Proper process for balancing two Dyness batteries

denmendez65 said:
Yeah but how does that help the batteries having equal charge?
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They already have equal charge. Its the BMS SOC counter in each battery that needs to sort themselves out without inverter interference with the BMSs.
 
SauRoNZA said:
No idea how it works exactly, but it’s the recommended process when adding a new battery.

I think it just locks out any discharging and then pumps it to 100% from grid/solar and keeps it there.

The BMS then sorts itself out when all the batteries are completely 100% and balanced out.

Otherwise the collective array reports 100% too early and before all batteries are actually at that level and the inverter starts using it.

Had this exact same problem when I added my 4th battery.

Activate battery I seem to recall also forces the inverter itself not to be powered from the batteries.
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@wingnut771 His post basically says that the batteries aren’t because the collective bank is reporting 100% when some of the individual batteries aren’t.

I agree with @SauRoNZA
 
denmendez65 said:
@wingnut771 His post basically says that the batteries aren’t because the collective bank is reporting 100% when some of the individual batteries aren’t.

I agree with @SauRoNZA
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How do both batteries report 100% and then when discharging the one says 40% and the other 60%?

edit: anyway, the activate feature sounds like a simple process to try anyway and probably ends up doing the same thing I'm talking about.
 
wingnut771 said:
How do both batteries report 100% and then when discharging the one says 40% and the other 60%?
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If it was LA batteries I could tell you for sure. Resting voltage matters when determining SOC. lithium I don’t know. Do they report 100 when connected together or disconnected? And does lithium need to be left standing for a couple of hours to verify the SOC like LA? I haven’t researched my on how BMSs report their SoC.

If one says 40 and the other 60 when discharging then they most definitely couldn’t be at the same SOC to begin with. Or there is a problem with one being discharged quicker than the other. Or one has a faulty cell and is working as a 15 cell battery?

Will powess had all his batteries connected at the same SOC then he started charging and discharging them. And because the cabling wasn’t done in a way to properly cajrge and discharge them equally, some batteries drifted during the one charge/ discharge cycle quite a bit. One battery was pulling for example 20A and another 10 amps.

Doesn’t matter if they are in parallel, they will never balance and share the load
 
denmendez65 said:
If it was LA batteries I could tell you for sure. Resting voltage matters when determining SOC. lithium I don’t know. Do they report 100 when connected together or disconnected? And does lithium need to be left standing for a couple of hours to verify the SOC like LA? I haven’t researched my on how BMSs report their SoC.

If one says 40 and the other 60 when discharging then they most definitely couldn’t be at the same SOC to begin with. Or there is a problem with one being discharged quicker than the other. Or one has a faulty cell and is working as a 15 cell battery?

Will powess had all his batteries connected at the same SOC then he started charging and discharging them. And because the cabling wasn’t done in a way to properly cajrge and discharge them equally, some batteries drifted during the one charge/ discharge cycle quite a bit. One battery was pulling for example 20A and another 10 amps.

Doesn’t matter if they are in parallel, they will never balance and share the load
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Its a lucky packet on how BMSs report 100%. They all have different rules and criteria.

In Wills case, yes, the different resistance from having a stack of batteries without a busbar would cause this. Again, not an issue as when they get to the bottom the slow batteries will catch up.
 
wingnut771 said:
The fast batteries resistance goes up so the slow ones with high resistance become lower comparatively speaking.
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But won’t the inverter kill the charge thinking the bank is full? When will the lagging batteries ever charge?
 
denmendez65 said:
But won’t the inverter kill the charge thinking the bank is full? When will the lagging batteries ever charge?
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During absorption. Inverter gets its "lithium" settings from the AGM settings entered in by the installer. Maybe as @SauRoNZA says and the new battery never reaches 100% and @Hanno Labuschagne hasn't checked the LED's on the batteries when the inverter says its full?
 
wingnut771 said:
During absorption. Inverter gets its "lithium" settings from the AGM settings entered in by the installer. Maybe as @SauRoNZA says and the new battery never reaches 100% and @Hanno Labuschagne hasn't checked the LED's on the batteries when the inverter says its full?
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Both batteries show five lights when at 100%, but that could be for anywhere between 80% and 100%. I am taking a multi-pronged approach here based on everyone's input:

- Deplete to minimum rated SoC
- Charge up to 100%, turn on Activate, and stay there for 24 hours
- Deplete again to minimum rated SoC and check battery lights and voltages throughout with multimeter
 
I would just go the multimeter way first instead of wasting hours to charge and discharge. Check voltages and after that you would see what needs to be done or if anything.
 
x7razor said:
I would just go the multimeter way first instead of wasting hours to charge and discharge. Check voltages and after that you would see what needs to be done or if anything.
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Voltages will be fine, its the SOC that needs re-calibrating. Maybe the new battery has never fully absorbed before due to inverter thinking its 100% from a BMS signal from the master? Has it always been like this @Hanno Labuschagne?

I would use the multimeter just to get an estimated SOC reading.
 
This is ultimately a non-issue that would fix itself over a few days/weeks as long as they reach 100% for extended periods.

But if it bothers OP enough then just force it and all the lights will flicker together and report singularity and all will be right with the world.
 
SauRoNZA said:
This is ultimately a non-issue that would fix itself over a few days/weeks as long as they reach 100% for extended periods.

But if it bothers OP enough then just force it and all the lights will flicker together and report singularity and all will be right with the world.
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Speak english man :P
 
SauRoNZA said:
This is ultimately a non-issue that would fix itself over a few days/weeks as long as they reach 100% for extended periods.

But if it bothers OP enough then just force it and all the lights will flicker together and report singularity and all will be right with the world.
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I asked and he said they typically stay at 100% for 2+ hours a day. So they should have synced their cycles by now and not be this difficult.
 
B-1 said:
I asked and he said they typically stay at 100% for 2+ hours a day. So they should have synced their cycles by now and not be this difficult.
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The new battery probably has different cells inside with a lower resistance. The old battery will catch up when the voltage differential widens.
 
B-1 said:
I asked and he said they typically stay at 100% for 2+ hours a day. So they should have synced their cycles by now and not be this difficult.
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A few hours didn’t do the job for me when I had the problem.

Suspect it’s a case of super slow trickle charging at the top end before it’s truly full.
 
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