Author Topic: Tough Alternators.  (Read 637 times)


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Tough Alternators.
« on: April 24, 2019, 02:36:26 PM »

I have played with and admired the robustness of twin/ concealed fan modern alternators for a while now and the abuse I have given them without having one fail.

Had a ( too ) graphic demonstration of just what these things will do last week.
For a couple of weeks the lights on the dash of my ute have been flickering a bit, going out and then resetting like the ignition was just turned on while the car happily drove up the road.
Last week up at my fathers place I put the old girl up on the house and did a bit of work to it.

I thought I had a bad connection somewhere but eliminated that and looked at the alternator. I pulled out the regulator and saw the internal contacts were really corroded and dodgy looking so cleaned them up and re installed which made the problem seem to go away.
Threw a new serpentine belt on the thing, tightened the steering rack a touch, changed the PS fluid, pulled all the wheels off and balanced them which they had changed a surprising amount in a short time (wobbles wasn't my imagination after all ) and called it all good.  So I thought.

About 30  min into the 4 hr Journey home, the dash lights started flickering again as did the headlights brighten and the thing mucked around for a bit before I got a constant battery light.

Once I got off the freeway though I could smell something definitely Funky but wasn't concerned because I knew if the alternator popped now I could make it home without question on the battery alone.
As I got up the driveway I could see wisps of steam coming out the bonnet and thought Oh ohh, I think I had this all backwards. Should have known but I was tired from the driving and mentally exhausted from dealing with morons every day for 2 weeks looking after the business for Dad.
He can't do this anymore, I'm going to wind it up for him at financial years end so he doesn't have the stress any longer. No one can take that especially an 80 Yo.

If i had been at home I would have worked out the problem but I just wanted to get home and see my wife and daughter whom I had been missing... for inexplicable reasons.

Sure enough, I lift the bonnet and the battery is boiling like a tea kettle. Leave the thing running, grab a multimeter and I have 19 + Volts. I was then surprised the headlights and stereo hadn't blown hours ago. 
The battery was wharped and I was concerned and amazed it hadn't exploded. I turned the engine off and the alternator was intensely hot as well.
Poured water over the battery to cool it and took off the caps to find no water at all.  Refilled it and the water I put in started boiling.

Clearly the regulator had gone and the alt was pushing the full 110A and had been for at least 3.5 hours.  Impressive if not desirable.
Had I the smarts to realise what was happening I could have disconnected either the field wire or the output and driven the thing at least an hour on battery then hooked it up again to charge and repeated.

Next day I come out and battery is toast and bulged like a balloon.  Wash around the thing real good top and bottom to get rid of the acid deposits.
I get the old battery I replaced a few weeks ago and it has enough kick to just fire the thing up.  Put a multi on the battery and the Voltage is shooting north indicating the alt is still pumping out full charge.  Give the batt a top up then switch the car off.

I have played with these internal fan Alts a lot before and never broken one for trying.  I have run them overloaded for period of time and got them hot but never  for as long or as hot as this one had been.  The ones I normally play with a mitsubishis but this one was a Bosch of the same twin, internal fan design. I looked at replacing the Bosch with one of about the 9 Mitsi's I have but way too hard and fraught with danger.

I really admire these things. Far as the windings go they seem virtually indestructible. I put that down to the cooling ability of the twin fans they have inside that cool the windings and the electronics.... for all that did this time.  Probably still kept the alt from burning off the enamel from the wire if nothing else.

I have also run these alts with no battery direct to a load for long periods which is supposed to be a no no and never had a problem and also fed them full battery voltage for hours and they have not flinched at that either.
Running one in an engine bay flat out for hours and boiling a substantial battery dry and surviving is something else.

Us old engine lovers are always looking for the bullet proof and I have had many people express reservations about using car alts before but I think this really shows how tough they are built.  I have no idea how old this thing is, could be the original as fitted as every thing points to that which would make it 17 years old with over 171K Km on the clock.  For those in the US, 171K Km is...... 171K Km!  :0)

New alt from fleabay is going to be $130 delivered which I think is great value.  Local wreckers quoted $95 for a used and wanted the old unit as exchange.  I'll keep that as it's working well and see how it goes with the reg replaced. I have another alt up the back off the same model but the thing seemed to be dragging in the bearings so I'm not enthused to fit that especially as I'll be clocking up some miles up and down the highway in the next couple of months going up to look after Dad.

Battery will probably add insult to injury.  That will set me back $150 at least.
Hopefully the alt will be the last one the ute ever has and will last me out as well but there will be a few more battery's to come yet.

I'd never have any hesitation in relying on these style alts for home backup power. Run in the far more cooler and kinder conditions of a stationary application, with a set of bearings and brushes/ regulator pack they would last a very long time I believe and could be relied on to put out very solid power. I have 2 Mounted on my 'roid which would easy supply a 2 Kw inverter and charge battery's at the same time.

If one assumes an average speed of 40 Kmh which I think is high for a city car, this would give the life of this alt as being about 4275 hours.
With the exception of we willy weirdos 10K hr engines, I don't think there would be many that could do that sort of hours untouched as this alt  seems to have been.

No doubt even at 12V, this thing has generated a LOT of Kwh and isn't done yet!