Adding voltmeter to car

[Andy]

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks



--

The voltmeter web pages include:
http://www.carbuyingtips.com/jumpstart.htm
http://www.repairfaq.org/ELE/F_Car_Battery.html
http://www.inct.net/~autotips/batterm.htm

 

[hob]

"Andy" <nomail@nomail.com> wrote in message
news:Xns97A4E3D492A8F74C1H4@127.0.0.1...

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Auto voltmeter - also known as the "somebody stole your battery" gauge.
Because other than a missing battery, it basically tells you, too late, what
you already know - weak lights, poor start, bad battery, etc.

An in-dash ammeter, on the other hand, tells you before you are stranded if
you are charging or discharging the battery and how much is going in or
out, and the amps are if steady or fluctuating , all of which can be used as
an indicator for the condition of the alternator and battery, the
connections, and switch-off draining.

Don't waste your time putting in a voltmeter.

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks



--

The voltmeter web pages include:
http://www.carbuyingtips.com/jumpstart.htm
http://www.repairfaq.org/ELE/F_Car_Battery.html
http://www.inct.net/~autotips/batterm.htm

 

[chuck]

Andy wrote:

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks



Don't bother with a voltmeter. A far better investment is a set of

jumper cables.

Chuck

 

[SQLit]

"Andy" <nomail@nomail.com> wrote in message
news:Xns97A4E3D492A8F74C1H4@127.0.0.1...

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks



--

The voltmeter web pages include:
http://www.carbuyingtips.com/jumpstart.htm
http://www.repairfaq.org/ELE/F_Car_Battery.html
http://www.inct.net/~autotips/batterm.htm

volt meters have nothing to do with the status of the battery. sure they
will show the amount of voltage produced. most are highly in accurate.

talk to a good mechanic

 

[Gary Schafer]

On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter. A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

A properly running alternator should raise the battery voltage to
around 14 to 14.2 volts. Some cars may run as high as 14.4 volts. Any
higher and you can suspect a problem with the regulator.
If the voltage fails to come up this high you can suspect a problem in
the alternator, shorted diode etc.

A voltmeter can also tell you if the alternator is capable of putting
out enough current. As you turn more things on, lights,
air-conditioning etc. the alternator should be capable of maintaining
the voltage at the 14 volt range. If the voltage drops well below that
range you can look for problems.

After the car has been shut down for a period of time you can read the
battery voltage to tell you the approximate charge on the battery by
the resting voltage.

You can also watch how far the voltage drops when turning on
headlights etc. with the engine not running. If the voltage drops way
off you may have a battery that is developing a high resistance,
battery is dying.

You can also watch how far the voltage drops when starting the car.
This is another indication of battery condition.

None of these things can be done with an ammeter.
An ammeter will only tell you if the battery is being charged or
discharged at a particular time. If the battery has a high resistance
or is fully charged you can not tell the difference with an ammeter.

About the only thing an ammeter is good for is to let you know that
the battery is not being discharged while the car is running.

The voltmeter should be connected directly to the battery terminals
with its own leads for the above indications to be meaningful. Put a
small fuse in the hot lead right at the battery to protect the wires.

Regards
Gary

 

[hob]

"Gary Schafer" <gaschafer@comcast.net> wrote in message
news:gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com...

On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter. A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

A properly running alternator should raise the battery voltage to
around 14 to 14.2 volts. Some cars may run as high as 14.4 volts. Any
higher and you can suspect a problem with the regulator.
If the voltage fails to come up this high you can suspect a problem in
the alternator, shorted diode etc.n

or more usually, the connections on the dash. (like my three cars).

A voltmeter can also tell you if the alternator is capable of putting
out enough current.

Just kind turning on the fan and watching the lights dim, but the voltmeter
is not nearly as accurate.

