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

Used this to revive a flashlight which had a single 18650 battery inside for light. When the charger died I thought it was done for and would need to be replaced, but then I found these. They work terrific for charging 1s and similar voltage devices. Like any charging device like these I would strongly advise you don't use this like a pass through to keep a item charged While still actively using it. As they can get hot. I usually stick a mini heatsink on devices like this but since it's for a single flashlight I charge once every other month it is fine and doesn't get so hot it burns out. These are ideal for charging a single battery at a time. If you have multiple batteries or the battery in question has a large capacity definely look into a heatsink or it can overheat with extended use. And I wouldn't advise you use this to keep power going on some project actively in use for hours or again, heat can cause it to burn out or become a problem. I've wired similar devices in parallel so one usb connection powered three of these chargers at the same time to charge three cells (one 18650 per charger) but you have to make sure your usb power brick can handle the load if you're going to do that!

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.

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.

Small lithium ion chargers, just as described! I prefer to attach an additional heatsink to keep the 4056 chip cooler during charging.

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