200amp Bus fuse blown

[markzorad]

Got to the boat (2021 C30S) last weekend to find the shore power breaker off and drained house/starter batteries.
We typically leave 2 low power convection heaters and both refers running.

After charging starter battery with portable charger and starting/running engine, each time we turned the engine or shore power off after about 30 seconds all house shut down (electronics etc.)
Crawled in to house bank and found the 200 amp inverter bus fuse blown.

All batteries are full charge when tested but not isolated from each other.
Any ideas as to why?

 

[Full_O_Fish]

30 seconds is the amount of time that the ACR (automatic charging relay) remains active. So if you were on shore power or had the engine running (alternator charging) the ACR would be active and supply power from the starting, thruster, and/or generator batteries to the house circuit. If you stopped charging it shut the motor down then everything on the house would stay on until the ACR cuts power access from those other batteries.

Your house battery bank is still in a low voltage state.

 

[markzorad]

Okay thanks Full_O_Fish.
Kind of my suspicion and I appreciate the input.
I will do a load test on each of the house bank batteries when I get back to the boat.
They had been run down prior at the dealer during warranty work, so me thinks one or more may be bad.

 

[markzorad]

I forgot to add that I still do not know how or why the inverter 200amp fuse blew?
Could the low or bad batteries be the culprit?
Good mechanic but not so much on electrical side.

 

[Red Raven]

I forgot to add that I still do not know how or why the inverter 200amp fuse blew?
Could the low or bad batteries be the culprit?
Good mechanic but not so much on electrical side.

There could have been too many loads running for the inverter to handle. Also, as the battery voltage goes down the current goes up in order to provide the same power output. I suspect the current eventually went over 200amps and blew the inverter fuse.

Curt

 

[Dcsqatar]

You mention your plan to "do a load test on each of the house bank batteries". It is my understanding that a normal ("carbon pile") load test(like you would do on a car battery) only works in determining the health of high cranking amp (starting) batteries. Our house batteries are deep cycle batteries which require a "C20" (or similar) test to determine their health. This test measures the ability of the battery to deliver power (Amp-hours) over a given time period (20 hours) without voltage falling below 10.5v. I know little about electrical systems, but I watched videos available from Pacific Yacht Systems and I got a bit smarter.

 

[markzorad]

Thanks for the replies and information.
I guess I have a little studying to do on the system to understand it a bit better.

 

[markzorad]

Have another question someone might be able to answer.
Does anyone know the size of the bolts/holes on the L3 type terminals for the stock UB Universal batteries that come with the boats?
Mine is 3 hours away and want to be sure I do not have to make up or get new cables with a starter & thruster battery replacement.
Thanks