MakerFocus 6pcs 2A 5V Charge Discharge Integrated Module 3.7V 4.2V for 18650 Lithium Battery with Charging Boost Mobile Power Protection PCB Board Module

I bought these for a series of single LED flashlights Iw as building. I was looking for a small form factor when I got these, and boy it sure is small. I love the battery status LED's on the side of the board. It added functionality that I wasn't originally planning to add. My biggest problem with these boards is because they are so small. it's easy to let the smoke out while soldering the wires to the board. That issue is 100% my fault though, and wouldn't be an issue if I could have soldering the wires to this board first. But my design didn't allow that.

These look nice, but I really wish it was easier to use the 5V output. Sending a signal every 5 seconds with a micro controller is a pain. I mostly just would love to find a module that can charge a lithium ion battery over micro-USB and have it also have a built in 5V regulator too. I know the Adafruit Powerboost does that, but they cost $15-$20 each. This device is so close to doing that. Edit: I found out why I had to keep activating this module to keep the power output on. This module auto detects current draw. If it is high enough it will keep the 5V output on. I was trying to keep an Arduino in a low power state then occasionally waking it up to transmit a radio signal which can draw a lot of power for a few seconds. My current draw on the Arduino was way too low so this module would shut itself off. The only way to keep it on was to send the button input on the board a low signal every so often to prevent it from turning off. I couldn’t find any detailed information on these modules, but I figured these out when I tried using them again for a portable LED project. When I woke up the module and the brightness on my LED board was high it would stay on indefinitely. If my brightness was low when it first woke up it would shut off by itself after 30-45 seconds. If it woke up on high brightness and I switched it down to low without restarting it then it would still stay on indefinitely. Kind of odd behavior, but now that I understand these modules these are great for many use cases. I love how the push button on the side acts as a power switch. Press once to wake it up and press it twice to turn it off.

These boards are solid. It's nice to have something rated for 2amps in such a small size. I used these with a raspberry pi and some other peripherals without issue. I would like to point out that these aren't necessarily "maker-friendly" though. Unlike similar boards like Adafruit's PowerBoost series or Helder's RetroRSU, these do not have a simple enable pin. They do have a "power on button", but this works by needing to be pressed and released to turn on and off, instead of the traditional EN pin which is pulled high/low and remains in the same state as long as the EN remains the same. In short, this means that you can't realistically connect a typical sliding power switch and instead must use a momentary button. This could be a deal breaker at worst, or like in my case, somewhat inconvenient and awkward to use. I do suspect that these are designed for use with power banks, which would explain the power on/off button behavior. Another thing, they seem to have an abnormally high quiescent current draw. This means that when the device is powered down but the battery is still connected, power will be drained from the battery. In my project, I find that pulling it out of a drawer after a few days of not using it, it is always dead and has to be charged before I use it each time. Again, annoying for me, but not a deal breaker although it may be for others. So based on your application these may or may not be well suited. If these do not work in your case, I recommend looking into alternatives like the Adafruit PowerBoost or Helder's RetroPSU.

The bad: It says 2.1A output current but I tested two of them and got ~250mA and other things you might not like is the four LEDs are on while charging and discharging (not good for low power circuits but good for showing remaining power) and the output is on (with no way to turn off) while charging. The good: The output voltage is a solid 5V and while pulling the max I got of ~250mA the voltage only dropped to 4.89V. You can take all the LEDs off without affecting the circuit or just leave the one "100%" marked one and it'll only turn on when fully charged. The form factor is great and the gold contacts are cool. TLDR: Not the best for higher current projects 250mA+ or low current projects under ~5mA! All numbers were my results, yours may differ. I like it.

Good charge + discharge board. Robust pads are easy to resolder and the pcb is heavy duty. They output 2+ amps and ripple is < .02V. My gripe is with the leds and Vout voltage. The leds are unnecessarily bright as heck and such down too much juice from the battery. V-out is only 4.65v and not close enough to 5v to run a RPi without complaints. I have to add a booster on V-out which is addt'l $10 project cost.

Easy to connect (must have a good ability to solder wires to the board). Charges 18650 batteries while indicating the level of charge of the cell. The only thing I would change is to make the charge indicators different colors instead of all red LEDs.

If you build or repair battery powered stuff, you should always have these around. They actually perform to spec and work reliably without any fuss. I've powered Raspberry Pi 4 computers with these running off lipo batteries, and even under load they keep spitting out those sweet, sweet 5vdc pixies. My only complaint is that the solder pads for hooking it up are really close together, too close to solder wires directly to the board unless you've got a steady hand. Because there's a ground pad on both sides of the Batt +, it's super easy to short the battery when soldering and blow either the board or the battery. Ask me how I know.