SOK 206AH DMOS issue

[CDN_Solar]

I have 3 x 206AH 12v SOK batteries connected in parallel to a Victron Power in buss bar. Using 4/0 cable of identical lengths to connect from each battery to the buss bar. This arrangement works well except when I turn on a high load RV air conditioner. Only one of the batteries will turn off DMOS. the other two remain on.
After a period of time the DMOS will turn itself back on again.
Curious to know if anyone else has had this issue? When I contacted SOK, they replied the battery needed to be charged.
Your thoughts would be appreciated.

 

[sunshine_eggo]

I have 3 x 206AH 12v SOK batteries connected in parallel to a Victron Power in buss bar. Using 4/0 cable of identical lengths to connect from each battery to the buss bar. This arrangement works well except when I turn on a high load RV air conditioner. Only one of the batteries will turn off DMOS. the other two remain on.
After a period of time the DMOS will turn itself back on again.
Curious to know if anyone else has had this issue? When I contacted SOK, they replied the battery needed to be charged.
Your thoughts would be appreciated.

If you're talking about a RV rooftop A/C, you may be looking at a momentary surge around 500A. This may trigger short circuit protection and disable the DMOS.

Have you actually used a torque wrench on all the connections?

Have you considered a soft start?

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These should reduce the peak surge by about 2/3.

 

[CDN_Solar]

Thanks for the reply. All connections were torqued. Lugs were cleaned before installation.
I was hoping to avoid a soft start (just one more thing in an already expensive system) but I think I may need to reconsider.

 

[sunshine_eggo]

Thanks for the reply. All connections were torqued. Lugs were cleaned before installation.
I was hoping to avoid a soft start (just one more thing in an already expensive system) but I think I may need to reconsider.

Have you tried shuffling batteries around? Would help isolate it of it's a position issue or if it's the battery itself.

 

[CDN_Solar]

I have not, but definitely worth a try. The problematic battery is currently in the center of the buss bar.