3Pcs 3S BMS 12V 10A 18650 Lithium Battery Li-ion Protection Board

I had to revise my review. After reading other comments I found it was my fault the first one didn’t work. I failed to put a charge voltage on it the first time. Once I put a quick voltage on it (even though the batteries were already charged) it now works.

Works perfectly with my 21700 3s2p setup!

Others have complained about applying a charging current to the pack for it to start conducting. I mean, that's fine with me haha. I can't imagine a scenario beyond mass manufacturing where you'd build the pack and then send it off and needing it to work without charging it even once. I got my batteries off of a site and they came in at- what- 3.1 or 3.2V? Like yeah of course I'm going to charge it before I actually use the pack haha.Anyways, my reason for giving 4 stars instead of 5 is that there's a loose metal plate on top of the solder pad on the component side of the PCB. So, looking at the top of the thing, there's B-, B1, B2, and B+ right? On each one of those four solder pads there's a thin metal rectangle that's apparently in place via a thin layer of solder. It's bizarre and, in my opinion, a dangerous decision to make because it isn't obvious unless you accidentally get a bad solder like I did. I had a great solder between the wire and this weird, secret rectangle, but the rectangle almost completely detached from the PCB. I ended up heating and removing these rectangles and soldering straight to the PCB like a regular guy. If the seller could chime in on why these are here, I'd appreciate it and would consider revising my rating.

No issues at all. Made 3 battery packs using 3, 18650 cells. These prevent overcharging, and shut down when voltage is low. Exactly what I needed. +++++

I've ordered these twice now as I like the small size....fool me twice I guess. But they are too unreliable. Out of six, I don't have a single working one. I started ordering a different model by a different seller and they all work, right out the gate...no "tricks" to "activate" them.I have been building battery packs for a long time so I'm not a novice. I've followed the instructions regarding charging them and it just never works. I've spent so much time trying to get these work...that it's silly.Try your lick with the square shaped, higher current version of these that you can find an amazon. These are just garbage.

One blew up immediately after i tried to discharge from it, i wired up another one the same way and it worked, it charges and discharges just fine, so far. Still kinda lame i payed for 3 and maybe only got 2 working ones, (i haven't tested the last one yet.)

I used this to build a battery it work right away one thing though it doesn't say this in the instructions it comes in a safety mode so you can connect the battery cells you MUST appy a charger to the finished battery to take it out of safety mode even just for a second you wont get an output until you do i see a bunch of people say it didnt work but you HAVE to charge it first

Worked wonders! Converted our nursing facilities feeding tube machines that works on 12v 2amp lead acid batteries to 18650 lithium batteries..bench tested for a week draining the diy battery pack and charging it back multiple times in the our baxter infusystem feeding tube machines before sending it back to the floor for patient use..5 done, 10 more units to go.. just do remember they need to be charged 1st before its going to work.. its for safety reason they did this for it to work the very first time..there will be no voltage outputted if you don’t charge this on your first use so be aware..