Check a faulty alternator and/or regulator
Yang Yu-shuang 6759
This is about how to check the alternator and regulator in a Toyota Corolla
KE70 1983 Wagon.
The symptom I noticed recently is that the battery is getting weaker and
weaker. This is particularly noticeable in the cold morning as it need a
longer time to crank the engine before it starts. In the last few days,
the battery becomes so weak that it only crank the engine for no more than
3 seconds. So I keep another battery in the car and jump start it each
morning.
I thought this was a battery problem (which was changed 6 monthes ago) until
I noticed that if I turn on the head lights and wind screen wiper, the
alternator puts only 11.5V to the battery. When they are off, the voltage is
about 13V. When the engine is off, the battery voltage is about 12.5V.
All this suggests a faulty alternator or a faulty regulator. It is not
sending out enough current to recharge the battery. However, I don't
know how to isolate which one is faulty so that I could have it repaired
or replaced.
Any suggestions for a further check would be appreciated. As this is VERY
inconvenient to me, please send your reply as soon as possible. It may give
me a big trouble if it stops working completely on the road.
Sam
ya...@mondoe.maths.mu.oz.au
ya...@resmel.bhp.com.au
Sam
Mike Hejl
>
>This is about how to check the alternator and regulator in a Toyota Corolla
>KE70 1983 Wagon.
From your dsescription, the alternator is bad. Take it off the car and take
it to an alternator shop to be checked/repaired. As I recall, the Toy
(Nippondenso?) alternators have internal regulators. Also check the belt.
The alternator should supply approx 13.5v to the battery at idle and a max of
about 14-14.5v at 2000 rpm.
--
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=+
| Mike Hejl @ NEC America Advanced Switching Lab, Irving, TX (214) 518-4763|
| he...@asl.dl.nec.com I don't even speak for myself, much less NEC... |
+=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=+
Pete Rossi
>KE70 1983 Wagon.
>
>I noticed that if I turn on the head lights and wind screen wiper, the
>alternator puts only 11.5V to the battery. When they are off, the voltage is
>about 13V. When the engine is off, the battery voltage is about 12.5V.
>All this suggests a faulty alternator or a faulty regulator. It is not
>sending out enough current to recharge the battery. However, I don't
>know how to isolate which one is faulty so that I could have it repaired
>or replaced.
An ammeter will tell you EXACTLY what is going on!!
YOU CAN SPEND $15,000 - $50,000 for an NEW car these days... WHY WHY WHY
can't they include a simple **AMMETER** on them??? WHAT does a VOLTMETER
tell you??? NOTHING!!! (or very little)
A DEAD battery (one that will not start a car) may still show 12-13 VOLTS.
Hey, you can put 8 "D" batteries in your car and the meter will still show
12-13 volts but it will never start your car :-)
An ammeter will tell you exactly what the alternator/regulator/battery is
doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
will start to show them and long before you have ruined your battery from
over or under charging.
Is it me? Am I missing something? Why did they stop putting ammeters in cars?
=================================================================
Pete Rossi - WA3NNA ro...@gvlf8.gvl.unisys.com
Paramax Systems Corporation - a Unisys Company
Electronic Systems - Valley Forge Labs - Paoli, Pennsylvania
=================================================================
Jonathan Bruce Hacker
>An ammeter will tell you exactly what the alternator/regulator/battery is
>doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
>will start to show them and long before you have ruined your battery from
>over or under charging.
>Is it me? Am I missing something? Why did they stop putting ammeters in
>cars?
An ammeter requires high currents to be carried to the gauge and
back with thick wire, whereas a voltmeter can tap into any part of
the electrical system with no special extra wiring involved.
Guess which costs less to install????? Guess which gauge
bean counters in the accounting department will like better
at the auto companies???
--
Jon Hacker
Caltech, Pasadena CA
hac...@tumbler-ridge.caltech.edu
Graham Sewell
>An ammeter will tell you EXACTLY what is going on!!
