Last year the alternator on my Toyota cooked the stator windings. I didn¹t
look any further and replaced it with a rebuilt alternator & regulator from
the local parts supplier.

Now (7 or 8 months later) the replacement has failed in the same mode. I¹m
suspicious. Also confused:

If a diode opens there wouldn¹t be an increased load on the stator windings.
If a diode shorts, there also wouldn¹t be any increase, just a decrease in DC
output voltage.

If the alternator output is shorted, since it¹s connected directly to the
battery (+) terminal, this would result in smoke and fire, at least a burnt
fusible link. None of this has occurred. (Well, the windings are discolored
and the smell is what clued me in to these problems.) When I put in a
replacement alternator I¹m quite confident everything will look just fine.
Until next time. *

What could cause these symptoms? Twice?

Thanks!

"Sparky" wrote in message
...
Last year the alternator on my Toyota cooked the stator windings. I didn¹t
look any further and replaced it with a rebuilt alternator & regulator
from
the local parts supplier.

Now (7 or 8 months later) the replacement has failed in the same mode. I¹m
suspicious. Also confused:

If a diode opens there wouldn¹t be an increased load on the stator
windings.
If a diode shorts, there also wouldn¹t be any increase, just a decrease in
DC
output voltage.

If the alternator output is shorted, since it¹s connected directly to the
battery (+) terminal, this would result in smoke and fire, at least a
burnt
fusible link. None of this has occurred. (Well, the windings are
discolored
and the smell is what clued me in to these problems.) When I put in a
replacement alternator I¹m quite confident everything will look just fine.
Until next time.

What could cause these symptoms? Twice?

Thanks!

Did you change the battery any time after the alternator was changed or is
it the same one still?

On 16.2.15 16:01, Sparky wrote:
Last year the alternator on my Toyota cooked the stator windings. I didn¹t
look any further and replaced it with a rebuilt alternator & regulator from
the local parts supplier.

Now (7 or 8 months later) the replacement has failed in the same mode. I¹m
suspicious. Also confused:

If a diode opens there wouldn¹t be an increased load on the stator windings.
If a diode shorts, there also wouldn¹t be any increase, just a decrease in DC
output voltage.

If the alternator output is shorted, since it¹s connected directly to the
battery (+) terminal, this would result in smoke and fire, at least a burnt
fusible link. None of this has occurred. (Well, the windings are discolored
and the smell is what clued me in to these problems.) When I put in a
replacement alternator I¹m quite confident everything will look just fine.
Until next time.

What could cause these symptoms? Twice?

Thanks!


Bad battery which does not let the voltage to rise, or too much load,
but not enough to blow the fuse. A winding can be fried with a slight
overload and limited cooling.

Do you happen to have quadruple 300 W audio channels on board?

--

-TV

Sparky wrote:

If a diode shorts, there also wouldn¹t be any increase, just a
decrease in DC output voltage.
No, ONE a shorted diode would cause huge currents in the winding
connected to that phase. Two shorted diodes on the same
phase would cause huge DC currents and blow the fusible link.

Jon

On Mon, 16 Feb 2015 06:01:09 -0800, Sparky wrote:

Last year the alternator on my Toyota cooked the stator windings. I didn¹t
look any further and replaced it with a rebuilt alternator & regulator from
the local parts supplier.

Now (7 or 8 months later) the replacement has failed in the same mode. I¹m
suspicious. Also confused:

If a diode opens there wouldn¹t be an increased load on the stator windings.
If a diode shorts, there also wouldn¹t be any increase, just a decrease in DC
output voltage.

If the alternator output is shorted, since it¹s connected directly to the
battery (+) terminal, this would result in smoke and fire, at least a burnt
fusible link. None of this has occurred. (Well, the windings are discolored
and the smell is what clued me in to these problems.) When I put in a
replacement alternator I¹m quite confident everything will look just fine.
Until next time. *

What could cause these symptoms? Twice?

Thanks!

Does the alternator use Avalanche Diodes? A bad battery wiring
connection will cause a diode to short. I'd check the terminals and
crimps.

BTW I had this problem with the double GM battery lugs, they used a
lead spacer that shrunk when it thermal cycled.

