No output from alternator - thoughts?

I've discovered the battery has suddenly stopped charging on my 1996 Escort 1.8 Zetec. Having stupidly replaced the battery without thinking, I've realised that the problem is with the alternator: When the battery is in reasonable state of charge with the vehicle idling, I'm getting zero volts from the alternator (measured at the battery with a Gunsons Autotune Multimeter). I'm reluctant to pay out for a new or recon' alternator when it might be the regulator/brush unit that is easily changed for =A38. The wiring from the alternator appears OK and I didn't get any warnings from the dashboard light. I would appreciate any thoughts about what step I should take next!

Reply to
Mork (from Ork)
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I think I saw that Halfords are offering a free electrical check - take it there, or somewhere similar, for testing.

Si

Reply to
Mungo "Two Sheds" Toadfoot

Unfortunately I can't drive the car. Because the battery isn't being charged at all, I only get a few miles before the fuel injectors fail and I grind to a halt.

Reply to
Mork (from Ork)

So stick it on a battery charger overnight.

Reply to
Conor

The car will only travel a few miles on a fully charged battery. I had thought to charge the battery before starting it from flat! Remember the alternator's not putting out anything to replenish the battery.

Reply to
Mork (from Ork)

Even with a modern electricly dependant car, with a good battery, you should get at least 20-30 miles with a good fully charged battery in daylight with only the essentials turned on.

Sounds like you have a failed diode which is draining the battery or some other serious electrical problem.

Tim..

Reply to
Tim (remove obvious)

Something is draining it then as it should give a good dozen or more hours.

Reply to
Conor

Unplug the alternator, unbolt the main live wire and tape it up. Try driving it again. Sounds like the diode pack is fried and is a short circuit draining the battery. Don't use the fan or screen heaters and especially not a front heated screen.

Reply to
Peter Hill

I've discovered the battery has suddenly stopped charging on my 1996 Escort 1.8 Zetec. Having stupidly replaced the battery without thinking, I've realised that the problem is with the alternator: When the battery is in reasonable state of charge with the vehicle idling, I'm getting zero volts from the alternator (measured at the battery with a Gunsons Autotune Multimeter).

If you have zero volts at the battery, then the battery is completely flat, and no alternator will generate any power from zero volts.

Reply to
SimonJ

If the engine is IDLING, then there has to be some voltage at the battery, surely ?

If your voltmeter is showing zero, then is it working ? Do you have the test leads connected up correctly ?

Reply to
NT

Check the battery voltage, should be about 12.8 if fully charged, start engine, battery volts should rise to about 14.

A fully charged battery will let you drive around for hours before becoming flat,

escorts have a problem with the alternator main lead, both its connection and routing around the front of the engine bay, but my bet is that you have left off the alternator lead to the battery or even connected it to the wrong terminal of the battery.

mrcheerful

Reply to
mrcheerful

Just to clarify: I'm getting a reading of just over 13v from the battery without the engine running. I'm then switching my trusty Gunsons Testune multimeter to the 'high voltage' range. This specifically tests alternator output. It's reading as near to zero as makes no difference. When the engine revs are raised to 4000rpm, it increases to @ 2v. I'm going to take a gamble and splash out on a Bosch regulator/brush pack. It's only 7 quid. I will report back with the result.

Reply to
Mork (from Ork)

I think that's 0.2 x 100 or even 0.02 x 1000, on high volt ranges it will only show 10v steps. Or you have set it on 20A high current reading and have blown the fuse or melted the solder link in the current shunt, which you will if you put it straight across the battery on a current range or are luckily in the wrong connection on the meter to read current.

You don't change range to read battery voltage - pancake flat or cranking up to running at max alternator output is 9v-14.9v and the

0-20volt DC range will cover it nicely.

I think you better re-read the destructions.

Reply to
Peter Hill

You don't need to alter the range setting, leave it on the range that is showing you 13 volt, leave it connected across the battery, start the engine and rev it enough to put the warning lights out, then read the voltage, it should be about 14v, showing that it is charging, if it drops from your initial voltage then it is not charging.

mrcheerful

Reply to
mrcheerful

If you're reading 0 V at the (new) battery, the battery is shorted (or completely dead)! (Or your multimeter is not set to DC) The solution lies in finding that shortcut... :-(

"Mungo "Two Sheds" Toadfoot" schreef in bericht news: snipped-for-privacy@pipex.net...

Reply to
ICE

Right, in the daylight I've had a chance to look at my meter properly; I'm sorry for causing confusion. My regular multimeter shows 12.7 volts from the battery without the engine running. This makes sense, it's in a reasonable state of charge and it's brand new. With the enging idling and the same range used on this multimeter I'm getting 11.7 volts, with revs increased it doesn't alter.

I replaced the alternator with one from an identical vehicle. Still

11.7v when idling. The only component left is now the wiring as some of you have suggested. I can't see any obvious problems - are there any usual areas to check in detail? I've inspected close to the alternator and it seems fine????
Reply to
Mork (from Ork)

The message from "Mork (from Ork)" contains these words:

Check the alternator warning lamp on the dashboard. Alternators compare their output voltage to what's received through this bulb. If it's blown then you may find there's no output - the drop in voltage is because all the other systems in the car are drawing current.

Reply to
Guy King

Does the 'ignition warning' light work? Switch on without starting and it should remain on after all others have gone out, apart from the oil pressure and handbrake one.

On many models this provides the path for the alternator field voltage, and without field volts you get no output.

A decent maker would put a shunt resistor across the bulb so you still get a charge if it blows, though.

Reply to
Dave Plowman (News)

Thanks for all the advice. I've now sussed out the problem (after raising the vehicle higher allowing me a better view underneath the vehicle). The thicker positive cable to the starter motor solonoid had broken where it was attached to the round terminal. Once connected properly I'm getting 14.2 volts at the battery when idling, reducing to 13.7 under load with the heated screen, blower and lights on. For reference the ignition warning light was not on even though it is working.

Reply to
Mork (from Ork)

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