Starter battery drawing down with house batt

[harleyman012358]

I live a board a 97 passage 42 and during an extended anchor my house batterys went down to 10 volts over night. What suprised me is the starter battery also was drawn down to a point where it would not start the gen set. I did get a jump to get the gen set started. Apon return to the marina I took out the starter battery and had it load tested to find It was in good shape. (It took a full charge)
My question is, where is the house batterys and the starter battery connected and why would the starter battery be getting the house battery draw ???
Anyone have this issue ??

 

[Bill Roosa]

bad cell in the house bank

A bad cell in one of the house bank batts would cause this IF they are connected. The shorted cell just sits there and sucks up current from everything including your start battery.
Course most of us isolate the starter batt for just that reason. I'm not acquainted with your set up. Do you have a 3-way switch or some automatic isolation means?

 

[Don12364]

I would have thought the starter battery was specifically reserved for starting the boat's main engine as a safety feature.
The last thing one would want is the gen set starter being able to deplete the engine start battery.
I guess it is working just as the designer intended.
If you want it otherwise then moving just one wire should do it - though the nuisance factor of having to jury rig a connection between batteries to get the gen set running might also act as a reminder not to flatten your house bank.

 

[Bill Roosa]

auto start genset

Perhaps the genset is sensing the house bat because it auto starts and recharges it.
perhaps one of those switches you don't use much is in the wrong position.