Thread: Alternator Volts?

The small wire is the exciter. A handy bonus is the charge lamp in the dash.
Aaron

I hate to contradict but for accuracy, the D2 alternator is self-excited type works on basis of self-excitation caused by the increasing magnetic field of the rotor after the engine was started, it has no separate "exciter"...those two thin wires in the plug are there for what was described in my last post

I am struggling to know what this thread is about.

It seems to me that Pedro's new alternator is fine.

When cold they output about 14.5 volts, when hot about 13.7-9.

The battery is not fully charged because he didn't drive long enough.

Regards Philip A

Originally Posted by Pedro_The_Swift

Mick---- the battery is about 12 months old

Yep. I've found K-Mart batteries don't last long too.

Originally Posted by sierrafery

I hate to contradict but for accuracy, the D2 alternator is self-excited type works on basis of self-excitation caused by the increasing magnetic field of the rotor after the engine was started, it has no separate "exciter"...those two thin wires in the plug are there for what was described in my last post

That is interesting. If it is self excited there could be significant voltage drop between the alternator and the battery, especially if the connections are not as clean as they could be.

A former workmate had a car that the alternator had a Vref connected closer to the battery. To maintain the 14.2V of the system, at times, the alternator was pumping out 16V.

Pedro, What is the voltage at the battery compared to the voltage at the alternator whilst running? What I am looking for is excessive voltage drop that may be caused by corroded connections.

Originally Posted by sierrafery

in a nutshell(cos it's not simple at all): the small plug connects two circuits, one is for short circuit protection(white/green wire) and the other for the warning lamp(brown/yellow wire)

A warning lamp operates in the exciter wire. Any alternator will self excite if it has enough residual magnetism to generate enough voltage to overcome the forward bias voltage of the exciter diodes.
Aaron.

Originally Posted by Pedro_The_Swift

All good info Jazzman,There are two part numbers for the D2,
The change is a different manufacturer.

This is the correct alternator.

but it would seem it hasnt solved the problem.

I misread the lower voltage. The 12.3V was across the battery with the car turned off I now assume. This is not too far wrong. I wouldn't be too concerned. Yes it could be better but it's not too bad. The only suggestion i have is to make sure all the connections are clean and firm. There is another trick you can play with any battery, if you put a digital voltmeter across the battery, in this case without the car running, have some load on it something simple like the interior light on. If the chemical reaction in the battery is working correctly you should see the voltage slightly decrease then slowly increase until it saturates. Maybe useless to you but still interesting to know and watch. Depending on how much cycling you've put your battery through batteries on average last about 3 years. If you bought a cheap / poor quality battery and how often you drain it before charging it is possible it would get close to the end of its life after 1 year. The standard size battery in a d2 seems to be pretty large you might need to charge it for a night on a charger to get it to come up. You could try driving for an hour but fuel is expensive. So is electricity for that matter. Lots of words, i hope some of them are useful.

bad earth.
bad earth.
bad earth.

car now running over 14V all the time