Volvo Penta 5 liter charging

[GregCom]

Multi part question….It’s probably a simple solution here goes as I’m a newbie. I bought a used boat. 96 Campion with a 5liter Volvo Penta. It seems to run extremely well. It does have a multi position switch at the batteries (2 batteries)
Which one should I be using? 1, 2 or All?

second part
The engine when turning over seems to be turning over slowly. Yesterday while out I noticed the voltage gauge was showing 11.5 volts. If I opened the boat up full speed I would have suspected the gauge to have increased. It didn’t. This leads me to believe I have a defective alternator. I’ve opened everything up as it’s a very easy to work on. I would like to start some basic trouble shooting as I have a little auto experience on old school engines. The larger post on the back of the alternator should be where voltage is coming from so if I place my meter on that post and ground the other probe I should be delivering over 12 volts.
Can anyone confirm all my questions? Please and thanks!!
Greg

 

[James L]

When I had that setup what I did was pick one battery as the engine start battery and one as the leisure one.
On startup go to 1.
Once running change to all to charge both batteries.
After shutting down the engine go to 2 so you don't drain battery 1 on leisure stuff.

You should be getting 13.6 volts when running, once the batteries have had a chance to charge up some bit.
So looks like either
1. dud batteries, but unlikely since they started the boat
2. dud alternator
3. wiring or switch problem.
4. dud gauge

First thing I would do is check the voltage on the batteries themselves and then check the voltage from the alternator as you say and then trace that wire to see where on the switch it goes, it's not unheard of for the switch to be wired wrongly by a previous owner.
You'll probably need a diagram of the alternator connections - but usually there will be a sensing line that will only turn the alternator on when a voltage is detected, if this is missing or wired strangely the alternator may not start charging.

 

[James L]

Assuming this was all working for the previous owner, I would try running with the battery switch in each position 1, 2, all and see if any position gives you a higher voltage.
If they had wired the switch incorrectly, it might be that it worked ok in the position they normally used.

 

[GregCom]

Okay thanks! I will look at the switch a little closer and follow your method. Additionally grab a voltage meter to see how the batteries are responding.