# converting probles to clamp-on

S

#### *selah*

Jan 1, 1970
0
Is there some adapter device that can convert from plug-in probes to
clamp-on? (like for an ammeter).

Thanks.

M

#### mike

Jan 1, 1970
0
*selah* said:
Is there some adapter device that can convert from plug-in probes to
clamp-on? (like for an ammeter).

Thanks.

Yes, you're welcome.
A more specific question might elicit a more specific answer.
mike

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T

#### Tristar500

Jan 1, 1970
0
check out item number CAT# MTC-21 at the allelectronics.com website.

set of 2 for $3.00. Going to order a couple myself. Lawrence C #### Chris Jan 1, 1970 0 *selah* said: Is there some adapter device that can convert from plug-in probes to clamp-on? (like for an ammeter). Thanks. Hi, Selah. Unless you're waiting for someone to write a novel to cover every possible answer, you might want to be a little more specific: * Do you already have an existing meter you want to use? If so, which one? * Are you interested in measuring DC current, AC current, or both? * If AC, what are the frequencies of interest? Is it a sine wave or other waveform? * What kind of accuracy do you need in this measurement? If you're just interested in a clamp-on ammeter for measuring AC with limited accuracy, you can get cheapie DMMs with a clamp built in for measuring AC curent at line frequencies for less than$20 USD. They're
available at Harbor Freight and other sources. This might be less

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42397

If this doesn't do the job, looking forward to getting more
information.

Good luck
Chris

S

#### *selah*

Jan 1, 1970
0
Chris said:
Hi, Selah. Unless you're waiting for someone to write a novel to cover
every possible answer, you might want to be a little more specific:

* Do you already have an existing meter you want to use? If so, which
one?

It's a micronta digital.
* Are you interested in measuring DC current, AC current, or both?

dc - for now.
* If AC, what are the frequencies of interest? Is it a sine wave or
other waveform?

* What kind of accuracy do you need in this measurement?

..05 mA - the meter has a dc mA setting and setting for 2 mA. I want to
use it to see if the current drain in our car is within range.

S

#### *selah*

Jan 1, 1970
0
Oops - sorry. I just realized - the manual calls for .05A sensitivity -
not mA - so I can't use this meter. Got it confused because the test can
also be done with a shunt and a meter that has .05 mV sensitivity.

Thanks for the responses anyway.

M

#### mike

Jan 1, 1970
0
*selah* said:
It's a micronta digital.

dc - for now.

.05 mA - the meter has a dc mA setting and setting for 2 mA. I want to
use it to see if the current drain in our car is within range.

This is going from bad to worse.
You've got people willing to help, but you're not very forthcoming.
Your numbers are inconsistent with the words. Very few things in a car
can be measured with a 2mA meter. Assuming we have the same notion of
what constitutes a "car".

What the heck are you trying to measure...EXACTLY.
And just for fun, what are you gonna do if you don't like the number?
mike

--
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..
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E

#### ehsjr

Jan 1, 1970
0
*selah* said:
Oops - sorry. I just realized - the manual calls for .05A sensitivity -
not mA - so I can't use this meter. Got it confused because the test can
also be done with a shunt and a meter that has .05 mV sensitivity.

Thanks for the responses anyway.

You more than likely can use the meter.
..05 A = 50 mA and it is likely that your meter has a
range that will accomodate that. On your next post,
tell us the model number of the Micronta meter, and
what the current measuring ranges are. Also, as other
posters have indicated, the information you provide
is incomplete, making it next to impossible to give
you a good answer. For example, you say "the manual
calls for .05A sensitivity". What manual? What is
the manual telling you to do? Why are you doing it -
what problem are you trying to solve or what information
are you trying to gather? etc.

Ed

S

#### *selah*

Jan 1, 1970
0
ehsjr said:
You more than likely can use the meter.
.05 A = 50 mA and it is likely that your meter has a
range that will accomodate that. On your next post,
tell us the model number of the Micronta meter,

The model # is 22-191

and
what the current measuring ranges are.

