[Moph]

Lights are steady with engine off, but at any revs they pulse at about 80-90Hz. Really frustrating to drive with, especially the dash lights.

Have good earths body - chassis - engine - battery (all 80A+ rated). Tried bit of wire from alt to battery and alt to headlight light earth direct just in case, but no luck.

Ford alternator ... only about 5,000km old ... not seen any mud. Suspecting dud regulator?? Can they be changed over, or are they internal?

[fordem]

I'd suspect the rectifier diodes in the alternator - the alternator as the name suggests generates 3phase AC power which is then rectified with a six diode bridge rectifier.

The regulator is fairly easy to check with a good voltmeter - hook it up across the battery terminals - engine off, it should give you something in between 12~13V, depending on state of charge - slightly less is also possible on an older battery - start the engine and you should see a drop in voltage whilst cranking and once the engine starts the voltage should increase by one or two volts - coming to rest at somewhere between 14~15V.

Now - 80~90Hz - can you actually see that? The human eye as a rule does not - mains a/c power is either 50/60Hz depending on country and not visible to most people.

[Moph]

Duh ... sorry, not 80-90Hz ... 80-90 cycles per minute

Will hook up the multimeter tomorrow ... to dark and cold tonight. Cheers.

[Moph]

Grrrr. Got over the cold and dark thing - voltage wandering between 14.2-14.7V with alternator cranking; multimeter doesn't settle on voltage.

Swapped to spare alt and good as new.

So a dead alt after only 5000km ... and it was brand new! Any ideas?

[89_tintop]

Where did you pic up the "sense" wire from??

[Moph]

Sense wire is standard end-of-loom one ... reckon it's got too much voltage drop? Was sitting at 14.7v charge with new alt; battery was down a bit as the Zook hasn't been out in a while.

[royce]

compare the voltage at the sense wire and battery, make sure everything electrical is off, especially the stereo

do you have dual betteries? what controller?

[Moph]

Sense wire is the red/white one yeah? It's sitting at 14.35V at idle while battery is 14.8V, so 0.45V differential. That's with absolutely everything switched off bar the dash clock and standby power to the amp (too difficult to isolate).

Charged battery overnight and am now seeing 15V at battery with some revs.

Single battery only Royce - 470CCA RC85.

[royce]

red white is the warning light, black white is sense

[Moph]

Ah crap - thanks.

The black sense wire is at 14.6V while the battery is at 15.0V. Not sure why it bumped up battery voltage from 14.8V last time, but triple checked it at 15.0V this time. So 0.4V differential.

Not sure if loaded voltages are any help. The following are with stereo, amp, high beams (2x130W), HIDs (2x55W) and aircon on/off as the compressor cut in/out.

Sense --> Battery
13.4V --> 15.1V AC compressor on
14.2V --> 15.9V AC compressor off (jumps up instantaneously)

Does that look right??

It often gets worked pretty hard with night driving - Engel fridge (3A), stereo (10A at normal levels say), headlights (20A), 4xHIDs (15A) ... so around 50A draw wouldn't be unusual, plus charging the battery from time stopped with fridge and stereo on.

[skyman]

I would be hooking the sens wire directly to the battery so you do not end up with an over-volted battery.

However Royce is troubleshooting this one, so defer to his judgment especially if it differs from mine

[royce]

yeah run them tests with the sense hooked up to the battery, note dont leave it like that cause it might cook something

Though it doesnt make sense to me and I dont think these alternators are as robust as everyeone makes out (mine used to make the headlights blow when you switched em on, great idea)

also check the sense voltage with ignition on and engine off, see if you get a similar drop