why is battery voltage rising too quickly?
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timselectric
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That's quite a jump. I'm guessing that the batteries are close to full. And not actually 71%.
timselectric
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Actually that doesn't make sense, either. With only 50a charging.
Can you access the BMS data? Maybe they are shutting off, due to a high cell.
That's what I thought(too fast).
I spent all yesterday charging at 20a to 100% so smartshunt is showing 100%. I discharged to 70% today via smart shunt so I believe it's accurate
MisterSandals
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What charger and what is the charge profile?
If you do not have a long absorb cycle, then your cells resting voltage may be near 3.35V (53.3V / 16 is 3.33Vpc so not far off that). So if you share your charge profile, a lot of that info will narrow down and explain what you are seeing.
What are your smart shunt settings? 3.33Vpc at rest (these voltage are measured at rest, right?) is higher Soc than 71% in most my batteries.
i can. its the jk bms and it doesnt log the data that I know of . Later today I will go to the shed and see if I can monitor in realtime. yesterday I was able to charge at 40a and Ive been charging at 35a from solar today but at 50a voltage just goes sky high.
ill have to write the charging profile and post it later.
i have the smart shunt(bmv 712 in my case) set to show full battery as 55.2v
timselectric
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Yes, need to monitor it as it's happening.
As others have said already, it is not uncommon for JK BMSes to report wildly inaccurate SOC readings especially for a regularly cycled pack. It keep drifting overtime. My JK BMS with 100 A, 0.6A balancer even has reported 65% at full charge in the past.
The JK does have a workaround feature that automatically sets the SOC to 95% each time the lowest Cell of the battery hits 3.5 V for LFP (56 V for 16S).
That is how the JK BMS tries to calibrate its SOC counter.
If this is not kicking in for you at the end of every full charge, then it is highly likely that your battery is not balanced or you're not hitting the required trigger voltage / cell.
I'm attaching a video showing how that 95% SOC jump looks for JK BMSes.
EDIT 30 JAN 2024: Somehow this SOC reset takes place only when balance switch is OFF. Which comes across as incredibly weird to me.
The JK does have a workaround feature that automatically sets the SOC to 95% each time the lowest Cell of the battery hits 3.5 V for LFP (56 V for 16S).
That is how the JK BMS tries to calibrate its SOC counter.
If this is not kicking in for you at the end of every full charge, then it is highly likely that your battery is not balanced or you're not hitting the required trigger voltage / cell.
I'm attaching a video showing how that 95% SOC jump looks for JK BMSes.
EDIT 30 JAN 2024: Somehow this SOC reset takes place only when balance switch is OFF. Which comes across as incredibly weird to me.
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Well a big dummy (ME!) Didn't see the continuous current charge setting in the jkbms and didn't realize it was set to 25a?
I was watching it as timselectric recommended and got a charge over current error even though voltage was good.
As you were ,guys ?
I was watching it as timselectric recommended and got a charge over current error even though voltage was good.
As you were ,guys ?
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timselectric
If I can do it, you can do it.
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Hey, we all do silly things. You are not alone in this.