The current drain is supposed to be less than .05A.

Also, as other
posters have indicated, the information you provide
is incomplete, making it next to impossible to give
you a good answer. For example, you say "the manual
calls for .05A sensitivity". What manual?

Ford shop manual.

What is
the manual telling you to do?

Battery Drain Test with a Clamp-On DC Ammeter

Test Procedure

1. Turn the ignition to OFF and make sure there are no electrical loads.
After determining that the underhood lamp is shutting off properly,
disconnect the bulb.

2. Clamp the meter clip securely around the positive or ground battery
cable (all cables if two or more leads to the post).

NOTE:
Do not start vehicle with clip on cable.

Test Conclusion

The current reading (current drain) should be less than .05 amps.

Why are you doing it -
what problem are you trying to solve or what information
are you trying to gather? etc.

Our battery went dead recently although we just bought it new. We
recharged it. The charger showed that it was at very low charge at the
beginning (the charger ammeter was showing 10A going to the battery),
after about 6 hours it was fully charged and the charger ammeter showed
4A going to the battery. I tested the battery with a hydrometer and the
hydrometer practically didn't float, (it read at the top of the tube in
the dead battery region.) We took the battery in to a repair shop and
they tested it with their "snap-on" tester. I assume it was a load test.
It said the battery was good. These are the results:

Battery size 660 CCA
Available Amp 798 CCA
% Rated Capactiy 120%
Battery Temp 70 F
Initial Volts 12.90 V
Final Volts 12.33 V
Impedance 4.00 m ohms

They also tested the alternator (good) and starter (good).

M

#### mike

Jan 1, 1970
0
*selah* said:
sensitivity -

The model # is 22-191

and

The current drain is supposed to be less than .05A.

Also, as other

Ford shop manual.

What is

Battery Drain Test with a Clamp-On DC Ammeter

Test Procedure

1. Turn the ignition to OFF and make sure there are no electrical loads.
After determining that the underhood lamp is shutting off properly,
disconnect the bulb.

2. Clamp the meter clip securely around the positive or ground battery
cable (all cables if two or more leads to the post).

NOTE:
Do not start vehicle with clip on cable.

Test Conclusion

The current reading (current drain) should be less than .05 amps.

Why are you doing it -

Our battery went dead recently although we just bought it new. We
recharged it. The charger showed that it was at very low charge at the
beginning (the charger ammeter was showing 10A going to the battery),
after about 6 hours it was fully charged and the charger ammeter showed
4A going to the battery. I tested the battery with a hydrometer and the
hydrometer practically didn't float,

This is odd. Your hydrometer says it's dead, but the shop says it's
good. Sounds like a hydrometer problem.

(it read at the top of the tube in
the dead battery region.) We took the battery in to a repair shop and
they tested it with their "snap-on" tester. I assume it was a load test.
It said the battery was good. These are the results:

Battery size 660 CCA
Available Amp 798 CCA
% Rated Capactiy 120%
Battery Temp 70 F
Initial Volts 12.90 V
Final Volts 12.33 V
Impedance 4.00 m ohms

They also tested the alternator (good) and starter (good).

You don't say how old your car is. I have no experience with all the
new electronical stuff in cars. I'd think it would be safe to (somebody
correct me if I'm wrong) take a 1 ohm 1/4W resistor in series between
the battery and the positive wire. If the resistor explodes, you've got
too much current drain. Shouldn't get warm at all. Measure the voltage
across the resistor. 50mV = 50mA. Don't turn on any lights or anything
while you do this cause you will explode the resistor.

