Alternator Charging Question

[richardm6994]

Just wondering if anyone can cast any light onto this strange occurrence earlier;

 

Coming back from a drive out, on the last couple of straights before my house I gave the kit some welly. It revved high....but not really excessive (5-6k).

I looked over at the dash (always keep 1 eye on the temp gauge even though Ive not had any overheating for a couple of years now)....I noticed the volt meter had suddenly dropped to 10v.

 

Normally it's at 14.5v when no load is on the alternator, and 12.5-13 when at full load (water pump and fan going full blast.

 

I expected it to be a broken belt as revving the engine had no effect on the 10volts.

 

Not a broken belt, so I turned it off, let it cooled and fired it up again, this time voltage shot back up to normal.

 

This is the first time I've ever seen this happen, it's like the alternator suddenly stopped working (even though though the belt hadn't broke).

 

With blyton now booked and paid for, it's playing ony mind a little.....but at least it has prompted me to buy a spare belt 'just in case'

[Guest mower man]

Rich not exactly the same but I had recurent fault when some times [ not consistently ] but after a good run out the alternater light would flicker up to around 2/3500 rpm I think I found it whilst getting ready to deliver Flossie to her new owner ,by waggling the 2 big leads into the alt I could stop it charging or bring it back in ,I cleaned both connector s and gave the lucars a bit of a crimp with the pliers all seems good now so off she goes tommorrow HTH Mick

[richardm6994]

Cheers mick,

 

The alternator is 60amp and is one of these;

 

[sj-bradley]

If it happens again, see if you can feel how hot the alternator is.

 

If it's overheating, there may be a heat regulator which cuts in limiting the output voltage.

 

It could also be the voltage regulator inside with a heat related fault. They are 3 phase AC generators with a full wave rectifier and associated regulators which should provide your nominal charging voltage.

 

If it is faulty, it's going to be the regulator side as the windings will not likely be the problem. You should be able to recondition it by replacing just those bits.

 

Simon.

[speedtripledan]

Carbonised contacts me,s think

Edited September 21, 2014 by DanE

[richardm6994]

Went for another run out after tea and everything is normal once again and no voltage drops. Will keep an eye on it though!

 

Overheating could be a problem, everything in the engine bay around the engine gets that hot you can't touch it! Maybe look into a heat shield....

[Snapperpaul]

I fitted a heat shield to stop heat soak from the exhaust manifold and have a 30mm tube driving air to the rear of the alternator

The pulley/ fan draws air through the alternator from the rear

With the look of yours it draws air through the side casing

Edited September 22, 2014 by Snapperpaul

[fry61]

And at the other end -- what instruments are in the dash -- could be just a poor reading of a good alternator.

[bullfist]

Belt slip? I occasionally suffer a loss of a small amount of steering pump fluid (albeit no power steering) - and this is located by the belt. A good warm run usually dries it out.

-steve