question

rechena avatar image
rechena asked

SOC Reset to 100%

I think I know what it is based on a quick internet search but wanted to double check if theres a way to fix it/prevent it.


TLDR; I have installed a Lithium battery with internal BMS that shutdown charge when temp bellow 0C. I then proceeded to turn on my engine and the DC/DC kicked in, but off course no charging was going in the battery, as you can see by the screenshot attached. But, because the voltage was above the 14V the Smartshunt assumed it was charged.. so now I have a partially discharged battery which was at 84% when I started the engine to a 100%(false)...


How do I present/fix this? Is it even fixable?


img-9718.pngThanks for the help

Lithium BatterySmartShuntSOC
img-9718.png (310.5 KiB)
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1 Answer
theo74 avatar image
theo74 answered ·

Als long as the BMS is locking it's battery, it's hard to change the situation towards the shunt.

When the BMS unlocked the battery again, I would expect an instant lower voltage towards the shunt, giving another SOC level then 100%. Did this not happen?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

@Theo74 please don't use the Victron logo as profile picture. Other users could think you are a official Victron employee.

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theo74 avatar image theo74 Matthias Lange - DE ♦ commented ·
No problem Matthias, done.
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pwfarnell avatar image pwfarnell commented ·
@Theo74 The SOC is based on Ah counting in and out of the battery not voltage so when the BMS restarts the SOC will stay at 100%.
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theo74 avatar image theo74 pwfarnell commented ·

Yes, you’ve got a point there, forgot about this one…


You could try to change the charging status in the shunt app back to 84%.
Go to settings - battery - state of charge. See manual page 11 4.3.3


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rechena avatar image rechena pwfarnell commented ·
Thanks for he reply. which is exactly the point.. the battery is not accepting any Ah. So from doing a bit more digging, ititss purely relying on the fact that the voltage is at X for Y amount of time so assumes the battery is at SOC 100%. So yeah I will need to go back and when the battery unlocks again (still cold here) I will need to measure voltage and according to specs calibrate the shunt...
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