Cells drop a bit after they charge, more with some charging systems, less with others. I often loose a couple hundreths of a volt by morning if I charge at night.
Also some BMS have some power drain. Excessive drain from your BMS can indicate a bad BMS.
if you unplug your BMS, you should be able to tell how much drain your BMS is imposing on your pack.
Also check the individual cell voltages to make sure your BMS is not faulty and trying to kill one of your P groups.
Like @iamasalmon said, check each group to see if they are balanced and lose voltage equaly or maybe there is just one bad cell which should be replaced. I had one bad cell killing other 11 cells in 12p. It just drains voltage sitting on the table, doing nothing else.
Btw it would be smart to get charger which chargea to 42v. Overcharging is never good.
And another point here - CC/CV charging will bring full voltage to battery in last part of charging cycle and it will charge on full voltage for some time, until battery is full. Maybe you just didnāt charge it to 100%?
Itās a 4Ah pack at 2a for about 6 hours, starting at about 40% charge, pre balancedā¦Iād imagine thatās more than enough to bring to full charge
the top row is a different p group. the connection between the two p groups are in series. the current that flows is only the current that is delivered by each p group, right? that would be five cells at ten amperes each into two busses, twenty five amps per bus
Okā¦ Iām wrongā¦
Iām going to delete my nonsense comments
Clip the corners of them nickel strips. Donāt need to round them off just take a diagonal cut on each corner so they donāt stick out so sharp.
Oh yes, my favorite. High resistance contacts and cascade failure. Send me 100.
Ummmm, I got some for shits and gigs. Maybe use under low, low power?
what happenedā¦ I only could bear watching until the 45 second markā¦
itās more relevant to powerwall builds with salvaged 18650s where youāre running 80-200P
To be clear, this was for a charge-and-ride mppt bank of lƩ tired cells
Ah, yeah I get it. I guess its an easier alternative to fusing rows of P groups.
Would someone please look at my wiring diagram and the bms diagram below and let me know if what Iāve drawn matches up?
Thanks!
looks good to me
yes, but only if you want to discharge though your BMS. This is generally not a good idea for esk8, since it will protect your battery at at the cost of your face.
