Vovlo D4 EVC system query

[Nick Wight]

Yesterday we had a problem develop which I am reasonably confident I have diagnosed to a failed, or failing house/domestic 12vdc lead acid battery. I say "reasonably" because one aspect of the symptoms does puzzle me.

When the output from the battery crashes because of trying to run something like the anchor windlass, the supply to the helm (including all instruments) is interrupted and the engine stalls. I am confused by that as I understood that the PCU and the HCU received a stabilised voltage supply directly from the engine. If that is so, then why does the helm supply failing cause the engine to stop? We do have the optional EVC System Display, if that makes any difference.

I am sure that someone will clear up my confusion.

Thanks! Nick.

 

[volvopaul]

Yesterday we had a problem develop which I am reasonably confident I have diagnosed to a failed, or failing house/domestic 12vdc lead acid battery. I say "reasonably" because one aspect of the symptoms does puzzle me.

When the output from the battery crashes because of trying to run something like the anchor windlass, the supply to the helm (including all instruments) is interrupted and the engine stalls. I am confused by that as I understood that the PCU and the HCU received a stabilised voltage supply directly from the engine. If that is so, then why does the helm supply failing cause the engine to stop? We do have the optional EVC System Display, if that makes any difference.

I am sure that someone will clear up my confusion.

Thanks! Nick.

Too much voltage drop , winch obviously powered from engine battery , I’d suspect battery is dying when you use winch causing evc voltage drop recognition

 

[Nick Wight]

Hello Paul & thanks for responding.

Yes, that's what I thought -- BUT -- I think the windlass is powered from the house/domestic battery, not the starter battery. I should explain that we live a 250mile, 5 our round trip from the boat (no overnight stay allowed) and so I had very little time yesterday to fully investigate.

I've sorted a new battery, but we will not be going down to the boat again until 3rd July, when I'll fit the new one and see what happens.

Am I correct in the way I think the PCU and HCU are powered?

 

[Nick Wight]

I have now confirmed that the anchor windlass is indeed powered from the house battery and not the starter battery, so I am confused as to how a failed house battery can cause the engine to shut down?????

It has been suggested that with the engine running when the windlass draws current the alternator would try to compensate for the failed battery and the EVC somehow senses that as a fault condition and shuts down the engine. Can that possibly be so?????

When it happened we did get an orange triangle warning and a CAUTION message with the ever useful CHECK ENGINE message.

 

[volvopaul]

I have now confirmed that the anchor windlass is indeed powered from the house battery and not the starter battery, so I am confused as to how a failed house battery can cause the engine to shut down?????

It has been suggested that with the engine running when the windlass draws current the alternator would try to compensate for the failed battery and the EVC somehow senses that as a fault condition and shuts down the engine. Can that possibly be so?????

When it happened we did get an orange triangle warning and a CAUTION message with the ever useful CHECK ENGINE message.

You just answered your own question .

 

[Mr Googler]

You’ve probably got a split charge relay or diode somewhere so your engines charge the house batteries when the engine is running.

thats how the engine alternator can “see” the drop I would imagine.