It's sunday and you need to charge a 18650 or any 3.7 volt Li-ion
Well you don't have a charger for it well is easy to fine one if need one bad
All you need is friend that uses them cheap E-cigs
They come with one of these

some come with a cord like this I now have maybe 5 from them throw away cigs like this one
but there all the same.

These are really nice they tell you which pad is + AND -
I solder 2 wires on that to fit my 18650 and hour later it was charged and ready to go.
These could easy be added to about any uC project.
Really small and easy to fit into any small box to charge a 3.7 volt LI-ion

 

I have several charger and battery packs from E-cig kits the local gas station was selling for a $1. They are a cheap portable power source with just a little work for direct access to battery power.

 

Pretty slick and one of those things I never really thought about. Thanks for sharing.

Ron

 

This type has a 350mAH battery. The plastic charging cap is glued to the metal base so you pop it off with a jewelers screwdriver and connect your wires to the battery pads on the PCB for a power source with a USB recharge port.