Alternator Wire - Help

[Wandering Star]

Just received an email from the skipper of my boat (a forumite) which has arrived in Bermuda today en-route to Portugal. He has listed a couple of problems including .....

".... the alternator does not appear to charge the batteries totally - there is a loose wire coming from the alternator that reads 12 volts - was this always like this? The wire is cut and there is no obvious place for it to go...."

Engine is a Volvo Penta 2003 of 1989 vintage and I imagine the alternator will be the standard one for that engine. The fact he says the wire reads 12 volts, would seem to suggest to me that's the wire which should be connected to the batteries in order to charge them?

Anyone got any ideas? I'd like to get back to him today or tomorrow with suggestions, there's a multimeter on board so he could take some readings. If I can't come up with anything before Monday, I'll tell him to get an engineer on board but Bermudas a pricey place so ..........

Cheers, Brian.

 

[Richard10002]

What kind of boat? Is there an Owners Association/web site, that may be able to identify the probable make/model of alternator?

No expert but if the batteries are charging at all, it doesnt sound like it can be the wire to the batteries.

Have you got a photo of the back of your alternator, and can he describe where it actually comes from on the back of the alternator? The make/model may also be marked on the alternator. Mine is a Valeo and I think it is about 55A

This is a pic of the back of mine on a VP MD22L

The yellow wire is voltage sensing from the regulator, The thick red is the positive, the thin red I dont know what it does, the brown is D61 which goes to the engine control panel, the grey is W which goes to the engine control panel and drives the tacho and there is a thick black connected bottom right of the pic which is the negative.

I think these cover most wires out of most alternators, but I'm sure someone more knowledgable will be along soon.

Good Luck

Richard

 

[halcyon]

[ QUOTE ]

".... the alternator does not appear to charge the batteries totally - there is a loose wire coming from the alternator that reads 12 volts - was this always like this? The wire is cut and there is no obvious place for it to go...."

[/ QUOTE ]

You need to expand on

.... the alternator does not appear to charge the batteries totally, what is totally ?

..... there is a loose wire coming from the alternator that reads 12 volts, what size is the wire, is the 12 volt there all the time, or only when engine running.

Brian

 

[VicS]

The wiring diagram is in (some of ) the owners manuals which you can download from HERE

However the wires from the back of the alternator are

A heavy (10mm²) red wire carrying the output to terminal 30 on the starter motor solenoid

A brown wire (1.5mm² ??) from connection 61 to pin 5 of the multi-way connector and ultimately to the warning light on the panel

A grey wire from terminal W via connection 13 of the multi-way connector to the rev counter

And black wires which go from D- to a relay and either directly to earth or to earth via an earthing relay on some versions

 

[boatmike]

Correct entirely apart from the colours which may vary. It is also totally possible that the alternator has been wired for a smart regulator which has subsequently been removed. If this is the case the wire will dissapear into the back of the alternator without being connected to an external terminal. Ask him what colour the wire is and what terminal it is attached to. If the alternator is charging at all and the light goes out on start up it is probably OK and this wire is probably a smart regulator wire which is redundant. If the batteries are not reaching full charge it's more likely tired old batteries. Alternators tend to work or not. There aren't usually half measures unless it's internal regulator has blown which usually shows over voltage.

 

[morgandlm]

Since there is a multimeter on board I suggest you get the skipper to measure the voltage across the battery(ies) when the engine is running and when it is not. This way he will, at least, find out whether the alternator is charging or not. Without a smart regulator of some sort he should find around 13.8 volts when charging. If significantly less than this there is a problem. If 13.8 volts or thereabouts then perhaps the batteries are clapped or perhaps there is an excessive power drain.
Morgan

 

[Wandering Star]

Just a quick thank you for all the advice which I've passed on to the skipper.

Very slightly off thread, but none of the explanations identify how the actual batteries receive their charge. As described, none of the wires actually physically connect to the batteries? Does the thick red wire which it's been identified should be connected to the starter solenoid, eventually end up (by a circuitous route) connected to the batteries too?

The skipper isn't asking me for this information, this is a question for me! If I had the boat here I could work out the answer but as I don't, I thought I'd ask, which is the wire that physically charges the battery!

Cheers, Brian.

 

[Heckler]

F
the thick red wire that you can see in richards pic goes to the starter motor, then a thick wire goes from there to the battery switch and then from the other side of the battery switch to the battery, similarly the black wire goes the same route.
the w is for the rev counter and the d is for the warning light as others have said.
Stu

 

[Wandering Star]

Thanks Stuart, that's very clear!

Thanks everyone! I understand my boat just a little bit better now!

Cheers, Brian.