I was wondering; since a bms can put a load on one cell group to bring it in line with the others, can you also charge one cell group independently of the others? For instance , if you have all groups at 4.1v , with one group at 4.0v , can you just attach a 4.1v supply to that low group and " catch it up " with the rest without having to disconnect it from the pack?
Cell balancing
- Thread starter Dak77
- Start date
Yes, any power supply, DC converter or RC hobby charger that includes 1S capability will do.
But then you may as well use a 4S or 8S match whatever your pack is "balance charger" to do the balancing rather than the puny BMS.
There are also dedicated balancing gadgets that do not charge, offer no protection, just balance, some with 5A balancing current available, can start at whatever voltage you like, e.g. 4.05V
So many ways to skin that cat.
But then you may as well use a 4S or 8S match whatever your pack is "balance charger" to do the balancing rather than the puny BMS.
There are also dedicated balancing gadgets that do not charge, offer no protection, just balance, some with 5A balancing current available, can start at whatever voltage you like, e.g. 4.05V
So many ways to skin that cat.
e-beach
10 MW
If you don't trust the cheap bms, just test your cells for balance once a week. If you find they are not balancing after a 12 hour charge or so, then get something to bring your cells into balance, a better bms or another charger.
However, unless you run your pack to near or to low voltage cutoff often, balancing once a week is fine. Balancing once a month might be fine as well, depending on how often you deplete you full capacity.
Also, if you are having balancing problems, is your pack old? Does it have one on more bad cells?
People worry about balancing when it is less critical then balancing every day.
However, unless you run your pack to near or to low voltage cutoff often, balancing once a week is fine. Balancing once a month might be fine as well, depending on how often you deplete you full capacity.
Also, if you are having balancing problems, is your pack old? Does it have one on more bad cells?
People worry about balancing when it is less critical then balancing every day.
dogman dan
1 PW
While you can bump a cell group up with a cheap power supply, the best approach is an inexpensive RC charger. It will stop at perfect full charge. I forgot a wall wart once, and way overcharged a cell once.
Something like the B6, which can be set to 2 amps max, and 1s. Then use something you make yourself to attach it to the bms plug, using the same two female slots you tested the voltage from. 2 amps is fine for the tiny wires, but when balancing, you will usually see much less than that flowing.
You can also discharge a high cell using the same charger. Check often, but only balance when you need it. You don't really need it balanced to .01v. balance to .1v at most. Any more is just worrying about two watthours, on a cell group that holds 100 or more wh.
Something like the B6, which can be set to 2 amps max, and 1s. Then use something you make yourself to attach it to the bms plug, using the same two female slots you tested the voltage from. 2 amps is fine for the tiny wires, but when balancing, you will usually see much less than that flowing.
You can also discharge a high cell using the same charger. Check often, but only balance when you need it. You don't really need it balanced to .01v. balance to .1v at most. Any more is just worrying about two watthours, on a cell group that holds 100 or more wh.
Voltron
1 MW
Had a few that were so out I was charging a section at the same time as draining other sections with wired bike lights as the bms was taking way too long. Got good at judging the voltage rebound after removing the load and was able to get them right in with the middle range ones.
e-beach said:If you don't trust the cheap bms, just test your cells for balance once a week. If you find they are not balancing after a 12 hour charge or so, then get something to bring your cells into balance, a better bms or another charger.
However, unless you run your pack to near or to low voltage cutoff often, balancing once a week is fine. Balancing once a month might be fine as well, depending on how often you deplete you full capacity.
Also, if you are having balancing problems, is your pack old? Does it have one on more bad cells?
People worry about balancing when it is less critical then balancing every day.
They're fairly new cells. Just from different batches. Some were 3.65v and the rest were 4.1v . I've had to get creative to get them all together only having 1 hlg-480h-54a and 1 24v cheapo sla charger , but one group is just about .006v below the rest. I figured it isn't critical for them to be perfectly matched since I'm staying between 4.05v and 3.6v, but I'm ocd I guess.
999zip999
100 TW
What size is your battery ?
999zip999
100 TW
You just use a phone charger after you fully charge the battery to brimg up one low cell . You must check with meter the output of the little charger. No you not just read the printed case. Must check voltage and polarity. Then you must seat and watch as Dogman said do not leave. If you must leave unplug.
Your battery is only as strong as your weakest cell.
Your battery is only as strong as your weakest cell.
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