Alternator fault

[The Bearwood Boster]

Hi folks, I have a problem with one of my alt' which hopefully one of the experts on the forum can help me with.

 

I have twin 70A alt's on a Izuzu engine with an adverc controller, onto a start battery and 4 x 125Ah battery domestic bank.

 

The aux warning light on my instrument panel is glowing.

 

When I put a meter from the B+ to ground and then the D+ to ground on my port alt' both show the same volt (circa 15v)

 

when I do the same for the s/b alt' the B+ shows the same volts as the port alt' (circa 15V) but the D+ which feeds one side of the warning lamp is showing 19V which is I

 

assume why the warning lamp is glowing. I guess this means I have an internal fault with this alt' and it will need to be removed for testing/fixing. Is my guess correct?

 

Will I damage anything by running the engine and still charging the battery banks until I remove the s/b alt'?

 

Thanks to anyone who has the time to reply.

 

Regards

[Nickhlx]

Hi folks, I have a problem with one of my alt' which hopefully one of the experts on the forum can help me with.

 

I have twin 70A alt's on a Izuzu engine with an adverc controller, onto a start battery and 4 x 125Ah battery domestic bank.

 

The aux warning light on my instrument panel is glowing.

 

When I put a meter from the B+ to ground and then the D+ to ground on my port alt' both show the same volt (circa 15v)

 

when I do the same for the s/b alt' the B+ shows the same volts as the port alt' (circa 15V) but the D+ which feeds one side of the warning lamp is showing 19V which is I

 

assume why the warning lamp is glowing. I guess this means I have an internal fault with this alt' and it will need to be removed for testing/fixing. Is my guess correct?

 

Will I damage anything by running the engine and still charging the battery banks until I remove the s/b alt'?

 

Thanks to anyone who has the time to reply.

 

Regards

 

Is this a new installation or one that has been working for a while ? ( possible installation error )

 

Also have any electrical alterations ( additions or removals) happened just before this issue started or any other electrical events ? e.g. any welding done to boat or inverter replaced / washing machine installed / microwave installed etc ?

 

Nick

Edited February 16, 2011 by Nickhlx

[Robin2]

This sounds very like my problem One Alternator Won't Charge

 

Are your two alternators connected together?

 

Have you two low-charge warning lights? Is so which one is glowing?

[dccruiser]

My initial thought would be that you have a faulty regulator on the alternator that is showing a 19 volt output.

 

But personally without a lot more information it is hard to properly diagnose, although others may be able to inform you better.

The questions i would need to ask are,

 

Are both alternators wired for use with an adverc controller?

 

Are all connections clean and well made?

 

Does the engine speed have any bearing on the 19volt output, or is it static irrespective of the engine speed?

 

Are they wired independantly, one for start and one for leisure, or wired to give a combined output? if the latter is the case, then i would disconnect the suspect alternator and just run on the good one until you can remove it to have it checked or repaired.

 

Any further information you can provide as i said would certainly help!

 

Rick

Edited February 16, 2011 by dccruiser

[Sir Nibble]

This is not a guess.

You have a failed main output diode. Ask an auto electrician for a quote on replacement and compare with replacement alternator price.

If the light is on with engine stopped and ignition off, don't use it, that is a short in a +ve diode.

Get it fixed asap and check that the ventilation slots in the alternator are not obstructed by crap or nearby hardware and that engine compartment is well ventilated.

[Arnot]

Hi folks, I have a problem with one of my alt' which hopefully one of the experts on the forum can help me with.

 

I have twin 70A alt's on a Izuzu engine with an adverc controller, onto a start battery and 4 x 125Ah battery domestic bank.

 

The aux warning light on my instrument panel is glowing.

 

When I put a meter from the B+ to ground and then the D+ to ground on my port alt' both show the same volt (circa 15v)

 

when I do the same for the s/b alt' the B+ shows the same volts as the port alt' (circa 15V) but the D+ which feeds one side of the warning lamp is showing 19V which is I

 

assume why the warning lamp is glowing. I guess this means I have an internal fault with this alt' and it will need to be removed for testing/fixing. Is my guess correct?

 

Will I damage anything by running the engine and still charging the battery banks until I remove the s/b alt'?

 

Thanks to anyone who has the time to reply.

 

Regards

It sounds like a rectifier problem to me.

 

If this is the case then you will need to get the alternator off for repair or replacement at some stage but by the sound if it there is still some output.

 

Continuing to run it will probably not make the problem worse but the unit may fail completely shortly anyway.

 

Although it may just be a random failure, it might be worth looking into why it failed, rectifier problems are unusual nowdays. Things to look for are poor cooling of the engine hole and/or the alternator output being routed through a master switch that is starting to fail.

 

Regards

 

Arnot

 

PS beaten by Snibble - again! Hi Snib.

Edited February 16, 2011 by Arnot

[Sir Nibble]

It sounds like a rectifier problem to me.

 

If this is the case then you will need to get the alternator off for repair or replacement at some stage but by the sound if it there is still some output.

 

Continuing to run it will probably not make the problem worse but the unit may fail completely shortly anyway.

 

Although it may just be a random failure, it might be worth looking into why it failed, rectifier problems are unusual nowdays. Things to look for are poor cooling of the engine hole and/or the alternator output being routed through a master switch that is starting to fail.

 

Regards

 

Arnot

 

PS beaten by Snibble - again! Hi Snib.

I saw you were posting as I poted my own answer. I knew you would concur, it's a pretty cut and dried case. I would not use it with a shorted diode 'cos of stator overheating.

[Arnot]

I saw you were posting as I poted my own answer. I knew you would concur, it's a pretty cut and dried case. I would not use it with a shorted diode 'cos of stator overheating.

Quite possibly true, my logic was that it was a main pos diode o/c and when the others took the load they would probably follow shortly anyway but it would buy a bit of time.

 

Usually the 70A option in the Isuzu is a good ole A127 and they usually have rectifiers built of sealing wax and string. The non gen items seem to be better, what say you?

 

Either way it sounds fubared...

[Sir Nibble]

Quite possibly true, my logic was that it was a main pos diode o/c and when the others took the load they would probably follow shortly anyway but it would buy a bit of time.

 

Usually the 70A option in the Isuzu is a good ole A127 and they usually have rectifiers built of sealing wax and string. The non gen items seem to be better, what say you?

 

Either way it sounds fubared...

Yea the non gen ones with copper heatsinks do seem more robust and I thought it was probably an A127 since this seems one of its preferred means of suicide. Don't help when f**kwits at rover fit them with the cooling air drawn straight off the exhaust manifold. I have seen at least as many fail s/c as o/c so it seemed sensible to suggest a little test. As an aside, it has been so nice this winter to show up at the college and go into the toasty warm instead of grovelling under some car in the freezing cold education is SO good for me!