Battery Charger seems to be shutting off

[goletamoby]

For my Cutwater C26, for the last few trips down to the boat (kept in the marina on shore power), I've noticed all batteries (engine, house, thruster) had a lower voltage of around 12.8V, even though after a cruise they are up in the mid 13's and 14+ when connected to shore power with battery charger engaged.

If I cycle the battery charger circuit, it kicks back on (I may be able to hear the fan?), and the voltage climbs back up to 14+ and holds there for a while.

Any ideas on how to further troubleshoot the charger or what might

 

[watson1987]

What is the age of the boat/batteries?

 

[goletamoby]

The boat is 2013, not sure about batteries. How do I check?

 

[watson1987]

The batteries might have a date stamp on them.

12.8V is effectively a charged battery without any load on it. When cruising and the alternator is running or on shore power, seeing voltages in the 13-14.5V range is expected.

It is also expected to see batteries drop to 12-12.2V when under load, or even lower depending on the amperage draw, if not on shore power and not running the alternator. If the batteries don't recover after the load is removed and drain quickly, you should consider replacing your batteries.

As a reference, here is an estimated charge remaining for batteries that don't have a load applied to them
https://learnmetrics.com/agm-battery-vo ... y-voltage/

Also - it is normal for the battery charger to shut off because it should detect a fully charged battery and then go into a trickle/top-off cycle where it goes on and off to keep the battery healthy. Batteries don't like to have charge applied to them once they are charged

 

[goletamoby]

Ah, ok. So what I’m seeing is just normal Behavior then?

Thanks for the battery level chart. That is super helpful.

 

[Just Right]

Check the inline fuse holders on each of the charge leads. Battery 1 House, Battery 2 Start, and battery 3 Thruster. I had the same thing happen to me and two of the holders needed replacing. Be sure to load test each battery. Voltage does not tell the complete story of battery condition. I would isolate each battery for this test. Your boat should have 2 ACRs . One between start and house and one between Start and thruster. If you have a bad battery in the system it can create an issue with the charger. Disclaimer, I know just enough to be dangerous. What happens is the charge voltage closes all ACRs basically putting everything parallel. The charger continues to try too fully charge bad battery while parallel to the others. I have replaced all batteries and everything behaves as it should. My batteries would maintain 12.8 for several days without load. They failed load test dropping to 8.5 volts under load. ACRs are closed if the green LED is on. If you don't see green LED and you have verified that you have a charge voltage check the ground wire going to the bottom of ACR. Most likely corroded and needs to be cleaned. Check your charge profile set on your charger. The charger will maintain a float charge around 13.2 volts . I never see any voltages below 13.2 when on shore power and charger on. Last thing. I just installed a Victron Smart shunt. In my opinion the 130.00 dollars I've spent in a while. Definitely something I would recommend.

Hope this helps

 

[goletamoby]

So the ACR that connects Thruster and Engine is not connected to the engine battery. That end is in fact not connected to anything. That ACR is flashing fast green.

The other is connected to house and engine and is solid green.

Also I couldn’t locate the inline fuses, but then again not sure what I’m looking for. Any ideas?