I have a 16s Daly BMS. I need to balance my cells but do not have a 48v battery charger. I can split the cells into 4s and use a 12v charger, but I do not have a 4s bms. Is there any way to use the 16s bms but on a 4s battery configuration so I can charge them in 4 rounds using the 12v charger? Later , I can parallel them all and top balance in the usual way once they are all almost fully charged.
Charging 4s battery with 16s BMS LiFePO4
- Thread starter Dunkirk
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sunshine_eggo
Happy Breffast!
Not as 4S.
You could build the 16S battery and charge the last 4 cells, i.e., (+) on cell 4 and (-) on BMS output, so it can interrupt the current.
Once 4 are done, you would breakdown, move the 4 to the far end and then rebuild. Charge the next 4, etc.
You could build the 16S battery and charge the last 4 cells, i.e., (+) on cell 4 and (-) on BMS output, so it can interrupt the current.
Once 4 are done, you would breakdown, move the 4 to the far end and then rebuild. Charge the next 4, etc.
MisterSandals
Participation Medalist
Why do you need to balance your cells and do you expect your BMS to have enough balance current to balance your cells?
Could you explain that connection a bit more please.
sunshine_eggo
Happy Breffast!
Try this:
This won't allow you to balance, but it will allow you to get them fully/near-fully charged 4 at a time.
This won't allow you to balance, but it will allow you to get them fully/near-fully charged 4 at a time.
Samsonite801
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Yeah, that's what I was going to say too, no need to tear the 16s down, just charge up 4s at a time using the 12v charger...
Or if you had a regulated power supply that can do cell level voltages, can charge up individual cells, one at a time, or take the pack apart, and parallel all cells and charge on cell voltage using CV, and no BMS, just don't set the CV higher than max safe...
Last edited:
sunshine_eggo
Happy Breffast!
If you don't tear it down to shuffle cells, there is no BMS protection. That's the point. Charge fast and safe.
Samsonite801
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Yeah just make sure your 12v charger can't over-volt the group (like it's a LiFePO4 charger or 12v PSU set to not over-volt the group)...
I thought the whole purpose of the bms is not to overvault the group.
This takes several weeks using a power supply at 3.6v with all 16 batteries in parallel.
I could try this. I forsee a situation where the 4 batteries being charged will trigger a bms shut off once voltage rises and there is a sizable gap between the 4 vs other 12 batteries.
If you are building a 16s battery what will normally charge said battery? Are you building a PV/SCC array after the battery is built?
Almost seems worth it to invest in the PV array and charge it as you would in the final build out and let the BMS do its normal BMS type thing.
That or find a cheap 48v charger, they aren’t that expensive.
Almost seems worth it to invest in the PV array and charge it as you would in the final build out and let the BMS do its normal BMS type thing.
That or find a cheap 48v charger, they aren’t that expensive.
sunshine_eggo
Happy Breffast!
Assuming 280Ah cells:
280*16*0.5/24/10 = 9.3 days if done properly.
That's the intended situation. You charge those 4 to cut off. Shuffle the pack, do the next 4, etc., until all 16 have been charged 4 at a time.
I connected an balancer with 5A (chinese) balancer current. That means, it works perfect for 1A. So I charged tho whole 16S Battery to 3.35Vx16=54V with 5A. Then I changed the charging current to 1A/56V and the cell gets balanced in about 4hours.
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I connected the balancer only for initial balancing! After that, the BMS internal balancer should be do its job.
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de.aliexpress.com
I connected the balancer only for initial balancing! After that, the BMS internal balancer should be do its job.
Samsonite801
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Yeah but I guess I was saying that when you're charging only 4-cell groups with a 12v charger, you're not charging through BMS protection, so you need to manually monitor cell voltages to make sure you are not at risk for going too high on any one cell in that group.
For me, if I needed to balance a whole pack faster than the normal BMS passive balancer can do, where the bank needed to stay online (and I couldn't disassemble the pack), I would just put on one of my JKBMS 2a active balancers, and let it do it automatically, and let it take as long as it wants, then it can balance on the cell-level without any risk, and you don't have to babysit it.