Probes capable of measuring 50mA DC with holes that will fit around the
size wire you're measuring are hard to find. And they ain't cheap.
I've got a FW Bell CG100 DC current probe that I was gonna take to a
swap meet next week and try to get \$50 for if you're interested. Only
reason it's anywhere near that cheap is that someone took it apart. I
had to reassemble it and make new labels. Appearance is everything with
resale value.

mike

--
Return address is VALID but some sites block emails
..
Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
Wanted 12" LCD for Compaq Armada 7770MT.
Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
ht<removethis>tp://www.geocities.com/SiliconValley/Monitor/4710/

C

#### Chris

Jan 1, 1970
0
*selah* said:
The model # is 22-191

and

The current drain is supposed to be less than .05A.

Also, as other

Ford shop manual.

What is

Battery Drain Test with a Clamp-On DC Ammeter

Test Procedure

1. Turn the ignition to OFF and make sure there are no electrical loads.
After determining that the underhood lamp is shutting off properly,
disconnect the bulb.

2. Clamp the meter clip securely around the positive or ground battery
cable (all cables if two or more leads to the post).

NOTE:
Do not start vehicle with clip on cable.

Test Conclusion

The current reading (current drain) should be less than .05 amps.

Why are you doing it -

Our battery went dead recently although we just bought it new. We
recharged it. The charger showed that it was at very low charge at the
beginning (the charger ammeter was showing 10A going to the battery),
after about 6 hours it was fully charged and the charger ammeter showed
4A going to the battery. I tested the battery with a hydrometer and the
hydrometer practically didn't float, (it read at the top of the tube in
the dead battery region.) We took the battery in to a repair shop and
they tested it with their "snap-on" tester. I assume it was a load test.
It said the battery was good. These are the results:

Battery size 660 CCA
Available Amp 798 CCA
% Rated Capactiy 120%
Battery Temp 70 F
Initial Volts 12.90 V
Final Volts 12.33 V
Impedance 4.00 m ohms

They also tested the alternator (good) and starter (good).

Hi, Selah. As is frequently the case, the shop manual for the car is
assuming you have tens of thousands of dollars in factory-approved,
factory-supplied equipment. Given that armamentorium, their bean
counters have determined the least expensive, least labor-intensive
method of making the measurement.

I've had your problem before -- an infuriating slow leak of unknown
origin that drains the battery over a day or two. Here's the simple
low tech way to approach the problem:

Before starting this, put a cover over the positive battery terminal
and clamp to prevent accidentally shorting it out. And use goggles
while doing this.

Now, with the key in the OFF position and all accessories turned off,
place your DMM on DC current. Then use alligator clips to connect the
leads of the DMM to the negative terminal of the battery and the
negative battery clamp. Carefully loosen the nut for the negative
clamp, and then carefully remove the clamp from the terminal. At that
point, the circuit and leakage current should be from the POS terminal,
through the car, then through the DMM ammeter to the NEG terminal. You
can then measure the current (which should be less than 0.05A, or 50mA,

You may have to just use the test probe instead of an alligator clip,
if you don't have a dual terminal battery. In that case, just hold the
probe right on the negative terminal as you carefully twist off the
negative terminal clamp.

For newer cars, it can be a big pain to reset and reprogram stuff if
the battery is removed from the car electrical system. However, the
added series resistance of the DMM on DC current shouldn't cause enough
voltage drop to make the computers reset, as long as it's less than a
couple of amps. Avoid even momentarily opening the circuit here, or
you might have a lot more problems.

When this happened to me, I did the above and found about 1/4A of
"leakage" current when everything was supposed to be off. Of course,
it took over an hour to finally track down that a small normally closed
switch for a little convenience bulb in one of the convenience
compartments was jammed in the ON position, even with the convenience
compartment door closed. How inconvenient.

You also always have the option of buying a Hall Effect meter clamp,
which should set you back quite a few bucks. This clamp uses a hall
effect sensor to sense the magnetic field produced by the current
flowing through the wire, and outputs a DC and/or AC voltage
proportional to that current. Several manufacturers make them, they're
all probably too expensive for what you want.

I hope this is of help. If you're not familiar with car electrical
work, you should let someone qualified handle this. And again, don't
forget to cover the positive terminal of the battery to avoid shorting
it out if you do handle it yourself. Worst case, you could enjoy a
sulphuric acid face wash if you're not careful.

