4.3 mercruiser alternator help

[Ian MacAulay]

Evening.

When I start my boat for the first time for a few weeks my battery voltage when engine is running is just over 12.3v . battery is new but after 10+ mins of running it slowly creaps up to 14.1v. Or if I rev the engine it creaps up too. Is this normal or have I a issue. It seams the alternator is unable to supply voltage / charge at idle RPM

Thanks Ian

 

[Danfarry]

Ian, pretty sure this is totally normal. My voltage is similar, 14v 'ish' when the engine is running

 

[bluejasper2]

hi ian, totally normal 14.1 volt is what the alternater is putting into the battery:encouragement:

 

[Ian MacAulay]

Thanks.


My query is that once engine is started it don't get up to this for 10mins ish... once started it sits at 12.3 is for a while unless rpm is increased


Thanks

ian

 

[James L]

yeah, that's normal, the batteries are obviously low enough that it takes some charging before the voltage can get up to 14.1.
I think the alternators pump out very few amps at tick over, when the revs get up then they start working properly.

As long as you don't hear the belts slipping then I think it's fine.

 

[Beamishken]

you may need to blip the throttle to get the alternator spinning fast enough to start charging once they are "Excited" they should charge at idle

 

[Ian MacAulay]

Thanks everyone that puts my mind at rest.


Thanks


Ian

 

[lynall]

My penta 4.3 starts charging at 14.5 volts from the off, which is what any alternator should be doing, regardless of the battery voltage.
Got volt gauges in both my old land rovers they are both the same, but they both need the initial blip as mentioned above.