As you turn more things on, lights,

air-conditioning etc. the alternator should be capable of maintaining
the voltage at the 14 volt range.

granted, the voltmeter tells you that the computer says to raise the field -
but it does not say if anything is being generated and/or sent to the
battery.
- kind of like my jeep did two weeks back, where the voltmeter said all
was ok - and the battery had just enough to turn it over twice.
And next time it didn't start with 12 volts shown, so after it was running
after a jump (voltmeter had said zero) - voltmeter went to 14.4 and then
went down to 13.5 after driving. But the ammeter said it was sending 10
amps into a battery. At the shop, the disconnected battery had all of 11
volts and wouldn't take a charge. Voltmeter was reading alternator output
voltage, not energy going into the battery. The battery had the capacity of
a AAA, and tyhe voltmeter said 12 volts.

If the voltage drops well below that

range you can look for problems.

Just like a low battery does - turn the key and get a click, but the
voltmeter is not as accurate

After the car has been shut down for a period of time you can read the
battery voltage to tell you the approximate charge on the battery by
the resting voltage.

You can also watch how far the voltage drops when turning on
headlights etc. with the engine not running. If the voltage drops way
off you may have a battery that is developing a high resistance,
battery is dying.

Of course, turning the key after that test also tells you you need a tow and
a battery.
An indication which helps a lot when you are driving - that is also
indicated by the car not starting.

You can also watch how far the voltage drops when starting the car.
This is another indication of battery condition.

None of these things can be done with an ammeter.

And nor does one want to - and unlike voltmeters that tell you voltage level
rather than energy transfer, ammeters only check the battery input and
output running and motor off, and the charging circuit, the starting
circuit, alternator output, and cable/connection/belt condition running. You
know, the energy the vehicle actually uses.

An ammeter will only tell you if the battery is being charged or
discharged at a particular time. If the battery has a high resistance
or is fully charged you can not tell the difference with an ammeter.

Sorry, yes you can. Same symptoms as with the voltmeter.

You know, there's a reason so many expereinced people in
alt.engineering.elect jumped on the thread to roundly condemn voltmeters as
next to worthless-

(BTW, the reason ammeters were removed was to save weight to get fleet
mileage up - an ammeter takes a ballast resistor and heavy cables and
connectors. A voltmeter takes an inch of circuitboard foil. And, anything a
voltmeter does is also sensed by the diagnostics and flagged, on my
vehicles)

About the only thing an ammeter is good for is to let you know that
the battery is not being discharged while the car is running.

The voltmeter should be connected directly to the battery terminals
with its own leads for the above indications to be meaningful. Put a
small fuse in the hot lead right at the battery to protect the wires.

Regards
Gary

 

[Rheilly Phoull]

hob wrote:

"Gary Schafer" <gaschafer@comcast.net> wrote in message
news:gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com...
On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter. A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

A properly running alternator should raise the battery voltage to
around 14 to 14.2 volts. Some cars may run as high as 14.4 volts. Any
higher and you can suspect a problem with the regulator.
If the voltage fails to come up this high you can suspect a problem
in the alternator, shorted diode etc.n

or more usually, the connections on the dash. (like my three cars).


A voltmeter can also tell you if the alternator is capable of putting
out enough current.

Just kind turning on the fan and watching the lights dim, but the
voltmeter is not nearly as accurate.

As you turn more things on, lights,
air-conditioning etc. the alternator should be capable of maintaining
the voltage at the 14 volt range.

granted, the voltmeter tells you that the computer says to raise the
field - but it does not say if anything is being generated and/or
sent to the battery.
- kind of like my jeep did two weeks back, where the voltmeter said
all was ok - and the battery had just enough to turn it over twice.
And next time it didn't start with 12 volts shown, so after it was
running after a jump (voltmeter had said zero) - voltmeter went to
14.4 and then went down to 13.5 after driving. But the ammeter said
it was sending 10 amps into a battery. At the shop, the disconnected
battery had all of 11 volts and wouldn't take a charge. Voltmeter
was reading alternator output voltage, not energy going into the
battery. The battery had the capacity of a AAA, and tyhe voltmeter
said 12 volts.

If the voltage drops well below that
range you can look for problems.