>YOU CAN SPEND $15,000 - $50,000 for an NEW car these days... WHY WHY WHY
>can't they include a simple **AMMETER** on them??? WHAT does a VOLTMETER
>tell you??? NOTHING!!! (or very little)
>An ammeter will tell you exactly what the alternator/regulator/battery is
>doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
>will start to show them and long before you have ruined your battery from
>over or under charging.
>Is it me? Am I missing something? Why did they stop putting ammeters in cars?
One obvious problem is the range of currents that need to be monitored.
If the current is measured during cranking of the starter, the I would
expect a reading of around 200 amps. However, during normal operation
(lights, rear demister, ignition, radio, etc), I would expect around 20
amps. For a meter to be accurate at these ranges, it would need to be a
multirange digital meter. Otherwise, it would be useless at one extreme
or the other.
--
Graham Sewell Tel +44 71 728 4851
Unix TP and Database Unit Fax +44 71 728 4883
PP506, Lion House, 72-75 Red Lion St, LONDON. WC1R 4RT
g...@btcase.bt.co.uk
Roberto L. Landrau
>>An ammeter will tell you exactly what the alternator/regulator/battery is
>>doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
>>will start to show them and long before you have ruined your battery from
>>over or under charging.
>>Is it me? Am I missing something? Why did they stop putting ammeters in cars?
I have wondered the same thing, too.
In article <1992Apr30.0...@btcase.bt.co.uk>
g...@btcase.bt.co.uk (Graham Sewell) writes:
>One obvious problem is the range of currents that need to be monitored.
>If the current is measured during cranking of the starter, the I would
>expect a reading of around 200 amps. However, during normal operation
>(lights, rear demister, ignition, radio, etc), I would expect around 20
>amps. For a meter to be accurate at these ranges, it would need to be a
>multirange digital meter. Otherwise, it would be useless at one extreme
>or the other.
There is a way around it. You can have one wire going from the
battery to the starter (or solenoid) and another wire going to
everything else. You can connect your ammeter to the second wire.
That way you will have the net current in or out of the battery minus
the starter current.
--
The opinions stated above are not necessarily my employer's.
----------------------------------------------------------------
Roberto L. Landrau KC1YP lan...@mitre.org r...@linus.mitre.org
The MITRE Corporation Bedford, MA 01730 r...@linus.UUCP
Douglas S. Rand
There is a way around it. You can have one wire going from the
battery to the starter (or solenoid) and another wire going to
everything else. You can connect your ammeter to the second wire.
That way you will have the net current in or out of the battery minus
the starter current.
Absolutely. This is *the* way that an ammeter is wired into a car.
You would never want to have it in the starter circuit. But I
don't like ammeters, they require heavy gauge wire and introduce new
places for electrical problems to occur.
A voltmeter will tell you if the battery is charged or partially
discharged and whether the charging system is working correctly,
and a voltmeter only requires a small piece of wire to power.
As I recall, a car's electrical system runs at 13.8 V when the
engine is running and a fully charged battery is 12 V. So look
at the voltmeter before starting the engine and while the car is
running and you should get a good idea of the charging system's
condition and the battery charge.
While it is true, as a previous poster mentioned, that a voltmeter
will register 12 V with little capacity in the battery, it is also
true that a ammeter can still register low amps with a low capacity
(but charged) battery that will leave you stranded in the dead of
winter.
--
Douglas S. Rand
Internet: <d...@luke.mitre.org>
Disclaimer: I never agree with MITRE, but that doesn't matter anymore
Amateur Radio: KC1KJ
Bob Wilson
>If the current is measured during cranking of the starter, the I would
>expect a reading of around 200 amps. However, during normal operation
>(lights, rear demister, ignition, radio, etc), I would expect around 20
>amps. For a meter to be accurate at these ranges, it would need to be a
>multirange digital meter. Otherwise, it would be useless at one extreme
>or the other.
>
>--
>Graham Sewell Tel +44 71 728 4851
>Unix TP and Database Unit Fax +44 71 728 4883
>PP506, Lion House, 72-75 Red Lion St, LONDON. WC1R 4RT
>g...@btcase.bt.co.uk
That's why a properly installed ammeter DOESN'T show the current to
the starter except the solenoid, just the current drawn by everything
else minus the charging current from the alternator. After all most
cars until fairly recently DID have ammeters, so it can't require
digital electronics! (In any case you wouldn't want to run the
hundreds of amps to the starter windings through any extra wire with
the resulting voltage drop and requirement for even heavier wire!)