\Cheers

Sparky wrote:
Last year the alternator on my Toyota cooked the stator windings. I
didn¹t look any further and replaced it with a rebuilt alternator &
regulator from the local parts supplier.

Now (7 or 8 months later) the replacement has failed in the same
mode. I¹m suspicious. Also confused:

If you asked in rec.autos.tech you'd get answers with less knowledge of
theory but with more knowledge of common failure modes.

--

Alternators are **** today. In the old days you could replace one, take the cablesoff a good but completely dead battery and start it with a another and then connect the battery to charge. Sometimes it would slow down the engine because of the load. A dead but good battery is almost a short circuit. Those old alternators could handle it but not the new ones. It even should says in the instructions to make sure the battery is charged before starting that car after replacing the (****) alternator. (let's not even go into a few Chevy engines where you have to damnear remove the engine to change it, and they are a high failure part)

You would not get the same thing likely with two alternators in a row unless it is a common failure. The problem MIGHT be an overload but it would be one that is only there when it is running, otherwise any short that heavy would kill the battery and it would not start the next morning.

Problem is they don't put a proper ammeter in cars anymore. I don't even want to go into telling you how to hook one up. The starter motor has to be isolated and on some cars this is damnear impossible. You don't want to read the starter amps on the ammeter, it is too high and you would need a proper scale and that would be too high to see if this is the problem.

The only real way to do it these days is at the alternator itself, that will not indicate discharge like in the old days but it can tell you how much current is being pulled. The fattest red wire on it, take it off and put the ammeter there. The alternator has a rating, if the constant drain without the headlights and AC on is near that rating there is an overload. Not a dea short so an ohmmmeter will not tell you where it is. It could be almost anywhere, one of the coils or cokl drivers, fuel pump, or some modification like those road lights or blue diamond headlights with the ballasts or who knows.

It could also be that the engine is running too hot, concievably. That is not the most likely though. It is also possible that the alternator is simply underbuilt for the car. that is actually pretty likely, it would not be the first time I saw it happen.

Did you change the battery any time after the alternator was changed or is
it the same one still?

Replaced with new from NAPA auto parts, not the cheapest, but a quality one.

Do you happen to have quadruple 300 W audio channels on board?

No, mostly stock old Toyota. Only additional load is Xenon lamps. These pull
10A total which isn't much for lights...

Maybe I'll upgrade the alternator to a later-model Toyota 70A or such.

If you asked in rec.autos.tech you'd get answers with less knowledge of
theory but with more knowledge of common failure modes.

THANK YOU! Hadn't crossed my mind (being the eletrickery kind of guy that I
am...)

Best day to you!

No, ONE a shorted diode would cause huge currents in the winding
connected to that phase. Two shorted diodes on the same
phase would cause huge DC currents and blow the fusible link.

Jon

Ah. Then might be one shorted diode... Should probably upgrade alternator to
a higher-amp one that can handle the car's load more easily.

On 2/16/2015 10:16 PM, Sparky wrote:
Do you happen to have quadruple 300 W audio channels on board?

No, mostly stock old Toyota. Only additional load is Xenon lamps. These pull
10A total which isn't much for lights...

Maybe I'll upgrade the alternator to a later-model Toyota 70A or such.

What is your current unit rated for 60A?

I replaced the 70A alternator in my truck when a diode opened up. It
was still working, but not enough juice to charge the battery when the
lights were on and I run the headlights all the time, lol. Nothing ever
got fried though.

What is your alternator model number? What year? Mine is a 97 T100 and
I found they changed the alternator in mid model year (around April,
IIRC). Causes a lot of confusion on what is the right model. I tried
finding a replacement diode bridge. *That* was the major change and was
incompatible between the two versions. When looking for parts be sure
to use the VIN to get the right one.

I ended up getting a used alternator and it is running ok now...
although it is in the shop for a clutch. They've ordered two so far.
The first pressure plate "collapsed" whatever that means and the springs
on the second weren't right. They are giving NAPA some hell over this
and are getting an upgraded one to put in my truck. Hope to have it soon.

--

Rick

I'd have to agree with connections. I did, however hear of an internally corroded battery cable. I once had a corroded bulkhead connector do it.

In one case the paint shop didn;t tighten the battery cable. Could I prove it? NO!