Just like a low battery does - turn the key and get a click, but the
voltmeter is not as accurate

After the car has been shut down for a period of time you can read
the battery voltage to tell you the approximate charge on the
battery by the resting voltage.

You can also watch how far the voltage drops when turning on
headlights etc. with the engine not running. If the voltage drops way
off you may have a battery that is developing a high resistance,
battery is dying.

Of course, turning the key after that test also tells you you need a
tow and a battery.
An indication which helps a lot when you are driving - that is also
indicated by the car not starting.


You can also watch how far the voltage drops when starting the car.
This is another indication of battery condition.

None of these things can be done with an ammeter.

And nor does one want to - and unlike voltmeters that tell you
voltage level rather than energy transfer, ammeters only check the
battery input and output running and motor off, and the charging
circuit, the starting circuit, alternator output, and
cable/connection/belt condition running. You know, the energy the
vehicle actually uses.

An ammeter will only tell you if the battery is being charged or
discharged at a particular time. If the battery has a high resistance
or is fully charged you can not tell the difference with an ammeter.

Sorry, yes you can. Same symptoms as with the voltmeter.

You know, there's a reason so many expereinced people in
alt.engineering.elect jumped on the thread to roundly condemn
voltmeters as next to worthless-

(BTW, the reason ammeters were removed was to save weight to get fleet
mileage up - an ammeter takes a ballast resistor and heavy cables and
connectors. A voltmeter takes an inch of circuitboard foil. And,
anything a voltmeter does is also sensed by the diagnostics and
flagged, on my vehicles)

About the only thing an ammeter is good for is to let you know that
the battery is not being discharged while the car is running.

The voltmeter should be connected directly to the battery terminals
with its own leads for the above indications to be meaningful. Put a
small fuse in the hot lead right at the battery to protect the wires.

Regards
Gary

So says Hob

I reckon both have uses and the interpretation is only a problem to the
inexperienced.
Each to their own IMHO I like both but if had to choose would go the
voltmeter.


--
Regards ......... Rheilly Phoull

 

[Conor]

In article <gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com>, Gary Schafer
says...

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter.

Spot the pillock who knows fuck all about car electrics.

A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

No it won't. A completely fucked battery can show >12v but still not be
able to provide enough current to turn an engine over.

Think I'm wrong? Why are batteries tested with a drop meter?


--
Conor,

Same shit, different day.

 

[Conor]

In article <443f6aaa$0$32103$5a62ac22@per-qv1-newsreader-
01.iinet.net.au>, Rheilly Phoull says...

Each to their own IMHO I like both but if had to choose would go the
voltmeter.

walks away shaking head

OK then....



--
Conor,

Same shit, different day.

 

[Ed]

hob wrote:

"Gary Schafer" <gaschafer@comcast.net> wrote in message
news:gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com...

On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:


I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashmoard voltmeter".

Is a voltmeter actually all that useful to see tjings like what
the condition the battery is in and how the battery copes and how
it is charging?

Can I permanently connect my cheap handheld digital voltmeter to
the car battery. I would then mount the meter permanently on the
dashboard.

Is there a real danger that the meter will get damaged by various
current or voltage surges? Is it good enough protection to have a
quick blow fuse in line with the test lead going to the positive
terminal?

Thanks

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter. A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

A properly running alternator should raise the battery voltage to
around 14 to 14.2 volts. Some cars may run as high as 14.4 volts. Any
higher and you can suspect a problem with the regulator.
If the voltage fails to come up this high you can suspect a problem in
the alternator, shorted diode etc.n


or more usually, the connections on the dash. (like my three cars).


A voltmeter can also tell you if the alternator is capable of putting
out enough current.


Just kind turning on the fan and watching the lights dim, but the voltmeter
is not nearly as accurate.

If you were to log voltage over time it would tell you a whole lot more
than current.