Bob Wilson
wil...@math.wisc.edu
Pete Rossi
>ro...@gvlf8-m.gvl.unisys.com (Pete Rossi) writes:
>>Is it me? Am I missing something? Why did they stop putting ammeters in
>>cars?
>
>An ammeter requires high currents to be carried to the gauge and
>back with thick wire, whereas a voltmeter can tap into any part of
>the electrical system with no special extra wiring involved.
>
>Guess which costs less to install????? Guess which gauge
>bean counters in the accounting department will like better
>at the auto companies???
You do not need heavy wires running to the meter. You use a meter shunt.
I my installation I use the negative battery cable as the meter shunt and
run two 22 gauge wires to the meter.
In article <1992Apr30.0...@btcase.bt.co.uk>
g...@btcase.bt.co.uk (Graham Sewell) writes:
>One obvious problem is the range of currents that need to be monitored.
>If the current is measured during cranking of the starter, the I would
>expect a reading of around 200 amps. However, during normal operation
>(lights, rear demister, ignition, radio, etc), I would expect around 20
>amps. For a meter to be accurate at these ranges, it would need to be a
>multirange digital meter. Otherwise, it would be useless at one extreme
>or the other.
Since normally you don't care about the starter current, you can use the
wire between the alternator and the battery as the meter shunt. This way
you see only the current flow involved with running the accessories and
charging the battery.
My ammeter is roughly 50 amps. It is sensitive enough to see things
like the turn signals flashing, even the dome light when I open the
door. It measures total current including the starter so it will peg
in the negative direction when I start the car, but not hard enough to
hurt the meter.
-----------
After further thought/discussion, I have come to the conclusion that
what is *really* needed is BOTH and ammeter and voltmeter. The ammeter
will show the condition/status of the alternator/regulator and the
voltmeter will show the condition/status of the battery.
There is some overlap but with both meters there would be no question as
to what was going on. Of course the $$$ involved it would never happen
unless you did it yourself.
Mike Hejl
>
>As I recall, a car's electrical system runs at 13.8 V when the
>engine is running and a fully charged battery is 12 V. So look
In most cases, the alternator/regulator supplies about 13.5V at idle and
increases to about 14-14.5V max as the engine speed increases. The max
reading is usually dependant on ambient temp, especially for older cars
with points-type regulators and also depends on the batteries charge
condition. This is more easily visible with an with an analog or digital VMM
because most instrument cluster guages have dampener circuitry. Stand-alone
battery voltage is typically 12.5V.
>While it is true, as a previous poster mentioned, that a voltmeter
>will register 12 V with little capacity in the battery, it is also
>true that a ammeter can still register low amps with a low capacity
>(but charged) battery that will leave you stranded in the dead of
>winter.
When cranking, even a good battery will drop to about 10-11V. A bad battery,
say with a dead cell, may register a full 12 volts with no load but drop to
miniscule voltage (<2V) under load. So, what is the advantage of an ammeter?
Overall, a voltmeter is just as informative, if not more so, about the
charging system as an ammeter is. The voltmeter also has added reliability
compared to the ammeter considering that the ammeter must be in series with
the vehicle's supply current (except for the starter) rather than parallel.
BTW, the professional "battery load testers" contain esentially heater coils
to draw large current from the battery. Output is indicated with a
voltmeter, not an ammeter.
John R. Caruso
> Is it me? Am I missing something? Why did they stop putting ammeters in cars?
>
Because the only maintenance that most people do is to put
gas in their cars - for that you don't need an ammeter.
jRc
Chris O'Neill
>A voltmeter will tell you if the battery is charged or partially
>discharged and whether the charging system is working correctly,
>and a voltmeter only requires a small piece of wire to power.
>
>As I recall, a car's electrical system runs at 13.8 V when the
>engine is running and a fully charged battery is 12 V. So look
>at the voltmeter before starting the engine and while the car is
>running and you should get a good idea of the charging system's
>condition and the battery charge.
