Polymer Lithium Ion Battery - 20mAh

Replacement: None. There is no current replacement for this battery. We are no longer able to source this size, sorry! This page is for reference only.

This is an extremely tiny and light weight battery based on the new Polymer Lithium Ion chemistry. This is the highest energy density currently in production. Each cells outputs a nominal 3.7V at 20mAh. This may sound small, but the cell is less than an inch square!

Comes terminated with a standard 2-pin JST-PH connector - 2mm spacing between pins. These batteries require special charging. Do not attempt to charge these with anything but a specialized Lithium Polymer charger. Battery includes built-in protection against over voltage, over current, and minimum voltage.

Note: Be careful with the JST connectors. They can stick in pretty good and tugging on them can damage the connector. Check this tutorial for an easy way to remove them safely.


Weight: Our scale doesn't go this low


2C continuous discharge - very high for low price Excellent long-term self-discharge rates (<8% per month) Robust power source under extreme conditions (-25 to 60C)


JST connector Digikey 455-1734-1-ND (Top Entry) Digikey 455-1749-1-ND (Side Entry)

* * 0.7x0.65x0.125"

  • JST connector
  • Digikey 455-1734-1-ND (Top Entry)
  • Digikey 455-1749-1-ND (Side Entry)


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • who / about 13 years ago / 4

    can anybody say rechargeable LED throwy

    • How would you get it back?

      • NXTreme / about 12 years ago / 2

        Giant vacuum cleaner? Like, really, really, really giant vacuum cleaner?

      • The Doctor Doge / about 9 years ago / 1

        You don't. Recharge it with a mini solar cell

      • FRISBEE STYLE !!!!!!! :D

      • Frapsy / about 12 years ago / 1

        It could have a tiny pic on it with an electro-magnet and an infrared receiver so with the push of a bottom it turns the magnet off and falls back but that would probably need a bigger battery.

  • jessef / about 13 years ago / 2

    does sparkfun have a Li charger with a current limit lower then 20mA. Charging a 5C with the MAX1555, that most sparkfun chargers seem to use, doesn't seem like a good idea.

  • Member #325574 / about 10 years ago / 1

    Hello everybody, when is this battery going to be back to stock???? Any idea? Where to find a similar battery in the market?

  • otorresbaca / about 11 years ago / 1

    Any ideas on how to make a small wireless charger for this battery?

  • richswartwout / about 12 years ago / 1

    does anyone know how long this battery would last if hooked up to 2 ultra-bright leds?

    • KudaMuda / about 11 years ago / 1

      How much current do the ultra-brights use? Typically they're ~20 mA. I just built a mini-keychain flashlight using this battery, one 265,000mcd led (from electronic goldmine) and Sparkfun's LiPo Charger Basic. I used a momentary switch to cut down usage and heat. It will be noticeably dimmer after a dozen or so 20-30 second bursts. The light in theory should continuously discharge for about an hour. In parallel the same LEDs would use double the current and shorten the battery life before charges. If you're going with two LEDs why not step up to the 110mAh battery? I'm going to for my next flashlight. But then I plan on using a bigger LED too!

  • My scale reports 2.1 grams, including JST cable and connector. The battery alone is 0.9g. By comparison, the coin cell is 6.6g.

  • I'm finding the 20mAH rating too small when compared to the rechargeable coin cell ( http://www.sparkfun.com/commerce/product_info.php?products_id=8818 ) which is approximately the same volume -- this may be half the volume, but certainly not 1/10th.

    • looks like space-wise the Li-Ion is better, but when weight matters LiPo is better

    • N8B / about 12 years ago / 1

      I'm guessing some of the bulk is packaging. So, the major advantage of this over the coin cell is the all ready to go JST cable.

  • Gabe / about 13 years ago / 1

    Amen to that.

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