As you turn more things on, lights,

air-conditioning etc. the alternator should be capable of maintaining
the voltage at the 14 volt range.


granted, the voltmeter tells you that the computer says to raise the field -

Computer? ignition simply being ON energises the armature field. I've
not seen any computer input needed here?

but it does not say if anything is being generated and/or sent to the
battery.

Wrong! It shows exactly this. A car battery will not rest at 14v.
therefore if your measuring 14v @ battery you know without any question
what so ever that the battery is being charged.

- kind of like my jeep did two weeks back, where the voltmeter said all
was ok - and the battery had just enough to turn it over twice.

High internal resistance, you'll again see this by cranking the engine
and the battery voltage will fall extremely low, again an ammeter will
not be able to show this.

And next time it didn't start with 12 volts shown, so after it was running
after a jump (voltmeter had said zero) - voltmeter went to 14.4 and then
went down to 13.5 after driving. But the ammeter said it was sending 10
amps into a battery. At the shop, the disconnected battery had all of 11
volts and wouldn't take a charge.

Again what you have said shows a tired and worn battery
(cracked/sulphated cells) and can be easily demonstrated with a load
(cranking) and a voltmeter.

Voltmeter was reading alternator output
voltage, not energy going into the battery. The battery had the capacity of
a AAA, and tyhe voltmeter said 12 volts.

Your completely reading this wrong. The fact that the voltmeter was
working and correctly showed your system voltage showed you immediately
where the problem was (battery) Process of elimination. You see the
symptoms - battery voltage is ok, charge voltage is ok, yet not enough
current to crank = dead battery!

If the voltage drops well below that

range you can look for problems.



Just like a low battery does - turn the key and get a click, but the
voltmeter is not as accurate

Yes it is!

After the car has been shut down for a period of time you can read the
battery voltage to tell you the approximate charge on the battery by
the resting voltage.

You can also watch how far the voltage drops when turning on
headlights etc. with the engine not running. If the voltage drops way
off you may have a battery that is developing a high resistance,
battery is dying.


Of course, turning the key after that test also tells you you need a tow and
a battery.
An indication which helps a lot when you are driving - that is also
indicated by the car not starting.

If you do this test and then you are unable to start, like Gary said the

battery is dying. Clearly if you felt this was such a risk you would not
make this test unless you had another way to start the car. There are
thousands of cars on the road with batteries that have nearly no reserve
capacity, you need surprisingly little to be able to start a car, but
you only really notice after you have left your lights on for a few mins
only to discover you cannot start again!

You can also watch how far the voltage drops when starting the car.
This is another indication of battery condition.

None of these things can be done with an ammeter.


And nor does one want to - and unlike voltmeters that tell you voltage level
rather than energy transfer, ammeters only check the battery input and
output running and motor off, and the charging circuit, the starting
circuit, alternator output, and cable/connection/belt condition running. You
know, the energy the vehicle actually uses.

No offence I think your blinded by your own ignorance. Everything you
say there can be shown better with a volt meter. You say that an ammeter
shows the "cable/connection/belt condition running" ok so what exactly
should the current be when its all correct? I can tell you a voltage
that I know would be right but since once the car has started and the
battery has regained its lost charge (not long under usual conditions)
how an ammeter between the battery and anything else would show nothing
useful at all, apart from a varying and often small charge. (which again
can be shown much better with a voltmeter showing around 14v)

Lets assume you connect it in series with the alternator. An instant
disadvantage is the fact that you now have introduced more resistance to
the circuit, so you slightly loose efficiency (fact of physics and is
how all ammeter works) You could be running in daylight conditions
lights off and little load, you could be running at night in the rain
lights on heaters on fans on etc etc and again you see load. Great. So
are you actually going to be able to see what current is right or wrong
as fast as I can read a voltmeter and go PROBLEM or not?!

An ammeter will only tell you if the battery is being charged or
discharged at a particular time. If the battery has a high resistance
or is fully charged you can not tell the difference with an ammeter.


Sorry, yes you can. Same symptoms as with the voltmeter.

Nope not so. A battery with high internal resistance with an ammeter all
you would see is a charged battery, that assumption made by the fact
that there will be little charge current.

