Alternator down.....

**feral** · 17th February 2007, 12:56 PM

My alternator appears not to be charging the battery as good as it should.

I have started the Td5 and put a multimeter across and it is showing 13.2 - 13.5v at idle.

Is this normal?

According to specs I thought the alternator on these charge at 14.8v. The battery has a warning label to say do not charge above 14.8v.

Is it on the way out and can they be rebuilt?

Cheers.

**JDNSW** · 17th February 2007, 01:20 PM

13.2 is a bit low, even at idle, but on the other hand is a well charged battery if not being charged at all. Try the voltage at a fast idle - it should increase, but the 14.8 will not necessarily be reached unless the battery is fully charged.
Alternators can be repaired, and this is often cheaper than a new one, or in many cases you can get an exchange one (not sure about yours).
But before doing anything about this, I would check the fan belt tension and any voltage drop between the alternator earth terminal and the battery negative.
John

**feral** · 18th February 2007, 07:01 PM

Thanks John,

I believe the belt would be running a pretensioner so it would always be tight. The belt was changed at 80,000 ks so it should still be ok.

To get a voltage reading I have hooked a multimeter up through the cig. lighter. It is showing 13.1 volts with the air con fan on and nothing much else.
This is even when engine revs are 2500 - 3000 rpm.

At this charge rate I could put any type of battery in and will not destroy it.

Cheers,

**Koukandowie Brangus** · 18th February 2007, 07:55 PM

Take the reading straight off the alternator if you can get to it you may drop half a volt through all the wiring/fuses if its old enough.

**JDNSW** · 18th February 2007, 07:56 PM

Originally Posted by Feral

Thanks John,

I believe the belt would be running a pretensioner so it would always be tight. The belt was changed at 80,000 ks so it should still be ok.

To get a voltage reading I have hooked a multimeter up through the cig. lighter. It is showing 13.1 volts with the air con fan on and nothing much else.
This is even when engine revs are 2500 - 3000 rpm.

At this charge rate I could put any type of battery in and will not destroy it.

Cheers,

If it is only 13.1 volts at 2500, unless your battery is VERY sick, then the alternator is not working properly. Does the voltage change with rpm? If it does, the alternator is working to some extent assuming the belt is not slipping. The problem may not be the alternator itself - could be a bad connection, but the alternator IS the most likely. Checking the voltage at the battery and at the alternator would confirm it is not a bad connection.

John

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