No DC power

JoeWhite · Aug 4, 2014

What is voltage at the house battery switch? That is the feed to the house.

centerline · Aug 4, 2014

JohnnyMac said:
Tonight I took out my house battery to exchange it in the morning for a new one. I turned off the house battery switch, left starter battery on and turned on the shore power. After a couple of hours, I lost DC power completely. What do I need to look for? The battery shows 12.5 volts with a multimeter.

when you say you lost "DC power completely", does this mean you cant start the engine also or that you only lost power and dont have DC lighting in the house/cabin?....

the start battery should be seperated from the house, so removing the house batt will kill the house circuit, UNLESS you either have the battery switch turned to "combine" or you have a converter or charger working on AC power and converting the AC to DC...

look for a loose ground.... and im assuming you do have an converter/charger so its very possible you blew a fuse for the converter/charger...

you should have more than 12.5 volts at the battery if the converter/charger is working....

it kinda tough to tell you where to look without knowing what components you actually have installed....

Benny17441 · Aug 5, 2014

Could not get a clear picture of your setup or the details of the occurrence but will take a stab at one possibility. Assuming your starter battery is of the "starting" type and perhaps older than 3-4 years it is not too far fetched that it could have failed under the stress of being deeply discharged. Starter batteries have thin lead plates and are designed to deliver strong but short bursts of power. They do not take kindly to being deeply discharged and thus are not recommended for use as house battery. The voltage of 12.5V indicates about a 75% state of charge in a healthy battery but voltage alone cannot certify the battery is healthy. You may need to subject that battery to a load test. Since our small auxiliary diesels can be easily started by a deep cycle battery I have always recommended that one be used in place of a starter battery. They provide the backup to be used as house batteries in cases like yours. If after a load test the battery proves to be good then check for a clean and tight ground connection or a burnt fuse.

Bill Roosa · Aug 5, 2014

You can't have a 12.5 volt battery and have "completely lost DC power"
what does not work? What gets turned on when you "turn on shore power"? hopefully the battery charger.
we need a lot more specifics if we are going to be doing more than guessing.
if your "inverter" an inverter/charger?

Saillife · Aug 5, 2014

Could the breaker be bad?? That would kill your DC power. Seems to me the thing to do is see if you have DC power coming into the panel and than work your way back or forward from there.

Brian

Bill Roosa · Aug 5, 2014

But you had DC power after you removed the house battery?
Assuming (I know!) that your starter bat is isolated that would mean that the battery charger was powering the boat after you removed the house battery. It probably gave up after a while trying to charge an open circuit. Before you panic put the new house battery back in and see what happens.

Stu Jackson · Aug 5, 2014

Glad to hear that.

I'd add: someday you need to do a wiring diagram.