You know, there's a reason so many expereinced people in
alt.engineering.elect jumped on the thread to roundly condemn voltmeters as
next to worthless-

Using other peoples posts to back up your own is pretty pointless.

(BTW, the reason ammeters were removed was to save weight to get fleet
mileage up - an ammeter takes a ballast resistor and heavy cables and
connectors. A voltmeter takes an inch of circuitboard foil. And, anything a
voltmeter does is also sensed by the diagnostics and flagged, on my
vehicles)

The main reason they were removed as they are not needed as people
wouldn't know what's right or wrong, and alternators have simply removed
the need. Where as voltage meters are much more common, because that
actually shows you something useful.

Further if current meters are such a good way of knowing the status of
charge of a battery or condition of a system then intelligent battery
chargers would measure and monitor battery charge by current - which
they don't. Virtually every type of charger stops when a certain voltage
is met, and has no concern with current other than the fact to limit it
to prevent damage to cells.

 

[Chris Whelan]

Ed wrote:
[...]

Computer? ignition simply being ON energises the armature field. I've
not seen any computer input needed here?

Then, with the greatest of respect, you don't know much about how a modern
car's charging system works.....

Chris

--
Remove prejudice to reply.

 

[Ed]

Chris Whelan wrote:

Ed wrote:
[...]


Computer? ignition simply being ON energises the armature field. I've
not seen any computer input needed here?


Then, with the greatest of respect, you don't know much about how a modern
car's charging system works.....

Chris

Nonsense. With the ignition on ON (NOT accessories) the alternator
usually via the 'battery' combination meter on the dash will be provided
12v to its armature windings.

 

[Ed]

Conor wrote:

In article <gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com>, Gary Schafer
says...


If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter.


Spot the pillock who knows fuck all about car electrics.


A voltmeter will tell you much more
about the battery and the charging system than an ammeter.


No it won't. A completely fucked battery can show >12v but still not be
able to provide enough current to turn an engine over.

Think I'm wrong? Why are batteries tested with a drop meter?

Oh well done, but if the car starts fine an ammeter is no help to show
the condition of a charge system.

 

[Ed]

Conor wrote:

In article <443f6aaa$0$32103$5a62ac22@per-qv1-newsreader-
01.iinet.net.au>, Rheilly Phoull says...


Each to their own IMHO I like both but if had to choose would go the
voltmeter.


walks away shaking head

What?

Ok so you have a car come in with a charging problem.

Do you:

1, pick up your ammeter and proceed to test with this.

or

2, pick up a volt meter and proceed to test with this.

 

[Michael A. Terrell]

Ed wrote:

Conor wrote:
In article <gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com>, Gary Schafer
says...


If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter.


Spot the pillock who knows fuck all about car electrics.


A voltmeter will tell you much more
about the battery and the charging system than an ammeter.


No it won't. A completely fucked battery can show >12v but still not be
able to provide enough current to turn an engine over.

Think I'm wrong? Why are batteries tested with a drop meter?

Oh well done, but if the car starts fine an ammeter is no help to show
the condition of a charge system.

Sure it is. If the battery isn't taking a proper charge it will show
up in the first couple seconds after the engine starts. There should be
a high charging current as soon as the alternator comes up to full
speed, then drop back to nominal as soon as the battery returns to fully
charged. I've had fairly new batteries be almost fully discharged, but
I managed to jump start the vehicle and drive for an hour to work as it
fully recharges the battery and slowly drops back to nominal while the
battery terminal's voltage doesn't change more than a few millivolts.
After all, a car alternator is a constant voltage charger.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Chris Whelan]

Ed wrote:

[...]

What?

Ok so you have a car come in with a charging problem.

Do you:

1, pick up your ammeter and proceed to test with this.

or

2, pick up a volt meter and proceed to test with this.

Yes, but there is a huge difference between testing for a fault in a
workshop, and providing something meaningful for the driver to use to
monitor the health of his vehicle.