Between the bulkhead connector and the alternator where the rotot solder joint just broke, I don't know what was more difficult. The corrosion was harder to find. The broken rotor connection gave no indication, whatsoever. The car just stopped.

The battery was replaced at the same time as was the alternator: 5 months ago
(corrected from my original post).*

Measurement of battery cables: from battery cable (+) terminal to alternator
(+) terminal: 1.5 ohms. From battery cable (-) terminal to chassis: 1.5
ohms.*

Charging numbers with new alternator & 5 months old battery:
With partially (50%?) depleted battery, when the car was started and engine
revved, the new alternator output 34 amps, headlights off. With lights on
high, output was 44 amps. Charge voltage was 14.04 volts. These numbers are
within those specified in the Toyota factory manual (charge current: ³30A or
more²; charge voltage: ³13.9-15.1².*

Thanks.

On 18.2.15 09:27, Sparky wrote:
The battery was replaced at the same time as was the alternator: 5 months ago
(corrected from my original post).

Measurement of battery cables: from battery cable (+) terminal to alternator
(+) terminal: 1.5 ohms. From battery cable (-) terminal to chassis: 1.5
ohms.

Charging numbers with new alternator & 5 months old battery:
With partially (50%?) depleted battery, when the car was started and engine
revved, the new alternator output 34 amps, headlights off. With lights on
high, output was 44 amps. Charge voltage was 14.04 volts. These numbers are
within those specified in the Toyota factory manual (charge current: ³30A or
more²; charge voltage: ³13.9-15.1².

Thanks.


Your measurements cannot be good, or the thing does not charge
the battery. If there were only 10 A, you'd lose 30 V in the cables.

For starting, you will need hunders of amperes, but the battery
voltage cannot put even 10 A to the grounding cable.

--

-TV

Sparky wrote:
The battery was replaced at the same time as was the alternator: 5
months ago (corrected from my original post).

Measurement of battery cables: from battery cable (+) terminal to
alternator (+) terminal: 1.5 ohms. From battery cable (-) terminal to
chassis: 1.5 ohms.

That resistance is too high, maybe because you measured from a bad contact
point.

On Mon, 16 Feb 2015 19:31:57 -0800, Sparky wrote:

No, ONE a shorted diode would cause huge currents in the winding
connected to that phase. Two shorted diodes on the same
phase would cause huge DC currents and blow the fusible link.

Jon

Ah. Then might be one shorted diode... Should probably upgrade alternator to
a higher-amp one that can handle the car's load more easily.

Do you have one or both old alternators? How about checking out the
diodes in them?

I try to fix everything that breaks myself. I'll let something stay
broken for years while I try to figure out how to fix it, rather than
pay someone. Of course I can't let the car stay broken for more than a
day.

When my brother gave me his car, he had a problem with a battery that
repeatedly went dead, for more than two years, ever since he bought the
car new. It came with a 2-year warranty and the dealer had replaced the
alternator, the regulator, and the battery, each of them twice, and
still the problem. Then the dealer said the warranty had expired and
wouldn't do anymore.

Annoyed, he gave me the car. It had a another bad battery by this time
and I took it to Sears. They said do you want our free 235,000 point
multi-check? I said, No, just a battery. He said, It's free. I said
okay. And in less than 5 minutes he found the problem that the dealer
couldn't find in 2 years. In my case it was a bad connection at the
starter motor with the + battery cable. He took it apart and cleaned
it**. I don't know what the problem is with yours but sometimes it
pays to pay someone. Also many people tend to spend all their time on
the big parts and not enough on the wires between them.


**I also bought a new battery, but it's cleaning it that made it work
fine, until months later, I left the headlights on all night. Jumped the
battery and ran the car an hour but it still wouldn't start the next
day. I had to crawl underneath, take the cable off, clean everything
and put it back. Until the next time I left the lights on.
Eventually I learned, even in good clothes, to just stick my arm
underneath, grab the battery cable and pull it back and forth, rotating
on the stater motor stud, once or twice, and then the car would run fine
until the next time I left the lights on. I've run down the battery by
leaving the lights on on other cars without having any endruing
problem. I don't know what made this car different, but my point is that
Sears found the problem in less than 5 minutes.

