My battery's go from 8.2v fully charge to 6.2v as soon as I power my ps2p and when I turn it off they go back up to 8.2v I'm using 18650 no Bms charging with external charger.
That board does the balancing and power management by itself. You'll be able to use any 9v-15v provided it can supply enough current. Just get one that has a current rating sufficient to run the console and charge at the same time.Thanks for the reply I'm new to using batteries will this work https://www.ebay.com/itm/311721987212 and do I have to cut the power from the BMS to the portable while charging since the bms needs 9v.
Also can I use any 9v power source to charge batteries or do I need a special charger