Low voltage on leisure batteries while running alternator?

[Tasemu]

Turned the motor on and left the keys fully on so the light was on, after some revving the light turned off and after a small cruise my leisure batteries have gone from 12.7 to 13. So i'm thinking I just had the keys turned off while running the engine previously. *facepalm*

[nicknorman]

37 minutes ago, Tasemu said:

Turned the motor on and left the keys fully on so the light was on, after some revving the light turned off and after a small cruise my leisure batteries have gone from 12.7 to 13. So i'm thinking I just had the keys turned off while running the engine previously. *facepalm*

Yes it sounds as though your alternator is a bit reluctant to get going, so the scenario would be that you started the engine without enough revs to get the alternator going, and straight away switched the ignition off meaning there was no chance of the alternator ever getting going.

 

If you are having to rev the engine a lot to get the alternator working it might point to a partially faulty alternator, but probably best to see how it goes for the time being.

[MtB]

42 minutes ago, nicknorman said:

If you are having to rev the engine a lot to get the alternator working it might point to a partially faulty alternator,

 

Or just as likely, a really loose vee belt. 

 

 

[Tasemu]

Barely had to rev at all to be honest, just had to leave the light on.

[Alan de Enfield]

1 minute ago, Tasemu said:

Barely had to rev at all to be honest, just had to leave the light on.

Do you mean that 'normally' once the engine is turning over you switch the ignition off ?

[Tasemu]

1 minute ago, Alan de Enfield said:

Do you mean that 'normally' once the engine is turning over you switch the ignition off ?

Yup, well for the last 2 trips or so.

[Alan de Enfield]

1 minute ago, Tasemu said:

Yup, well for the last 2 trips or so.

Did someone suggest that this was the correct thing to do ?

I'm just wondering what you thought would happen.

 

 

[MtB]

7 minutes ago, Tasemu said:

Yup, well for the last 2 trips or so.

 

I’m mystified too. What promoted you to start turning the ignition back off after starting the engine? Have you ever driven a car? 

 

 

[nicknorman]

18 minutes ago, Mike the Boilerman said:

 

I’m mystified too. What promoted you to start turning the ignition back off after starting the engine? Have you ever driven a car? 

 

 

So cruel! Anyway the difference is that when you turn the key off in a car, it stops. Which is a clue.

[MtB]

36 minutes ago, nicknorman said:

So cruel! Anyway the difference is that when you turn the key off in a car, it stops. Which is a clue.

 

Not at all! There are plenty of youngsters out there electing never to learn to drive, preferring to use public transport and Uber taxis. If the OP has never driven a car how would he know the ignition switch stays ON after the engine starts? Instinctively, I think a non-driver would be tempted to turn the key OFF again once it has done its job of starting the motor, particularly given as you point out, it carries on running.

 

 

 

 

[Tasemu]

Never rode a car, only motorcycles. But yeah, i'm not sure why i turned it off, maybe assumed it was fine sine the boat was still running. But yeah definitely not my finest moment.

[MtB]

2 minutes ago, Tasemu said:

Never rode a car, only motorcycles. But yeah, i'm not sure why i turned it off, maybe assumed it was fine sine the boat was still running. But yeah definitely not my finest moment.

 

Even so, it is pleasing to get to the bottom of it and find such a simple solution!

 

 

[MtB]

And in particular, well done for properly answering the questions asked in the thread. This revealed what was going wrong.  AND for fessing up it was 'user error'! Thank you.

 

Lots of people posting here asking for help seem to think answering the questions is optional, and simply can't be bothered. Similarly with coming back and saying what the fix was, once found. 

 

 

 

 

[Tasemu]

All good, glad I got it all working and thanks for all the help. Still gonna run through the other checks on here just to make sure its all running the best it can be.

[Tony Brooks]

If a boat has any engine instruments or warning lights for things like oil pressure & overheat they will not work with the ignition turned off - neither will the charge light as you have found.