Domestic alternator doing my head in.........

[Bimbly1]

 

Would you like some Birch twigs.

 

 

I usually have to pay extra for the birch treatment

 

Having fully charged the bank via the landline, when the engine was started, I got the following readings from the correct cables:

 

Engine: 1600 rpm

Alternator: 15v, +ve 0.53amps, -ve 0.99amps

 

Battery bank: 15v, +ve 0.68amps, -ve 0.85amps.

 

A marine engine electrician of some repute suggested that the voltage may well be just within an acceptable range, providing the amps are low.

 

I don't want to but it may be prudent to demount the alternator again and have it checked in greater detail to see if these results can be replicated on a bench test.

[Tony Brooks]

Just a thought, how old is the battery in the multy-meter? Flat meter batteries can give all sorts of odd readings.

[Bimbly1]

Just a thought, how old is the battery in the multy-meter? Flat meter batteries can give all sorts of odd readings.

 

Thanks Tony. On that thought, I bought and fitted new batteries. Still getting odd readings.

15 volts from back of alternator and at bank. Have cross checked using three different meters with same result but only have one clamp meter.

 

At bank; range of 1.14 to 2.16 amps on neg cable; -0.5 to 0.46 amps on pos cable

At alternator; 0.20 amps on neg cable; -0.14 amps on pos cable

at the alternator, when I read the pos cable, no matter which way round I clamped it, I got a negative reading.

 

Considering getting a sparks to look things over and/or taking the alternator off and letting Ken Cox & Co have a play with it.

[George94]

 

One should not allow 15V on a sealed battery, particularly some AGMs, for any length of time.

 

Experts may counter this opinion. If they do, then I will share their opinion.

 

The conditioning charge for a Lifeline AGM battery is 15.5V for eight hours.

[Theo]

Whilst I can believe there is a self limiting phenomenon relating to current induced back into the stator, the primary means of regulating the alternator is by means of the regulator! If the voltage rises above the regulated value, the regulator should reduce the current in the stator thus reducing the current and hence the voltage output.

 

Certainly in the old days of electromechanical regulators (on dynamos and some aviation alternators) you could hit a low rpm where the regulator contacts remained closed and the output was a little higher than if you increased the rpm and the regulator contacts started switching, but I wouldn't have thought that should happen with an electronic regulator. Maybe Snibbs will put us out of our misery!

Looks as if you have your stators and rotors mixed up. The regulator controls current to the rotor. It is this rotor that gives the rotating magnetic field which induces the emf (voltage) in the stator coils. The stator coils are connected to the load via the rectifying diodes.

 

N

[nicknorman]

Looks as if you have your stators and rotors mixed up. The regulator controls current to the rotor. It is this rotor that gives the rotating magnetic field which induces the emf (voltage) in the stator coils. The stator coils are connected to the load via the rectifying diodes.

 

N

Yes I know that, unfortunately my fingers don't!

[Arthur Brown]

Dynamos fed the exciting voltage into the Field winding and got the power out through the armature (via brushes). Two and three coil regulators had hysteresis but the power from a dynamo was never excessive.

 

Modern alternators feed the exitation to the brushes for the rotor and get the power out from the stator via rectifiers.