While the engine is running, the battery voltage goes up to 13.8 or whatever
the charging system runs it to regardless of whether the battery had good or
weak capacity. A better indication is if the battery voltage goes down much if
the engine doesn't start. You can't necessarily arrange this without
disconnecting the ignition or something but if you can crank the engine without
starting it, the voltmeter will give you a good indication of battery condition
by observing the voltage before and after cranking.
>While it is true, as a previous poster mentioned, that a voltmeter
>will register 12 V with little capacity in the battery, it is also
>true that a ammeter can still register low amps with a low capacity
>(but charged) battery that will leave you stranded in the dead of
>winter.
Yes. I guess generally the ammeter just tells you whether the charging sustem
is working properly but a voltmeter can tell you more about the battery.
Chris O'Neill
Kevin Brown
>
>>An ammeter will tell you EXACTLY what is going on!!
>
>>YOU CAN SPEND $15,000 - $50,000 for an NEW car these days... WHY WHY WHY
>>can't they include a simple **AMMETER** on them??? WHAT does a VOLTMETER
>>tell you??? NOTHING!!! (or very little)
>
>>An ammeter will tell you exactly what the alternator/regulator/battery is
>>doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
>>will start to show them and long before you have ruined your battery from
>>over or under charging.
>
>>Is it me? Am I missing something? Why did they stop putting ammeters in cars?
>
>One obvious problem is the range of currents that need to be monitored.
>If the current is measured during cranking of the starter, the I would
>expect a reading of around 200 amps. However, during normal operation
>(lights, rear demister, ignition, radio, etc), I would expect around 20
>amps. For a meter to be accurate at these ranges, it would need to be a
>multirange digital meter. Otherwise, it would be useless at one extreme
>or the other.
So use a logarithmic scale. When the current values are high, you don't
need a great deal of resolution. When the current values are low, on the
other hand, you probably want better resolution. A log scale will get you
both...
With the inductive pickup technology we have these days, building a beast
like this that doesn't have to take the actual current being drawn is easy.
I agree with Pete. The ammeter is much more useful, and it makes a lot more
sense to put one in. Apparently, the voltmeter is much cheaper to
manufacture...
>Graham Sewell Tel +44 71 728 4851
--
Kevin Brown (ke...@taronga.taronga.com)
pc
>In article <1992Apr30.0...@btcase.bt.co.uk> g...@btcase.bt.co.uk (Graham Sewell) writes:
>>ro...@gvlf8-m.gvl.unisys.com (Pete Rossi) writes:
>>
>>>An ammeter will tell you EXACTLY what is going on!!
>>
>>>doing. It also can identify problems *LONG* BEFORE the stupid voltmeter
>>>will start to show them and long before you have ruined your battery from
>>>over or under charging.
>>
>>>Is it me? Am I missing something? Why did they stop putting ammeters in cars?
>>
>>One obvious problem is the range of currents that need to be monitored.
>>If the current is measured during cranking of the starter, the I would
>>expect a reading of around 200 amps. However, during normal operation
>>(lights, rear demister, ignition, radio, etc), I would expect around 20
>>amps. For a meter to be accurate at these ranges, it would need to be a
>>multirange digital meter. Otherwise, it would be useless at one extreme
>>or the other.
>
>So use a logarithmic scale. When the current values are high, you don't
>need a great deal of resolution. When the current values are low, on the
>other hand, you probably want better resolution. A log scale will get you
>both...
You don't really need to measure the current that the starter draws,
and have never seen an ammeter in a car that does. A battery has
at least two wires on the positive terminal. One huge wire that
carries starter current, and another wire (8-10 gauge) that carries
current to all the accessories (lights, radio, ignition, etc) as
well as the current that charges the battery. It is this line
that you want an ammeter connected to. This way, the ammeter
tells you if the battery is charging or discharging. With a charged
battery, and a properly functioning alternator/regulator, you
should see a reading of 0 Amps on the ammeter. If the alternator
dies, the battery will be supplying all the current, and you
will see the discharge current on the meter.
pc
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