He gave me the car when he went to Viet Nam, in 1967, but the story
still applies.

On Wed, 18 Feb 2015 06:58:13 -0500, micky
wrote:

**I also bought a new battery, but it's cleaning it that made it work
fine, until months later, I left the headlights on all night. Jumped the
battery and ran the car an hour but it still wouldn't start the next
day. I had to crawl underneath, take the cable off, clean everything
and put it back. Until the next time I left the lights on.
Eventually I learned, even in good clothes, to just stick my arm
underneath, grab the battery cable and pull it back and forth, rotating
on the starter motor stud, once or twice, and then the car would run fine
until the next time I left the lights on.

This sounds like the nut was loose that held the cable on. I'm never
quite sure how much to tighten nuts but it was pretty tight. It's
mostly that I had a lot of leverage pulling on the cable 3 and 4 inches
from the pivot point.

And the mechnanics who changed the starter twice should have known how
tight to make the nut (At least the dealer said he changed everything
twice. When I moved to the city my brother was in, 3 years later, a
year after he left the army, the dealer was out of business!)

I thought about changing the battery cable for one that might not be so
touchy, but instead I found a buzzer that buzzed if I left the
headlights on. That prevented both the ongoing problem and the first
day's dead battery. Problem solved.

Do you all think a different battery cable might have worked better?

"Tom Del Rosso" wrote in message
...

Sparky wrote:
The battery was replaced at the same time as was the alternator: 5
months ago (corrected from my original post).

Measurement of battery cables: from battery cable (+) terminal to
alternator (+) terminal: 1.5 ohms. From battery cable (-) terminal to
chassis: 1.5 ohms.

That resistance is too high, maybe because you measured from a bad contact
point.

Typical meter leads have a resistance of 1.5 ohms. It's possible he did not
short the leads and zero out the meter first. If not, then the battery cable
resistance actually drops to zero.

On Wed, 18 Feb 2015 09:46:23 -0500, Rich. wrote:

Typical meter leads have a resistance of 1.5 ohms. ...

I hope not a meter that claims to measure currents of (say) 10 amps!

Mike.

I hope not a meter that claims to measure currents of (say) 10 amps!

Mike.

He was speaking of when I measured the resistance of the cables and
terminals. Not current.

A second test of the cables, this time using an ESR meter capable of
measuring hundredths of ohms and able to null test lead resistance.

(-) battery cable, from battery terminal to chassis: 0.02 ohms;
(+) battery cable, from battery terminal to starter solenoid: 0.05 ohms;
Alternator cable, from alternator to starter solenoid: 0.33 ohms.

These measurements were done with (-) cable disconnected from battery post
(no potential across cables) and test leads nulled.

So 35 amps charging current over 0.33 ohms pretty much drops the full 12
volts.

I'll look into wiring and terminal issues.

Thanks to all who helped.

On 02/18/2015 6:09 PM, Sparky wrote:
A second test of the cables, this time using an ESR meter capable of
measuring hundredths of ohms and able to null test lead resistance.

(-) battery cable, from battery terminal to chassis: 0.02 ohms;
(+) battery cable, from battery terminal to starter solenoid: 0.05 ohms;
Alternator cable, from alternator to starter solenoid: 0.33 ohms.

These measurements were done with (-) cable disconnected from battery post
(no potential across cables) and test leads nulled.

So 35 amps charging current over 0.33 ohms pretty much drops the full 12
volts.

I'll look into wiring and terminal issues.

Thanks to all who helped.


Um, the 12V drop would only be if the alternator cable wire was shorted
to ground/chassis. You would then be dissipating something like 400
watts through that wire! Ouch!!

It is the total resistance of the circuit that counts, not just one part...

John :-#)#
--
(Please post followups or tech inquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

On Wed, 18 Feb 2015 17:27:55 -0800, Sparky wrote:

I hope not a meter that claims to measure currents of (say) 10 amps!

Mike.

He was speaking of when I measured the resistance of the cables and
terminals. Not current.

I was assuming it was a multimeter. Low[er] resistance leads on any multi-
purpose meter are useful!

Mike.

One of the things I do is to basically turn on the high power stuff and measure the (voltage drop) between the output terminal of the alternator and the battery. I keep that number around although now I have the ability to do non-contact measurements of current.

