UMLIFE 10 Pack Ultra-mini USB Type C 3.7V Lithium Battery Charger Board 4.2V Charging Module with Protection Circuit and LED Charge Indicators 5V USB-C Input

Excellent product

Use these chargers on out door light fixture that uses 3.7 v battery to charge battery. It works great it the photo cell doesn't change it. Just takes little wiring and soldering.

I used these to charge lithium batteries (two, in parallel). Works well. Does not charge fast, but I did not need fast charging.

Excellent size, easy to use, definitely seems a great value, and nice build quality. I dig the USB-C power input port, as I want to migrate away from as many of the older USB styles as possible to minimize the variety of cables I need to keep around. Details I observed: The "Battery+" and "Output+" terminals are electrically bonded together. The "Output-" and "Battery-" terminals are electrically isolated. The unit's output is 4.2V DC when plugged into a USB-C power supply, and will drop to the lipo cell's voltage when unplugged from USB-C power supply. It does not have an onboard voltage boost circuit onboard, so if your project demands a solid 5V output, plan accordingly to add your own separate voltage booster to achieve 5V output - not a big deal, but I figured that may be noteworthy to someone. YES, it can indeed act as an Uninterruptable Power Supply for devices running off 4.2V DC or less. If you include a 5V boost circuit on the output, it would likely be perfect as a USB UPS device (think: powering a Raspberry Pi when the main power is lost). I'll be using one of these to convert a low-current smart scale I bought many years ago, which runs on 3 AAA batteries, to being USB rechargeable, using with a lipo cell I recovered from a disposable ... ahem, "product." The rest will go into my parts kit, for future conversion projects. I'm happy with this product.

Good product

For so long I have been making my own charger for 3.7v Liop batteries, and while it works well, it only has a single light indicator the goes out on charged. It allows charging if there at a time, but plugged in the wrong order for just one or two, it starts to fry itself.. These here show red or green depending on charged it not, they allow two batteries hooked up and have a input terminal for things like, what else but, 5v solar paneling! Plus easy convenient Type-C porting. These things are a no brainer. The effeciency of the solar panal use is like non I ever did get able to work, when developing solar circuits myself. In short, if a battery is at zero charge, I have yet to find a way to recharge when the application is also wanting to up and running already, I'm not so advanced These are a charm.

Works fine, Used in a few projects that didn't require a boost converter.

Perfect for 18650 batteries and even pouch cell lipos.