5 PCS 2S 20A 7.4V 8.4V 18650 Li-Ion Lithium Battery 18650 Charger PCB BMS Board with Balance

Did what I expected. During one of my tests, the charging voltage reached 8.5V using a 9V/5A power supply. No dramatic heat dissipation observed, the maximum charging current reaches 2A for dual 3500mah batteries. Discharging works great for small loads under 5A without any issues.

These little charging pcbs do work, but they dont come with any diagrams or information in how to connect them. I have one in a small rc car thats running on 2) 112245 3.7v lipo cells out of some disposable vapes in series connected to one of these balance charge modules. I am using a 9v usb-c pd trigger board for an input and regulating the output back down to 5v with a small buck converter. It seems to work just fine for this setup.

Purchased a portable oscilloscope that used an obsolete and impossible-to-find 8.4 volt sealed lead-acid battery. 2 18650 Li-Ion batteries and this 2S BMS board solved the problem.

so far so good

all failed after 1 year use.

Calidad

Works great with a caveat: it can't handle initial starting current of a 7.2v cordless drill, but once it starts the circuit handles the high torque current just fine. I was modifying an old Dewalt cordless drill from Nicad to Lithium Battery, I ended up having to wire the drill directly to Battery, while this charger circuit only for charging, that little socket on the battery pack is the new charging port, it looks weird, but I have a new and more powerful drill.

These boards do not have any charging circuitry. They are only protection and balance boards. The only ICs on this board are one HYCON 2120 battery protection chip, and two HYCON HY2213-BB3A balance chips. The balance is controlled by a 43 ohm resistor which will dissipate about 100mA. This will deliver full voltage limited only by power supply current or battery internal resistance to your cells until one of them hits the overvoltage protection limit. This means there is no saturation or topping charge. In my experimentation, the 9V 2A power supply delivered 2A continually until one cell hit the high voltage cutoff. The power supply was current limiting at 8.53V at that point, and the pack voltage was 8.47V. Both balance chips were dumping 100mA, but since there is no charging IC to limit the voltage to 8.4V it had little effect. It gets 2 stars because they do function as a BMS with balance if you can supply the board with 8.4V from somewhere else, but I was expecting to be able to feed a 9v USB-C PD trigger board and get CC-CV charging with balance. That is not what they boards do.