That cable acts as a ammeter shunt, just not calibrated. It can be used as a benchmark, though.

You could also have an engine ground bond broken.

So thinks like looking at odd places like the wire to to stud when cranking.. It might look like your measuring the same place, but in reality, your looking at the quality of the crimp.

In a lot of cases the rotor gets powered from the ignition switch so that there is no leakage when off. So,, problems can be there too.

So look at voltages across terminals under load and look for corroded bulkhead connectors.

A very simple high resistance crimp is a possibility.

"rickman" wrote in message ...

On 2/16/2015 10:16 PM, Sparky wrote:
Do you happen to have quadruple 300 W audio channels on board?

No, mostly stock old Toyota. Only additional load is Xenon lamps. These
pull
10A total which isn't much for lights...

Maybe I'll upgrade the alternator to a later-model Toyota 70A or such.

What is your current unit rated for 60A?

I replaced the 70A alternator in my truck when a diode opened up. It
was still working, but not enough juice to charge the battery when the
lights were on and I run the headlights all the time, lol. Nothing ever
got fried though.

What is your alternator model number? What year? Mine is a 97 T100 and
I found they changed the alternator in mid model year (around April,
IIRC). Causes a lot of confusion on what is the right model. I tried
finding a replacement diode bridge. *That* was the major change and was
incompatible between the two versions. When looking for parts be sure
to use the VIN to get the right one.

I ended up getting a used alternator and it is running ok now...
although it is in the shop for a clutch. They've ordered two so far.
The first pressure plate "collapsed" whatever that means and the springs
on the second weren't right. They are giving NAPA some hell over this
and are getting an upgraded one to put in my truck. Hope to have it soon.

--

Rick


A 70 amp alternator is not a very large capacity one. I think my old 1999
Mercury Cougar has a stock replacement 110 amp alternator. I burned out the
first one using dual subwoofers and an amp that I added. I took out the
subs and replaced the battery too after replacing the alternator. I live in
central Canada where it gets really cold, so I put a charger on the battery
two or three time during winter to keep the battery at top charge. If you
are making short trips with your vehicle, your battery does not have enough
time to recharge between starts and eventually the charge will keep
decreasing which puts a heavy load on your alternator right after starting
it.

Shaun

On Tue, 24 Feb 2015 10:52:37 -0600, "Shaun"
wrote:



"rickman" wrote in message ...

On 2/16/2015 10:16 PM, Sparky wrote:
Do you happen to have quadruple 300 W audio channels on board?

No, mostly stock old Toyota. Only additional load is Xenon lamps. These
pull
10A total which isn't much for lights...

Maybe I'll upgrade the alternator to a later-model Toyota 70A or such.

Why would you need a bigger alternator than the one that came with the
car? Are you using substantially more current than the car used when
new? How? Only the biggest sound system would use much more current,
and if you have some enormous sound system, or a winch that you use all
the time, stop using those things until you figure out what is wrong
with the car.

My brother bought a new car and the dealer replaced the altenator, the
starter motor, and the battery twice, to make the car start right. But
the dealer guys didn't know what they were doing.

I took it to Sears and they found the problem in less than 5 minutes.
It was a dirty connection between the positive battery cable and the
starter solenoid (which also powered t he starter motor.) It cost
NOTHING in parts to fix, and they charged me nothing to fix it, perhaps
becaue I was buying a new battery, but it would have been very cheap
anyhow. If it's not that connection, it might be another one. You're
battery cables could not have 1.5 ohms resistance, but where they are
connected might.

If a battery post gets hot when you're trying to start the car, there
is a bad connection between that post and the cable connecter that's
attached to it. Hot does not mean it's carrying a lot of electricity.
It means it's having trouble carrying the electricity it needs.
Because of a bad connection that wastes energy making heat.

People spend a lot of time t hinking abou tthe big components and less
time thinking about the wires in between (which I gather you have
checked) and even less time thinking about the connections of the wres
in between. Check them all, especially those that carry substantial
current.

They fixed it, but every time I left the light on for a few hours, the
problem would start again. At firstr I took the cable off and cleaned
everything, like the Sears guy did, but then I learned just ot rotate
the cable end on the stud, 10 or 20^ and then rotate it back.

