Thread: Help! Alternator Failing?

Im no expert but if its running at 13.8 volts at idle it sounds quite normal.
I have a similar alternator on my stage 1 and it only puts out 13.8 at idle I took it to an auto elect and replaced the regulator and it still only charges at 13.8
All this and the alternator is only new.
How many spotlights do you have?
If you rev the engine up with the lights on does the voltage increase?
What size battery does it have in it if its a normal z70 then with a series petrol with nothing but the fuel pump and ignition will usually do more than 500 km.
Start it with the crank handle and preserve the battery if you turn it off.

This may not be politically correct but considering where you are on the way back look for an ex indigenous XD Falcon I think the Alternator will have the same guts.

Originally Posted by Davo

We are visiting friends on a station on the Gibb River Road in the Kimberley with our SIIA. Last night I went for a short drive and while the voltmeter showed a normal charge with the engine running but no lights on, as soon as I switched on the headlights and then the spotties the volts dropped right down to below 12v. I checked the alternator outlet with a voltmeter and indeed it was putting out about 13.8v at idle, no load, and 12v or less at idle and lights on.

The alternator is a year-old Bosch BXH1236, the type used for Holden red motors, so it's nothing exotic. (Though it's made in China, I see, and not Oz, like they used to be.)

We've got 528kms to get home tomorrow, so what do you mob think? If the alternator is fine with only the ignition and electric fuel pump loading it should it last to get us home? Am I right in assuming it's the alternator failing? Also, with everything off I noticed a small spark when removing and replacing the earth lead. Is that a clue?

regulator pack is failing

DAVO , if the voltage does not increase with headlights etc. on and engine revved up I would say a diode in rectifier or stator failed. An alternator has 3 phases and if you lose a phase then you lose output hence 13.8 v no load when you load it up with headlights etc. alternator cannot keep up due to failed phase\phases. Should be ok to drive during day.

Everyone, thanks very much for your replies. It looks like we'll head to a nearby station or Kununurra tomorrow, (Sunday), and try and find something. If need be, we'll just wait in Kununurra if a new alternator has to be ordered.

I wouldn't mind so much if we were just on holiday but we're only trying to get back home!

I think I might take my old made-in-Oz alt to an auto sparky and get them to rebuild it so I don't have to rely on more Chinese stuff!

if your only running during the day you only need 5-8 amps of power to keep it running

a 60w solar panel on the roof and charging the battery overnight will get a series rover anywhere for daylight running only.

Originally Posted by Blknight.aus

a 60w solar panel on the roof and charging the battery overnight will get a series rover anywhere for daylight running only.

Hey Dave do you want to think about that suggestion more closely?

Perhaps you meant a solar panel during the day whilst driving (strategically mounted on the roof rack perhaps) and a battery charger overnight? (Or perhaps in 'beautiful one day, perfect the next' QLD you have a brighter moon than we have down south!)

Now this just emphasises why it's so important, when communicating in English, to get the wording right.

I agree with the diagnosis - most likely a dead diode or two in the rectifier so one phase is not contributing. Remember that although an alternator is much better at supplying charge current at low revs than a generator (dynamo) it still won't charge very well at idle. 13.8V is quite normal at idle but the output should go up a bit to around 14.0 to 14.2V by 1000RPM or so with light load (no head lights or spotties).

It sounds as though the alternator is able to supply enough current to keep up with the load from the coil' fuel pump and instruments so you could make a run for home but if something goes wrong you're a long way from help. In your shoes I'd be heading for Kununurra (bit I'm not a risk-taker by nature).

Good luck with the trip.

Originally Posted by GrahamH

Perhaps you meant a solar panel during the day whilst driving (strategically mounted on the roof rack perhaps) and a battery charger overnight? (Or perhaps in 'beautiful one day, perfect the next' QLD you have a brighter moon than we have down south!)

yeah that.