Dead Starter Batteries when Gen Set Running?

ALLFORARI

Had her out this weekend at the beach and ran AC and DC on with Gen Set running.  Went to start after 5-6 hours and had nothing at 1st then got one to fire on Emergency but not the 2nd.  Waited 10-15 min and then second started. Assume engine 1 charged batteries enough for Battery to fire engine 2?  Shouldn't Gen set charge batteries when its on if switch for Bat Charger is on in control panel?  Any ideas on fix so it doesn't happen again?  Never had a problem when boat is on shore power. Thanks

Stodge

The genny will charge the batteries if you have the battery charger turned on at the power panel.  

ALLFORARI

Both were in the on position. 

Stodge

When you get a chance, start the genny then watch the DC voltage when you turn on the battery charger.  It should go up a bit.

ALLFORARI

Thanks Stodge.  DC voltage on the Battery charger or DC voltage on main panel?

Stodge

Guess the first question I should ask is: Does the battery charger work on shore power?

Main panel should show an increase.  I want to say the battery charger shows amps, not volts.  But that's my charger.

If you don't see an increase in volts you have have an issue with your battery charger.

ALLFORARI

 I swapped out both starter battery since the Previous owner had not replaced him in five years. I thought that fixed the problem as she started right up yesterday. Went down today and the issue is back. I wonder if it’s the isolator as the charger seems to be working?

ALLFORARI

 Good news. I jumped on the boat yesterday and it wouldn’t turn over While on the hook. Why is that good news you ask? Because that told me that the batteries were not taking a charge, I replaced them and now all is good. Come to find out the previous owner had replace those batteries in nearly 5 years 

Handymans342

Is the isolator original?

jhofmann

Used to have a cuddy cabin with a single battery and got in the habit of bringing a charged jump-pak with me, and still do today even though I have a seperate starting and deepcycle house battery. Better to have it and not need it, than to need it and not have it!

ALLFORARI

Yes original I believe. 

zaverin1

You check for actual voltage going into your batteries either from the shore or gen?
it would be coming out of the battery charger either way
what I am saying is new batteries are just that new.
they have a charge and new cells 
if your charger dosent work you will soon be facing the same problem.
only charge you get is when your boat is running if your charger is dead

ALLFORARI

Hey guys. Sorry for the delayed response. It turned out it was a selenoid. Cheap fix. Thanks for all the advice