Small 3S 18650 Li-ion Charge Controller


New Member
Mar 30, 2021
Just like the title says, I'm looking for a small and inexpensive 3S 18650 solar charge controller to recharge a 3S battery pack I made. The battery pack has a BMS on it and the panel I'm going to use is a 15 watt, 18v max panel.

I've looked around everywhere and unless I want a big bulky "expensive" (it admittedly is only $35) charge controller like this one from renogy, I seem to be out of luck. I have found small charge controllers but they seem to be only designed for lead-acid batteries with a cutoff around 14.2 volts, much higher than the 12.6 max charge voltage for my 3S battery.

Do I even need a solar charge controller if the battery already has a BMS that would theoretically cut off the voltage when it's full?


Solar Enthusiast
May 25, 2020
Thats a water proof one. THe wanderer is cheaper (I got mine for 10).

You can set the cut off as low as 12. The BMS may not cut out on a high voltage condition (18v from your panel). Or it may not charge at all when it sees 18V.