Charging a small 3.7v battery from USB

Hey guys! I had this little flashlight that worked great for years. I would plug it into the USB port on the computer to charge it. When it broke I took it apart and it had a small battery connect directly to the 5v and GND of the USB cable. Is it OK to charge these small 3.7v batteries from just 5v without having to make a circuit?

Is ok to just hook them up to 5v?


NO! Li-pols are very strict on there charging needs and require a charge controller.
HavocRC (author)  mpilchfamily4 years ago
I wonder then why that flashlight just had the battery connect directly to the 5v and it never broke. Wait, is it because of the little circuit that's inside the battery tape?
If there was a small circuit board attached to the battery then it had the charge control built into the battery.