Wouldn't It Rot Yer Boots

[echnidna]

Wouldn't It Rot Yer Boots - an off topic car problem

My old hilux has started to get a flat battery - sometimes.
I stuck an ammeter in the battery lead the other day and there was a 2.2 amp leakage current with everything turned off. I noticed a click noise each time i connected/disconnected the battery and hunted it down to the external alternator voltage regulator. Left the battery disconnected for a couple of days.

Today I started the engine up and when i turned it off there's no clicking or leakage current when I connected/disconnected the battery after running the engine -- bugger.

I was going to send it off to the autoelec's which ****es me off cos I was an autoelec before Noah started wearing nappies and cars have changed lots since then. If I had a wiring diagram I'd probably find the problem.
At the moment I reckon it might be any of
1. wiring fault
2. regulator fault
3. alternator fault
4. Bodgy ignition switch
5. Defective engine/start etc relay.
or some other confounded thing.

Trouble is intermittent electrical faults are a major pita to diagnose then repair and can cost lotsa loot for simple repairs. At the moment I'm disconnecting the battery when I stop the engine.

So has anyone with a hilux or any autoelec got a suggestion

 

[Willowbilly3]

It's generally not that hard to trace down a drain on the system.

 

[earthman]

Just see if there is current at the alternator with the switch off. If it is then it will likely be the voltage regulator. Sounds almost like i know what i'm talking about.

 

[echnidna]

The click is the regulator, If I unplug it no noise but that means it's

1. wiring fault
2. regulator fault
3. alternator fault - highly unlikely but i suppose it might be possible
4. Bodgy ignition switch
5. Defective engine/start etc relay.
or some other confounded thing.

I'm inclined to think its item 4 or 5 but the problem is intermittent.

 

[echnidna]

I got a reply from an autoelec on another forum.
I'm posting his reply here so it can help anyone else with a similar problem

"The clicking was the warning light relay part of the regulator, which is switched by the alternator star point. The 2.2 amps draw is the alternator field circuit winding current draw.
The problem is that one or more of the positive diodes are faulty and allowing leakage to the star point ( 7 volts normally) which switches the regulator. If you leave it happening it will also burn out the warning light relay coil in the regulator and cost you both an alternator and regulator, if it hasn't done that already.
Forget the isolator, relays etc and fix it now.
Cheers.'

 

[donsrods]

Yes, years ago my then wife had a Buick that would start fine every morning during the week but after sitting unused for the weekend the battery would be dead. Long story short, there was a bad diode in the alternator that was draining just enough juice that if she drove it every day it would recharge the battery. But laying dormant for two days allowed the battery to go completely dead.

Don