6/11/2018 Update: Pointed out in the reply below from DK Tech Kyle, we now offer a charger. You can see it as Digi-Key part number 1568-1748-ND. Thanks for pointing this out, Kyle!
Here is a put-together solution to help recharge these batteries.
You will need:
- Sparkfun’s Li-Poly Charger - part # 1568-1299-ND
- A battery holder such as BH-18650-W-ND
- JST wire lead assembly - part # 1528-1126-ND
- A 5V power source with one of the following options:
– A Mini-B USB Cable from your computer such as one of these
– A wall wart with a USB port or Mini-B USB cable such as one of these
– A wall wart with a Positive Center 2.1mm ID / 5.5mm OD barrel plug such as one of these
This system will be capable of charging one 3.7V 18650 battery at a time.
For more information, check out Sparkfun’s LiPo USB Charger Hookup Guide.