Measuring the meter

I've got an old car that sees sporadic use from a new(learning) driver. After
sitting unused for ~3 weeks it had a low battery, but charged right up
overnight. I want to leave a 9-15v horizontal panel meter dangling from the
12v cigarette lighter outlet in order to monitor battery health. Problem is
that the outlet is unswitched, meter is deflected even when the ignition is
off.

Can anyone point me to a procedure for measuring or calculating the current
drain from the meter?

The meter says CK-250A, Taiwan and it is very small made from clear plastic.
Looks like it was manufactured for inclusion into a 12v battery charger. I
bought it at an old industrial liquidator outlet - now closed.

TIA

I've got an old car that sees sporadic use from a new(learning) driver.
After sitting unused for ~3 weeks it had a low battery, but charged right up
overnight. I want to leave a 9-15v horizontal panel meter dangling from the
12v cigarette lighter outlet in order to monitor battery health. Problem is
that the outlet is unswitched, meter is deflected even when the ignition is
off.

Can anyone point me to a procedure for measuring or calculating the current
drain from the meter?

The meter says CK-250A, Taiwan and it is very small made from clear plastic.
Looks like it was manufactured for inclusion into a 12v battery charger. I
bought it at an old industrial liquidator outlet - now closed.

TIA

How about putting a potentiometer in series with the meter +.
Adjust the potentiometer until the meter voltage reads half of what it
read without the potentiometer the remove the test circuit and measere
the potentiometer resistance. Calculate from there.

On 2011-12-06, BeeJ <nospam_at_spamnot.com> wrote:
How about putting a potentiometer in series with the meter +.
Adjust the potentiometer until the meter voltage reads half of what it
read without the potentiometer the remove the test circuit and measere
the potentiometer resistance. Calculate from there.

If you can read the resistance of a potentiometer, you most likely have a
multimeter which, being multi, has modes for measuring voltage and
current.

Just put /that/ in series with the device, and flip it to current
measuring
mode to obtain the current drain directly.

On Mon, 5 Dec 2011 15:48:22 -0800, "Stumpy" <perilmung_at_spamnet.corn
wrote:

I've got an old car that sees sporadic use from a new(learning) driver.
After sitting unused for ~3 weeks it had a low battery, but charged right
up
overnight. I want to leave a 9-15v horizontal panel meter dangling from
the
12v cigarette lighter outlet in order to monitor battery health. Problem
is
that the outlet is unswitched, meter is deflected even when the ignition
is
off.

Can anyone point me to a procedure for measuring or calculating the
current
drain from the meter?

The meter says CK-250A, Taiwan and it is very small made from clear
plastic.
Looks like it was manufactured for inclusion into a 12v battery charger.
I
bought it at an old industrial liquidator outlet - now closed.

TIA


Check the meter with an ohmmeter.

John

On Mon, 5 Dec 2011 15:48:22 -0800, "Stumpy" <perilmung_at_spamnet.corn
wrote:

I've got an old car that sees sporadic use from a new(learning) driver.
After sitting unused for ~3 weeks it had a low battery, but charged right
up
overnight. I want to leave a 9-15v horizontal panel meter dangling from
the
12v cigarette lighter outlet in order to monitor battery health. Problem
is
that the outlet is unswitched, meter is deflected even when the ignition
is
off.

Can anyone point me to a procedure for measuring or calculating the
current
drain from the meter?

The meter says CK-250A, Taiwan and it is very small made from clear
plastic.
Looks like it was manufactured for inclusion into a 12v battery charger.
I
bought it at an old industrial liquidator outlet - now closed.

TIA


Check the meter with an ohmmeter.

John

"Kaz Kylheku" <kaz_at_kylheku.com> wrote in message
news:20111205165432.291_at_kylheku.com...
On 2011-12-06, BeeJ <nospam_at_spamnot.com> wrote:
How about putting a potentiometer in series with the meter +. Adjust
the potentiometer until the meter voltage reads half of what it read
without the potentiometer the remove the test circuit and measere the
potentiometer resistance. Calculate from there.

If you can read the resistance of a potentiometer, you most likely have
a multimeter which, being multi, has modes for measuring voltage and
current.

Just put /that/ in series with the device, and flip it to current
measuring
mode to obtain the current drain directly.

I do have a multimeter but thought maybe that the multimeter itself
would change the circuit. The original meter may be "dynamic" and have
varying resistance as the needle is deflected.

I'll put a multimeter in during daylight hours.

On Mon, 05 Dec 2011 18:01:26 -0800, Stumpy wrote:

"Kaz Kylheku" <kaz_at_kylheku.com> wrote in message
news:20111205165432.291_at_kylheku.com...
On 2011-12-06, BeeJ <nospam_at_spamnot.com> wrote:
How about putting a potentiometer in series with the meter +. Adjust
the potentiometer until the meter voltage reads half of what it read
without the potentiometer the remove the test circuit and measere the
potentiometer resistance. Calculate from there.

