Hi all, I've been reading for hours, and I've found a number of answers to questions I have had, and read a bunch of messages about similar things I want to ask, and even searched some but nothing quite like what I was hoping for, so here goes:
I purchased 4 used battery packs which are 36V nominal, 21Ah 10s x 6p, 748Wh each. LG cells rated at up to 10A discharge, and they've all charged and balanced very well. These are extremely well made and have a charge port with an XT30 connector, and a discharge port with an XT60 connector. The BMS on these is 'locked out' because these are supposed to communicate via CAN with a dashboard unit I don't have, so I've bypassed the BMS for discharge. Now I was thinking that I could probably parallel them easily enough with something like the product linked below, which probably results in some losses, but is using a MOSFET I presume to watch draw on both packs in order to keep them at the same level:
https://www.amazon.com/CONHIS-MOTOR...&pd_rd_wg=FNYtN&pd_rd_i=B099F2QGTF&th=1&psc=1
I believe that this would allow me to charge them individually while connected through the device above through the XT30 as long as power wasn't on- does that make sense?
Next, what I'd really like to do though is to set these up in 2s 2p for 42Ah and 72V. Perhaps there's something like that available for running packs in series? Or maybe this as simple as creating a series connection between two of these. I know it's probably a bad idea-- but I've already bypassed the BMS on discharge, and I plan on setting the current well below the cell max, as well as not abusing it on discharge. I'm looking at the Flipsky 75100 for a controller which is limited to 100Amp draw.
I know I'd be better off removing the BMS, installing a 20s BMS and repackaging the batteries, but the whole thing is so nicely put together and the quality of the board is obvious, I'd rather trust this BMS for charging than getting some junk. I know it does work in series, because there's at least one person who has a video of it on YouTube. I guess I'm trying to justify a charger and BMS and rewiring vs, letting them do their thing. Should someone talk me out of it? Probably...
I purchased 4 used battery packs which are 36V nominal, 21Ah 10s x 6p, 748Wh each. LG cells rated at up to 10A discharge, and they've all charged and balanced very well. These are extremely well made and have a charge port with an XT30 connector, and a discharge port with an XT60 connector. The BMS on these is 'locked out' because these are supposed to communicate via CAN with a dashboard unit I don't have, so I've bypassed the BMS for discharge. Now I was thinking that I could probably parallel them easily enough with something like the product linked below, which probably results in some losses, but is using a MOSFET I presume to watch draw on both packs in order to keep them at the same level:
https://www.amazon.com/CONHIS-MOTOR...&pd_rd_wg=FNYtN&pd_rd_i=B099F2QGTF&th=1&psc=1
I believe that this would allow me to charge them individually while connected through the device above through the XT30 as long as power wasn't on- does that make sense?
Next, what I'd really like to do though is to set these up in 2s 2p for 42Ah and 72V. Perhaps there's something like that available for running packs in series? Or maybe this as simple as creating a series connection between two of these. I know it's probably a bad idea-- but I've already bypassed the BMS on discharge, and I plan on setting the current well below the cell max, as well as not abusing it on discharge. I'm looking at the Flipsky 75100 for a controller which is limited to 100Amp draw.
I know I'd be better off removing the BMS, installing a 20s BMS and repackaging the batteries, but the whole thing is so nicely put together and the quality of the board is obvious, I'd rather trust this BMS for charging than getting some junk. I know it does work in series, because there's at least one person who has a video of it on YouTube. I guess I'm trying to justify a charger and BMS and rewiring vs, letting them do their thing. Should someone talk me out of it? Probably...