Fool-Proof 5V charging circuit design

[Newtopprojects]

Can someone please advise how to design or find aFool-Proof simple and low cost design for a very low power 0.5 W / 5V charging circuit to charge a small 3.7V LiPO battery. The power source is a stable 5 volt that can be connected to in either way. This is for a very low budget application.

Any guidance will be greatly appreciated.

 

[Delta Prime]

To design a full proof low cost 0.5 watts , 5 volts, 100mAmp charging circuit for a single cell Lipo battery you must consider
Using a tiny hamster wheel connected to a mini generator
It could be the most adorable and energy efficient charging solution.
Or if you got a dollar?

 

[AnalogKid]

Lithium batteries, even small ones, must be charged correctly. This involves both voltage and current monitoring. At your power level, there is no way you can build one for less than you can buy one. ebay is your friend.

ak

 

[Bluejets]

Use as DP showed above and set the charge rate by changing the charge sense resistor as shown in the spec sheet from the manufacturer for recommended charge rate for you cell size.