Finally I got a buzzer that buzzes when I left the headlights or parking
lights on and the problem went a way entirely.

What is your current unit rated for 60A?

I replaced the 70A alternator in my truck when a diode opened up. It
was still working, but not enough juice to charge the battery when the
lights were on and I run the headlights all the time, lol. Nothing ever
got fried though.

What is your alternator model number? What year? Mine is a 97 T100 and
I found they changed the alternator in mid model year (around April,
IIRC). Causes a lot of confusion on what is the right model. I tried
finding a replacement diode bridge. *That* was the major change and was
incompatible between the two versions. When looking for parts be sure
to use the VIN to get the right one.

I ended up getting a used alternator and it is running ok now...
although it is in the shop for a clutch. They've ordered two so far.
The first pressure plate "collapsed" whatever that means and the springs
on the second weren't right. They are giving NAPA some hell over this
and are getting an upgraded one to put in my truck. Hope to have it soon.

"micky" wrote in message ...

On Tue, 24 Feb 2015 10:52:37 -0600, "Shaun"
wrote:



"rickman" wrote in message ...

On 2/16/2015 10:16 PM, Sparky wrote:
Do you happen to have quadruple 300 W audio channels on board?

No, mostly stock old Toyota. Only additional load is Xenon lamps. These
pull
10A total which isn't much for lights...

Maybe I'll upgrade the alternator to a later-model Toyota 70A or such.

Why would you need a bigger alternator than the one that came with the
car? Are you using substantially more current than the car used when
new? How? Only the biggest sound system would use much more current,
and if you have some enormous sound system, or a winch that you use all
the time, stop using those things until you figure out what is wrong
with the car.

My brother bought a new car and the dealer replaced the altenator, the
starter motor, and the battery twice, to make the car start right. But
the dealer guys didn't know what they were doing.

I took it to Sears and they found the problem in less than 5 minutes.
It was a dirty connection between the positive battery cable and the
starter solenoid (which also powered t he starter motor.) It cost
NOTHING in parts to fix, and they charged me nothing to fix it, perhaps
because I was buying a new battery, but it would have been very cheap
anyhow. If it's not that connection, it might be another one. You're
battery cables could not have 1.5 ohms resistance, but where they are
connected might.

If a battery post gets hot when you're trying to start the car, there
is a bad connection between that post and the cable connecter that's
attached to it. Hot does not mean it's carrying a lot of electricity.
It means it's having trouble carrying the electricity it needs.
Because of a bad connection that wastes energy making heat.

People spend a lot of time t hinking abou the big components and less
time thinking about the wires in between (which I gather you have
checked) and even less time thinking about the connections of the wres
in between. Check them all, especially those that carry substantial
current.

They fixed it, but every time I left the light on for a few hours, the
problem would start again. At firstr I took the cable off and cleaned
everything, like the Sears guy did, but then I learned just ot rotate
the cable end on the stud, 10 or 20^ and then rotate it back.

Yup... I've run into that problem too. When it get freezing cold outside,
metal shrinks. If the cable clamps are not tight on the battery, you'll run
into a bad connection at the battery terminal. Temporary fix is to turn the
clamps by hand, if you can - that is the problem. Your car will probably
start after twisting the terminals back and forth, but once you get home -
tighten the bolts with a wrench.

Shaun



Finally I got a buzzer that buzzes when I left the headlights or parking
lights on and the problem went a way entirely.

What is your current unit rated for 60A?

I replaced the 70A alternator in my truck when a diode opened up. It
was still working, but not enough juice to charge the battery when the
lights were on and I run the headlights all the time, lol. Nothing ever
got fried though.

What is your alternator model number? What year? Mine is a 97 T100 and
I found they changed the alternator in mid model year (around April,
IIRC). Causes a lot of confusion on what is the right model. I tried
finding a replacement diode bridge. *That* was the major change and was
incompatible between the two versions. When looking for parts be sure
to use the VIN to get the right one.

I ended up getting a used alternator and it is running ok now...
although it is in the shop for a clutch. They've ordered two so far.
The first pressure plate "collapsed" whatever that means and the springs
on the second weren't right. They are giving NAPA some hell over this
and are getting an upgraded one to put in my truck. Hope to have it soon.