Battery or Alternator Issue??

[CAMELLA]

Not sure if I have an issue or just never noticed it before but is it normal for the battery gauge to read 14v and then down to 12v and back up to 14v at idle? This is on my port side which is also the house batteries, the starboard batteries stayed at a constant 14v. The batteries were on a boat charger all winter. Does this sound like a battery or alternator problem, or is this normal.

 

[Molson]

my sea ray wouldn't kick in to 14v till it got bumped off idle. then it was fine. I was told its normal and its "supposed to do that".

Put a multimeter right on the lead from the alternator.

 

[SkippersList.com]

Have been on a few boats that the volt meters like to dance at idle ... never seemed to bother anything and everything always checked out ... always seemed to calm down after a bit or once you started running the engine.

I was told once it has something to do with the where the alternator kicks in and where the engine is idling ... sort of an indecisive where there;s not quite enough rpm for the alternator to kick in but the battery is at a level that would call for the alternator to kick in.

Doubt it's the battery unless there is a bad connection some where. Be sure there are no splices in your battery cables where the gremlins like to hide.

 

[Alex F]

Not sure if I have an issue or just never noticed it before but is it normal for the battery gauge to read 14v and then down to 12v and back up to 14v at idle? This is on my port side which is also the house batteries, the starboard batteries stayed at a constant 14v. The batteries were on a boat charger all winter. Does this sound like a battery or alternator problem, or is this normal.

Jon,

If these symptoms only during the times when the engines are colder than normal operating temp, then what you see is a normal operation. The reason why the voltage drops is b/c the grid heaters kick in. They run in cycles. The kick in, stay on for about 30 sec and turn off. This cycling continues on until the engines are warmed up. If you would fire up your cold engines at night you would see house lights go dim as well.

Now the fact that you only see it on the port side may indicate that your stbd side grid heaters don't function properly.

This is my preliminary opinion based on what you describe.

BTW, since this is something you just noticed and in case if you didn't know the cycling of the grid heaters, then you'll appreciate the following tip I've learned from my Cummins tech when I got my boat. The best way to fire up our Cummins engines is to hit the rocker switch on one side (either side), then watch the volt meter. Allow grid heaters to complete the first cycle (voltage drops to 11-12 and then comes back to 13-14), then as soon as the voltage comes back to normal fire up that side. This way you allow the engine to use maximum juice from the batteries. If you don't pay attention to this, then your batteries doing twice as much work, first they provide the juice for grid heaters and then you're hitting them with the engine start-up load.

I'm very conscious of this when I fire up my engines.

 

[kevin27]

This is normal. You should have inlet air heater grids and they consume lots of power. They cycle on and off at low RPM settings.(I think below 1000 RPM) I see you are in Florida so they are really not needed. If you like there is a fuse that can be pulled to deactivate the heaters. My B series engines have the heaters too and I am goings to pull the fuse as well. It is there to help keep the smell and smoke lower when the engine is cold.

 

[CAMELLA]

Thanks everyone for the comments, I didn't know about the grid heaters but It makes sense. I will watch the volts on the gauges the next time I'm out to see if it stops after the engines are warm.

Alex, not sure if the starboard engine was doing it, I thought it wasn't but maybe it was. I was just so focused on the port.

Thanks again guys.

 

[GrandMaster]

FYI, my gauges do the exact same thing and I have gas sterndrives. I haven't had any problems