Battery charger only charging Genet battery?

[Dark Horse]

Sorry if I was confusing. The charger is putting out 7v. The batteries are in the 10 to 11 volt range.

[km1125]

QR_BBPOST Sorry if I was confusing. The charger is putting out 7v. The batteries are in the 10 to 11 volt range.

And that goes to my comment that some chargers will not charge until they sense a "reasonable" voltage from the battery. I have two chargers in my garage like that. I have to hook up an "old school" (unregulated) charger to get the battery into a "normal" range before those more advanced chargers will take on the task and finish the battery completely/correctly. I'm not sure about your particular charger if it would do that or not.

[Dark Horse]

Batteries wernt at 7 that was what the charger appears to be putting out. Batteries were at 10-11 volts

[km1125]

10-11 volts is still very, very dead. Not low, but really dead.

[Dark Horse]

The batteries are only 2 weeks. Obvioudly something is draining them but the real issue is why instead the battery charger recharging them

[g36]

The batteries are only 2 weeks. Obvioudly something is draining them but the real issue is why instead the battery charger recharging them

Is the fridge is dc or the ac breaker is turned off causing it to run on dc then it will definitely deplete your batteries.

[Viper]

If you're checking charger output as you described, you won't get a true reading. If I read it right, you disconnected the batteries and took your readings at the charger output wires to see what the output voltage was. The problem in doing that with relatively recent chargers is that the charger has no battery reference voltage to determine what the output voltage should be.

With everything hooked up as it should be, turn your main battery switch off, turn your charger main breaker on and take voltage readings at each battery. With the main battery selector switch off, your two main battery banks will be isolated from each other, this won't allow a battery to influence voltage readings of the other. Depending on the charger and how long it's been on for, you should see a voltage anywhere from 12.8 to about 14.8 volts depending the charge cycle the charger is currently in. If it's in an equalization cycle, you'll see voltages around 15.5 volts. A reading much lower than 12.8 volts warrants further investigation but you have to approach it as a whole system and not be quick to condemn the charger because of low voltage readings, several things need to be checked first. The battery voltage you mentioned isn't low enough to prevent the charger from kicking in, so I suspect that's not the issue. I would start by ensuring all connections are clean, tight, and in good condition/properly made. This includes the connections at the charge breakers which will likely be at a remote location as bud described. Ensure the main negative cable connections away from the batteries are also clean and tight as this may make a difference on the output charges depending on where the charger ground is hooked up.

When you measured the generator battery, did you disconnect the charge wire and measure it that way or did you just measure at the battery with the wires in place?

Check out all the recommendations we made and let us know what you find so we can go from there.

[Dark Horse]

I did not measure the generator battery only used the source function on the charger to cycle thru the batteries i.e battery 1 - 1 red bar (low battery), battery 2 (genset) 3 yellow bars (battery at 80%) battery 3- 1 red bar (low battery) .
If the battery charger was in fact charging batteries 1 and 3 they would be showing yellow bars ( it has 4 yellow bars each one signifying a level of charge from 20% up to 100% )
When I went to the boat Friday I turned off the main battery switch so there is no longer any drain on batteries to see if they would recover.
I am heading there today and bringing a regular battery charger to recharge battery if needed.

[bud37]

I am curious as this may be important to this problem wondering whether it is in the original factory location or not as to where it was in my 2001 Mariner

Where is your charger mounted in your boat and can you take a pic of your panel where the battery switch and breakers are and post then we can help with the switches as they are.

[Dark Horse]

The battery charger is located where the original one was - it is on a compartment located under the seat at the table.
I will take a picture of the panel today. But I am atta hing a drawing of it from owners manual.