Review on 🔋 Premium 5PCS 1S 3.7V 4A 18650 BMS Charger PCB Protection Board for Li-ion Lithium Battery Cells by Lauralee Jensen

My Revain electrically heated gloves were a BARGAIN for the price I bought them for. but inside were LiPO batteries in 2S configuration (4.2 + 4.2 = 8.4V) which died after one full use! In fact I think the controller circuit didn't have any low end cutoff and I left them on until they died and of course ruined the batteries forever. My plan was to replace them with double capacity Lithium 18650s (not LiPO), but I had no idea how to charge them in a 2s configuration. After some searching I found this product. I bought a holder for two batteries, soldered this board and they worked! (The photo shows the temperature in the glove). The circuit board is tiny and adds no bulk to the battery. Added heat shrink tubing to keep everything in place and my cheap (but warm!) gloves lasted another season! You now have twice the lifespan. So far I've tested them with the original 8.4v glove charger - they charge well (and don't get hot). I drained them to zero and recharged them, no problem at all! [PS: I took my 18650 from a discarded iHome 10000mAh battery - the USB port was broken but the batteries were perfect! The output is exactly 0.000V. This infuriated me, and I even plugged in a second one, concluding that I had somehow messed up the first one (or was it defective?). Luckily I remembered one of the helpful comments. BTW, if I wanted to make battery packs with removable batteries, I would have to short them EVERY TIME I reconnect the batteries. Others have suggested connecting to a momentarily closed switch to "initialize" the IC each time.