Alternator showing 11.43 volts

[john m]

My volvo alternator is showing 11.43 volts when the engine is Running at 1500 rpm is there something I could do to fix it or should I take it for a repair the belt is tight ans all connections look good

 

[VicS]

My volvo alternator is showing 11.43 volts when the engine is Running at 1500 rpm is there something I could do to fix it or should I take it for a repair the belt is tight ans all connections look good

It may just need a new regulator but the sensible thing to do is to have it properly tested and overhauled by a repair shop.

 

[billcowan]

Check for bad connections before you spend money.

New wires, tinned ones, and new connectors much cheaper than new alternators.

 

[john_morris_uk]

Overhaul at Auto Electrical shop is much cheaper than new alternator too!

 

[NorthUp]

What's happening at the charge warning light?

 

[coopec]

There must be a lot of experts on this thread who have the knowledge to advise.

My question is how did you test it to get 11.43? How good is your battery? Did you test that without the motor running?

I have no idea of your expertise in this area so I hope you don't mind me giving you this link.
https://www.youtube.com/watch?v=Bzz7P3qNHcE

 

[Bav34]

It's fair to say that I know very little about elektrickery. So perhaps I should stop now

Just an observation then.

When I start my engine I often have to blip the throttle as the charging warning buzzer sounds.

Apparently this 'excites' (???) the alternator and all is then ok.

Sounds like we might be talking about different things as your engine is at 1500 rpm and mine at about 850, but just a thought.

 

[boatmike]

Does the voltage increase if when you first start the engine you increase revs to 2500?
Are you checking the voltage at the alternator terminals?
If you are checking by looking at the engine panel voltmeter it should show higher than this without the engine running at all which would indicate no charge at all and a deeply discharged battery..... Is the ignition light going out? Does the battery struggle to turn the engine over at start?
If you are checking at terminals and volts don't increase at higher revs best you take it to an auto electrical repair shop as others have said. Its probably just the regulator. On the other hand if it's not charging at all they can still check it out for you at a fraction of the cost of a new alternator.

 

[PCUK]

Clean the terminals on the back of the alternator before doing anything else.

 

[coopec]

Clean the terminals on the back of the alternator before doing anything else.

Agree 100%

But I would like to know what the battery voltage is without the motor/alternator running

 

[john m]

I will try these things at the weekend

 

[Spi D]

If you take it to an workshop do tell them it is used on a boat as requirements (and certifications) are different between car and marine parts.

 

[johnphilip]

Check the voltmeter. Try it on the car or someone else's boat.I thought a second meter would be handy and bought a cheapie for 5 or 6 quid and found it to be miles out. Low battery in the meter can also cause inaccuracy.

 

[charles_reed]

Check the voltmeter. Try it on the car or someone else's boat.I thought a second meter would be handy and bought a cheapie for 5 or 6 quid and found it to be miles out. Low battery in the meter can also cause inaccuracy.

I'd suspect the voltmeter reading - or you'd already be complaining that the starter won't work.

If it's an external one change the 9v battery inside and try again. If not buy and external one from Maplins (or Amazon) and check volts at battery terminals with engine running and without engine running, these should be respectively between 13.5 - 15.1v (running) and 12.4 - 13.5 (engine off).

Meanwhile ignore all the well-intentioned advice on this thread - you'll possibly do more harm than good, especially as a self-confessed tyro.

If the reading are wildly away from this, I'd take the alternator off and away to an auto-electrician to check and repair. It should (for a diode-bridge repair) cost about £25. Don't buy a new alternator, avoid any companies with "marine" in their blurb or you'll treble your costs.

Bonne chance.

 

[boatmike]

Spi D

Perhaps you would care to expand on this statement and tell us what the difference actually is ????

 

[charles_reed]

Spi D

Perhaps you would care to expand on this statement and tell us what the difference actually is ????

Many marine alternators are double-insulated, especially on narrow boats. Don't know about Danish regulations, but most boats in UK use normal return (and suffer from occasional galvanic attacks). Usually true marine alternators have ss bearings and insulated earth return as well as allegedly different lacquer on the windings - this justifies (in their eyes) the eye-watering cost. The only reasonably priced marine alternator I came across was the 90 amp Lucas version through Adverc - I believe it's since been discontinued.

 

[halcyon]

Rectifier diode failed.

Brian

 

[Spi D]

Not talking Danish regulations in particualr since EU regs. rule (+some national additions for inland etc.) and I'm well aware that Danish doesn't mean a lot to fellow boaters in the UK

The main difference between a Marine Alternator and a standard alternator is in the ignition protection. Most marine engines are found in a compartment that is enclosed and have very little air flow. With these enclosed areas the gas fumes can easily and quickly build up and create an ideal situation for the fumes to be ignited. An alternator can in fact create a spark and ignite the fumes which is what a marine alternator is designed Not to do! Marine Alternators are built to meet or exceed CSA, USCG, ISO, CE & SAE Ignition Protection Standards. They are designed to eliminate sparks that can ignite built up fumes.

Besides the above, alternators for boat use often are selected/designed for the constant (low-ish) rpm running, longer wire run, multi battery bank setup and different equipment found on boats.

I find it wise to inform a workshop who rebuild your alternator (or anything) about your intended use. Sort of eliminating problems when the supplier knows what the customer expect :encouragement:

 

[Jim@sea]

Dont do what I did.
On the boat I have just bought (1984) both the Starter Motor and Alternator appeared to be the original Lucas and not wanting to go to sea with old equipment I asked the Yacht Broker I was dealing with if he could arrange to have them both "overhauled"
Starter done OK but there was a problem with the Alternator as they said they could not overhaul it. (I now know that other firms could repair/overhaul it)
So they sold me a New Modern Alternator.
The only trouble is that the old alternator had an external Regulator (lucas) and the new one has a regulator inside it.
The snag is the wiring for the old one (through the regulator) is completely different and the new one "by-passes" it.
And I am having to get an Auto-Electrician at £40 an hour (which I dont mind paying but the nearest one is 30 miles away)
The Boatyard where my boat is does simple 12v Electrics but they dont know how to do it.
So if you are goung to change your alternator, do research first.

 

[charles_reed]

Rectifier diode failed.

Brian

Possibly, but we don't know how valid the 11.34v really might be. Though, usually, with a failing internal voltmeter battery they read high rather than low.