAh

Lithium Ion Battery - 110mAh

Lithium Ion Battery - 6Ah

Lithium Ion Battery - 6Ah


E-Textiles Battery - 110mAh (2C Discharge)

6 Retired

Lithium Ion Battery - 1Ah

8 Retired

Using a LiPo Battery and Battery Charging

Each LilyPad board with charging capabilities has a default charge rate. If this default charge current is set to 100mA, so a 100mAh battery will recharge in one hour, a 1000mAh battery in 10 hours, etc. Since the board is set to charge at a rate of 100mA, we do not recommend connecting a lower capacity LiPo battery (i.e. 40mAh LiPo battery) to charge.

To recharge an attached battery, plug the board into a USB power source. While the battery is charging, the "CHG" LED will illuminate. When the battery is fully charged the LED will turn off.

Connecting a Battery

Inserting a LiPo battery into the JST port on a LilyPad ProtoSnap Plus

It is safe to leave a LiPo battery attached to the board permanently, even with USB power applied. The battery will not be overcharged. We recommend you do not leave a charging battery unattended.

The battery connector can be a tight fit and difficult to remove; when disconnecting a battery never pull on the wires. Use a pair of needle nose pliers or cutters along the plastic to gently pull the plug out of the connector.

Remove LiPo Battery

Tip: there are two small "nubs" on the top of the plastic battery connector that can be shaved off with a hobby knife to make the battery easier to remove.

LiPo Battery Safety and Care

While LiPo batteries are a great option for providing rechargeable power to your project, they do have some safety considerations. This section will cover tips for safe handling and use of LiPos for your projects.


  • Always store your batteries in and enclosure free of sharp objects. When installing a battery in your project, take care to keep it away from parts of your project that could pinch, poke, or strain the battery.

  • Do not transport or store a LiPo battery with metal objects, such as hairpins, necklaces, or any other conductive object or material.

  • Keep or store the battery in a cool and dry place/environment while installed in a project or in storage. If you are not planning to use your project for a long time, remove the battery and store it separately.

Keep Away from Heat and Moisture

  • Keep your LiPo battery away from environments that will damage it. Do not immerse a LiPo battery in liquids. Remove the battery from your project if it needs to be washed.

  • Do not use or store the battery near any source of heat. To secure a battery to your project, velcro is a temporary option or sew into a pouch or place in a plastic enclosure. Never iron or hot glue directly on or around a LiPo battery.

Strain Relief

One of the down sides to using these LiPo batteries is their fragile power connections. These type of batteries are manufactured for a permanent install in devices, and not being removed often as can sometimes happen with wearables. It can be easy to accidentally pull or break the power wires from the terminals on the safety circuit built into the battery.

You can provide strain relief to the wires by placing them to the side and securing with electrical tape - this will help with strain on the connection to the battery when pulling on them to remove.

Electrical tape around the wires of a LiPo for strain relief

Inspect Battery Before Each Use

  • Short circuits or damage to LiPo batteries may not always be noticeable - check the battery for puffiness, heat, or other changes. If the battery looks damaged, remove immediately.

  • If the battery gives off an odor, generates heat, becomes discolored or deformed, or in any way appears abnormal during use, recharging, or storage, immediately remove it from your project or battery charger and stop using it. Make sure to dispose of your batteries properly - do not throw them in the trash! Contact your local e-waste disposal organization for details on how to discard batteries in your area.