5PCS 2S 7.4V 8.4V 8A 18650 Charger PCB BMS Protection Board for Li-ion Lithium Battery Cell

So far, so good. Made a pack of 2x18650 in 2S configuration.voltage initially was zero, but just plugged in the charger, and it activated. Voltage output was about 8.14v (because the batteries were almost fully charged). Plugged in charger, light on charger was Red, then after about 1 minute it switched to 10.3v and the charger light went Green. Which is what I expected. Works great so far!

It's always frustrating to buy a widespread and simple product like this only to find that it does not work. All the boards received did not function; often, the voltage of a fully charged 1S cell was reading 2.5V with the protection circuit connected

These work very well. Only one of the five I got was bad. The rest worked perfectly. The wiring diagram, using the 18650 batteries, helps you figure out how to connect them. I used three-battery holders that allowed me to hook everything up very nicely. Only one of the boards was bad. These boards protect against short circuits and overcharging. I've tested both, and they work as described.Update:The seller sent a replacement, so I have a complete set of boards. I've been able to make several battery packs using the 18650 batteries. This board makes the packs safe from overcharging and overdraining. It's a smart board that signals the charger when the pack is fully charged. I'm quite impressed with these. The schematic on the selling page gives you exact connection instructions. I've tested the packs for shorts, leaving the charger on for extended periods, and draining the packs to the point the board turns off the power (protecting the batteries). Very good engineering.

The media could not be loaded. I was pulling my hair out trying to figure out WHY! This BMS wasn't working. Then after reading other buyers review I found out that u must "initiate" the BMS. I did that and BAM! it started working.Ironically I designed this 20,000 mAh variable power supply to be free of houshold power to be used while traveling and or camping BUT I needed to plug it into a household outlet to initial the dang thing. Lol 😆 I find that ironic.Anyway, the BMS is up and doing its job. I do wish for led indicators, red for charging, green for cutoff voltage has been reached and a flashing red LED if a problem occurred. I would think that would be a simple adjustment to this somewhat simple design. Anyway I like the size! I am using to charge 21700 cells (I hope it works). Im still wiring the rest of the project so I will soon see if it works.I wil update with data.Dave C. Stout

The board works, just watch out for all the things mentioned in the other reviews. Here is a summary, along with a few extra concerns. This pic was before I cleaned up a few of my solder joints, but the board functionality is confirmed good. The board arrived on time, with the included 2 PCB's incased in a small sealed ESD Bag.1) This cost is a few $ too high, given that there are 40A boards available for the same price. This is 5A.2) Check all solderpads make connection to the other side of the PCB. Use an ohm meter to confirm this prior to build. Mine were fine. Yours may not be based on previous reviews. If you have a problem, you'll have to manually solder a small jumper to fix it.3) Would be nice if this board came with double sided tape or something. Would help address the cost concern on #1 above.4) P- and P+ are a bit close together. They do provide short protection, but be careful there. Wish they would have had another 2mm or more of separation for safety sake.5) When you initially complete your build, the board will not work. Beware! It's not a problem though:You just have to expose it to a small external charger (in my case of a 4S1P - I put it on the charger at 100ma for about 30 sec, and all was good for that point forward). After you do this, the boards voltage output will start.6. The board's size is great for these smaller batteries.7. Amazon seemed to be able to ship these boards quickly, unlike several others...8. I cant seem to find much vendor support for this board. So if you are outside of Amazon return window, you are in trouble... The vendor is supposedly, Anmbest (Wuhan) Control Tehnology Co.,Ltd.If the cost were a buck or two lower, I'd give it 4 stars.If the P pads spacing was better and the whole 'boot-strap it with 12V+' thing didnt occur, I'd give it 5... or if the amerpage capability was 10 or 15A...Anyways, go for it ... just beware of the limitations. This is a 5A board, you wont be powering anything too large with it...Hope this helps!

! Model: 4S !! Batteries: Lithium Ion Batteries 4 cells in series @ 14VDC 15A 210W !! Charger: random wall adapter @ Input: 100-240V 50/60Hz Output: 12V 500mA!This works great so far but beware, mine didn't work until I hooked it up to a charger when I did thatI guess it activated the BMS part of the circuit because after I unhooked it from the charger and the P+ and P- were outputting the expected voltage. Then I tested the short circuit protection and it worked I tested it by quickly connecting positive and ground together and it sparked and popped but the batteries didn't get hot or explode and the BMS the same so it appears the short circuit protection works.One last thing to mention one other customer review said that the wiring diagram was messed up because the positive notch on the lithium ion was connected to the ground, essentially meaning that the battery was connected backwards he is totally correct, please do not connect the battery that way.Also another customer review had a wiring diagram which is easier to follow his wiring diagram is a little bit easier to digest.P.S the solder pads have these weird small metal plates on them you can remove them by heating them up with a soldering iron and pulling them out with tweezers (for me the P+ P- didn't have the plates)Overall great product.