Another top balance, real quick question.

[Gould]

Thought I’d check in, another 12 hours of charging today and the power supply is up 1 millivolt.

Question, will this slow and steady voltage climb continue to 3.65 or at some point does the voltage ramp up? I can’t imaging a single mv every 12 hours!

 

[Gazoo]

I am attaching a graph that might help you. As I recall my cells didn't start to ramp up until the voltage was 3.4 volts measured at the cell. From there the voltage ramps up quickly.

 

[Gould]

Thanks, appreciate it.

 

[Gould]

Day 7, slow but steady.

When I started the process I was focused on the capacity of the eventual batteries, not the individual cells. Am I right in thinking that we are trying to charge the total of all 8 cells I.e. 272 ah * 8 for a total of 2176 ah? If that’s the case I’m relieved. At 10 hours a day for 7 days now we’d be well above the 540ah of the eventual battery.

So, if they came roughly 50% SOC or 1088ah I’m looking at 9 or 10 days.

 

[GSXR1000]

Day 7, slow but steady.

When I started the process I was focused on the capacity of the eventual batteries, not the individual cells. Am I right in thinking that we are trying to charge the total of all 8 cells I.e. 272 ah * 8 for a total of 2176 ah? If that’s the case I’m relieved. At 10 hours a day for 7 days now we’d be well above the 540ah of the eventual battery.

So, if they came roughly 50% SOC or 1088ah I’m looking at 9 or 10 days.

yep

 

[Gazoo]

Day 7, slow but steady.

When I started the process I was focused on the capacity of the eventual batteries, not the individual cells. Am I right in thinking that we are trying to charge the total of all 8 cells I.e. 272 ah * 8 for a total of 2176 ah? If that’s the case I’m relieved. At 10 hours a day for 7 days now we’d be well above the 540ah of the eventual battery.

So, if they came roughly 50% SOC or 1088ah I’m looking at 9 or 10 days.

It took me 4+ days to parallel top balance my eight 280ah cells. I was using a 12 amp power supply and let it run continuously.

What are the cells voltage now?

 

[Gould]

I’m too paranoid to run it when I’m not at home or awake. Averaging 10-12 hours per day.

 

[GSXR1000]

let mine run 24/7 work asleep... home staring at it lol

 

[Gazoo]

I’m too paranoid to run it when I’m not at home or awake. Averaging 10-12 hours per day.

Getting closer...lol

 

[Gould]

Lol, crazy!

 

[Gould]

So finally at a point where voltage was increase and amperage dropping much quicker. I’ve been sitting here for about 30 minutes now, should I want for 0 amps or call it done? Is it possible that the power supply isn’t accurately putting out 3.65 V and it’s not able to fully saturate the cells?

 

[LED]

Just curious, how many hours did it take total?

 

[Gould]

Roughly 120 hours to get to this point. But something tells me I’m not quite done yet. May elect to just let the BMS complete the balance.

 

[LED]

So it looks like your batteries came to you with about 45% SoC.
I probably have another month before my batteries come in for my new pack. But I'm planning on charging them most the way as a bank (16S1P), then switch over to 16P for top balancing. Hopefully avoiding the time issues you had. I have an AIM 48 volt charger that'll get them there a lot faster than the low voltage 10 amp bench charger that I have.

 

[Gazoo]

So finally at a point where voltage was increase and amperage dropping much quicker. I’ve been sitting here for about 30 minutes now, should I want for 0 amps or call it done? Is it possible that the power supply isn’t accurately putting out 3.65 V and it’s not able to fully saturate the cells?

Your power supply and meter displays 3.63 volts with 250ma's still going into the cells. At this point there is negigable voltage drop so your PS is most likely accurate. It's up to you if you want to wait for zero amps but at this point the voltage should rise fairly quickly as the amps drop to zero. The voltage rise would be more evident if you had a 3 decimal place meter.

 

[Gould]

Appreciate the wisdom. I’ll turn things back on for another hour and see where it goes. It was hovering at .25 then fluctuating up to .50 and back down again.

 

[Gazoo]

Appreciate the wisdom. I’ll turn things back on for another hour and see where it goes. It was hovering at .25 then fluctuating up to .50 and back down again.

If you don't see any change after an hour then I would say your're done...

 

[John Frum]

I would call it done.
3.63 as measured at the battery terminals is more than close enough.

 

[Gould]

I’ll take that for the win.

 

[John Frum]

I’ll take that for the win.

You are measuring at the battery terminals, confirm?