If you can read the resistance of a potentiometer, you most likely have
a multimeter which, being multi, has modes for measuring voltage and
current.

Just put /that/ in series with the device, and flip it to current
measuring
mode to obtain the current drain directly.

I do have a multimeter but thought maybe that the multimeter itself
would change the circuit. The original meter may be "dynamic" and have
varying resistance as the needle is deflected.

I'll put a multimeter in during daylight hours.

I don't think that a multimeter so profoundly cheap as to make the
measurement invalid exists.

Is the multimeter a light bulb, with a little card that equates filament
color with current? No? Then it's good enough.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

Oddly, with the black lead of the multimeter on the + terminal of the
original meter(and red on negative terminal) it is 4.4Mohms but with the
leads reversed it is "open" "O.L Mohms".

"Stumpy"

Oddly, with the black lead of the multimeter on the + terminal of the
original meter(and red on negative terminal) it is 4.4Mohms but with the
leads reversed it is "open" "O.L Mohms".

** The meter has a 9.1 volt zener diode inside it - that is how it reads
only from 9 volts and up.

The current draw is gonna be tiny and nothing to be concerned about.



... Phil

"Kaz Kylheku" <kaz_at_kylheku.com> wrote in message
news:20111205165432.291_at_kylheku.com...
On 2011-12-06, BeeJ <nospam_at_spamnot.com> wrote:
How about putting a potentiometer in series with the meter +.
Adjust the potentiometer until the meter voltage reads half of what it
read without the potentiometer the remove the test circuit and measere
the potentiometer resistance. Calculate from there.

If you can read the resistance of a potentiometer, you most likely have a
multimeter which, being multi, has modes for measuring voltage and
current.

Just put /that/ in series with the device, and flip it to current
measuring
mode to obtain the current drain directly.

I do have a multimeter but thought maybe that the multimeter itself would
change the circuit. The original meter may be "dynamic" and have varying
resistance as the needle is deflected.

"Phil Allison"<phil_a_at_tpg.com.au> wrote in message
news:9k5i16FotfU1_at_mid.individual.net...

"Stumpy"

Oddly, with the black lead of the multimeter on the + terminal of the
original meter(and red on negative terminal) it is 4.4Mohms but with the
leads reversed it is "open" "O.L Mohms".

** The meter has a 9.1 volt zener diode inside it - that is how it reads
only from 9 volts and up.

The current draw is gonna be tiny and nothing to be concerned about.



... Phil


Thanks, I agree. The original equipment battery was 80AH so
80AH/.0068A=11,765 hours=490days=13.6years

I'll leave the thing in forever.

On 12/5/2011 10:05 PM, Stumpy wrote:
"Phil Allison"<phil_a_at_tpg.com.au> wrote in message
news:9k5i16FotfU1_at_mid.individual.net...

"Stumpy"

Oddly, with the black lead of the multimeter on the + terminal of the
original meter(and red on negative terminal) it is 4.4Mohms but with
the
leads reversed it is "open" "O.L Mohms".

** The meter has a 9.1 volt zener diode inside it - that is how it
reads
only from 9 volts and up.

The current draw is gonna be tiny and nothing to be concerned about.



... Phil


Thanks, I agree. The original equipment battery was 80AH so
80AH/.0068A=11,765 hours=490days=13.6years

I'll leave the thing in forever.

Now that you have a meter on the battery, how low do expect to let
the voltage get before you start the motor and let it run a while?

Why not just start the car once a week.

Mikek

"amdx" <amdx_at_knologynotthis.net> wrote in message
news:f3f12$4ede0efe$18ec6dd7$19983_at_KNOLOGY.NET...
On 12/5/2011 10:05 PM, Stumpy wrote:
"Phil Allison"<phil_a_at_tpg.com.au> wrote in message
news:9k5i16FotfU1_at_mid.individual.net...

"Stumpy"

Oddly, with the black lead of the multimeter on the + terminal of the
original meter(and red on negative terminal) it is 4.4Mohms but with
the
leads reversed it is "open" "O.L Mohms".

** The meter has a 9.1 volt zener diode inside it - that is how it
reads
only from 9 volts and up.

The current draw is gonna be tiny and nothing to be concerned about.



... Phil


Thanks, I agree. The original equipment battery was 80AH so
80AH/.0068A=11,765 hours=490days=13.6years

I'll leave the thing in forever.

Now that you have a meter on the battery, how low do expect to let
the voltage get before you start the motor and let it run a while?

Why not just start the car once a week.

Mikek



Of course, but technically its not my car. I'm just the responsible adult.