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Rob Laubscher avatar image
Rob Laubscher asked

BYD 13.8 BMS setting DCL to zero at 100% SOC (sometimes)

Hello,

I have an EasySolar 48/5000/70 MPPT 150/100 Color Control with BYD B-Box Pro 13.8. Worked without issue for almost three years, then starting last December would sometimes turn off for a few seconds at a time when the mains was lost. I'm in South Africa and loosing mains during 'load shedding' is becoming more common the last little while. It only happened when the SOC was already 100%.

Looking at the VRM VE.Bus State I could see 'Off' state and also BMS DCL being set to zero. I have seen in the DVCC documentation that turning off is the expected response when the BMS sets the DCL to zero, when in inverting mode.

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It occurs when the load is small and substantial - doesn't seem to make a difference.

I tried setting ESS to 'Keep batteries charged' and the issue does not occur and seems to 'fix' it for a while when returning to the optimised ESS mode. I would of course like to actually use the battery during the night etc to use the least mains supply.

Is the BMS setting the DCL to zero indicating a problem with the battery? There are no warnings or errors being recorded anywhere that I can see, other than the DCL being set to zero.

Is there perhaps a BYD expert who could advise?

Thank you,

Rob

BMSBYD
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1 Answer
ejrossouw avatar image
ejrossouw answered ·

What is the SOC and voltage of the batteries when this happens? Also, what settings are you using for cutoff, sustain etc? If you did not already, maybe worth doing a full health check on all the power and data connections.

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Rob Laubscher avatar image Rob Laubscher commented ·

The SOC is 100% and voltage around 55V. The BYD's BMS manages the charging cycle - the inverter and solar charger just do what they're told.


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