IME, even a red "No charge" light is too much for some drivers to
comprehend...

Chris

--
Remove prejudice to reply.

 

[Boris Mohar]

On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:

I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashboard voltmeter".

I added a wide range 270° battery voltmeter in my first Volvo. It would
read from 8 to 18 volts. One time on a long trip through Colorado I noticed
that it was reading over 16Volts. It was a very hot day and battery voltage
coefficient being negative, the reading should have been around 13V. It
turned out that the regulator had shorted out and was dumping the generator
to the battery. I turned on every electrical load and drove in the highest
gear over to the dealer.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

[Jamie]

Boris Mohar wrote:

On Thu, 13 Apr 2006 22:23:47 +0100, Andy <nomail@nomail.com> wrote:


I am in the UK and have a 1.3 litre Mazda which is over 10 years
old.

I have been reading a few web pages which made reference to the
reader's car which "may have a dashboard voltmeter".



I added a wide range 270° battery voltmeter in my first Volvo. It would
read from 8 to 18 volts. One time on a long trip through Colorado I noticed
that it was reading over 16Volts. It was a very hot day and battery voltage
coefficient being negative, the reading should have been around 13V. It
turned out that the regulator had shorted out and was dumping the generator
to the battery. I turned on every electrical load and drove in the highest
gear over to the dealer.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place


did you happen to smell a strange odor under the hood ? just don't

light up while looking under the hood! )


--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[Gary Schafer]

On Fri, 14 Apr 2006 12:15:42 +0100, Conor <conor.turton@gmail.com>
wrote:

In article <gc0u32t4gc55rpqe3pjfuvvev1rhlk4vl4@4ax.com>, Gary Schafer
says...

If I had only one instrument to connect to the car to watch the
battery it would be a voltmeter.

Spot the pillock who knows fuck all about car electrics.

A voltmeter will tell you much more
about the battery and the charging system than an ammeter.

No it won't. A completely fucked battery can show >12v but still not be
able to provide enough current to turn an engine over.

Think I'm wrong? Why are batteries tested with a drop meter?

Actually if a battery only shows "12 volts" it is near dead!

If you will take note, when a battery is tested with a "drop meter" it
actually has a voltmeter in the instrument! Simple ones have ONLY a
voltmeter! More sophisticated ones have a voltmeter and an ammeter.

The idea of the test is to see how well the VOLTAGE holds up on the
battery with a given load placed on it. With the simple testers it is
a given amount of resistance placed on the battery for a certain
length of time while monitoring the battery voltage.

If the resting voltage of lthe battery, no load, shows 12.6 to 12.8
volts that is an indication of a fully charged battery. If that vltage
drops significantly with the load test then the battery probably has a
high internal resistance. If the resting voltage is near 12 volts the
battery is in need of charging.

With the better units which contain an adjustable load, ammeter and
voltmeter the load is adjusted to see how much current the battery can
supply before the voltage drops to a certain level. Without knowing
the voltage the rest of the test is pretty much meaningless.

If you read my first post again, carefully, you will see where I
explain (with the engine off) how to watch the voltmeter in the car
while turning on accessory items and watching how far the voltage
drops to give you an indication of battery health. Also how much the
voltage drops when starting.
This does essentially the test that is done with a load tester.

One important point about use of the voltmeter, it needs to come
directly from the battery terminals and not be connected into wiring
that also serves other things like lights etc. Otherwise you will not
get a true reading of battery voltage when turning those other things
on as it will also read the voltage drop in the wiring and not the
true battery voltage.

Also note that some factory installed voltmeters are wired as noted
above and some are also very poor quality meters.

You can have all the instruments you can manage to gather but if you
don't know how to interpret them they do little good.

Regards
Gary

 

[Douglas Payne]

Ed wrote:

What?

Ok so you have a car come in with a charging problem.

Do you:

1, pick up your ammeter and proceed to test with this.

or

2, pick up a volt meter and proceed to test with this.

3, get all in a huffy and go and post rude words on some newsgroups.

(c:

--
Douglas