Car chews through Alternator regulators

[Kiwifolk]

Hi guys. Got an interesting issue.
I’m on my 3rd alternator and it’s causing issues.
The battery charges normally at idle and on the gas but over 4500 rpm the voltage randomly drops just low enough to engage the alarm on the dash. 12.3 ish volts.

I’m told is the regulator on the alternator. But it keeps happening.
I don’t really want alternators to become a consumable. Just wondering if anyone might have any ideas what could be causing it to chew through them.

Car is a 2004 VY Calais LS1
New battery
New alternator cables. (Didn’t fix the issue)

 

[Skylarking]

Did you buy the car new and have there been any mods or repairs to the electrical system prior to this issue?

Not sure why you’ve had three alternators replaced when it’s a faulty regulator as you’ve been told. A $60 regulator is an easily removable and replaceable components (also has integrated brushes). Brushes themselves can also be replaced separately on your old regulator for much less but you need a soldering iron to do it.

About the only thing fails in an alternator are bearings (it’s rare but if it spins nicely by hand they are ok), windings overheat and short out (alternator working had to supply more than it is designed for, checked by dismantling and measuring winding resistance), brushes wear out (most common fault and easy to check and to replace) or regulator diodes overheat and fail (pulling too much power from alternator but a new regulator is cheap and easy fix).

Why it’s happened three times, not sure... the failure timeframe would be interesting to know.

Maybe the alternator is not getting airflow for cooling. Maybe you’ve got a killer sound system and a low power alternator. It could be a million things so more info needed to diagnose.

But don’t discount a failing battery as the cause. A battery with a dead can play havoc with the charging process in a modern car where computers, BCM, control the charging process. It’s cheap and easy to get the battery load tested