Good luck
Chris

P

Jan 1, 1970
0
*selah* said:
sensitivity -

The model # is 22-191

and

The current drain is supposed to be less than .05A.

Also, as other

Ford shop manual.

What is

Battery Drain Test with a Clamp-On DC Ammeter

Test Procedure

1. Turn the ignition to OFF and make sure there are no electrical loads.
After determining that the underhood lamp is shutting off properly,
disconnect the bulb.

2. Clamp the meter clip securely around the positive or ground battery
cable (all cables if two or more leads to the post).

NOTE:
Do not start vehicle with clip on cable.

Test Conclusion

The current reading (current drain) should be less than .05 amps.

Why are you doing it -

Our battery went dead recently although we just bought it new. We
recharged it. The charger showed that it was at very low charge at the
beginning (the charger ammeter was showing 10A going to the battery),
after about 6 hours it was fully charged and the charger ammeter showed
4A going to the battery.

Yes, sounds flat.

I tested the battery with a hydrometer and the
hydrometer practically didn't float, (it read at the top of the tube in

A assume this was before the charging session.
We took the battery in to a repair shop and
they tested it with their "snap-on" tester. I assume it was a load test.
It said the battery was good. These are the results:

Battery size 660 CCA
Available Amp 798 CCA
% Rated Capactiy 120%
Battery Temp 70 F
Initial Volts 12.90 V
Final Volts 12.33 V
Impedance 4.00 m ohms

They also tested the alternator (good) and starter (good).

Hi Ed,

so you want to check whether the car is draining the battery when it's idle?

Have you had any electrical work done prior to your problems like a
towbar fitting, new radio, new alarm system, new alternator? If so,
they would be my prime suspects. Look at the car at night for bulbs
left on (eg interior light, boot light).

I'd try something very simple rather than risking wrecking the meter.

With engine stopped, remove the the *** earth connection *** from your
battery. Note if you get a spark if you re-touch them - an indication

Get a 12 volt bulb, and connect the bulb between battery post and the
lead you've just removed. Do it by hand - no clips, clamps etc; there
will be no flashes or bangs if you fumble bulb, lead, post, chassis
together, provided you stay away from the other post and lead. If a
headlamp bulb shines like a searchlight you have a real problem - load
of five or six amps. Can you get hold of one of those 12v to 24v test
screwdriver things with a bulb in the handle and a trailing lead? Cost
a few pounds in UK, but test it first by connecting between + and - of
the battery and don't ever use it for mains testing! Try that for a
more sensitive test - a mere little tiny glow will be a lot less than
0.05A = 50mA. If you really want to try the meter to actually measure
the drain, then do the bulb test first and only use the meter if you get
a small glow or nothing - try the meter with high current settings
first. Again, just hold the meter leads against the battery post and

If you do get a bulb glowing, then the next step is to find out where
the current is leaking, and pulling fuses might give a clue. Take your
bulb off, pull a bank of fuses, (remember where they came from!) try the
bulb again til you lose the drain. Things like alarm systems, central
locking, radios with reset codes and clocks do draw a small current,
probably far less than the 50mA mentioned.

If having pulled all fuses you still have the drain, remember that some
circuits might not have a fuse - eg generator, starter via solenoid,
horn, but your manual will tell you that. Check by disconnecting them.
A bust diode in the alternator could cause a leak (but might cause
the ignition warning light to glow?).

A warning - I was present when a contractor in a telephone exchange
managed to short an accumulator with a spanner. A nasty big instant
bang with acid and glass all over the place. Wrap tape round the
spanner if you work with the positive (non earthed) lead OR disconnect
the earthed one first.

Good luck ! Let us all know how you get on.

Phil

E

#### ehsjr

Jan 1, 1970
0
Yes, sounds flat.

I tested the battery with a hydrometer and the

A assume this was before the charging session.

Hi Ed,

so you want to check whether the car is draining the battery when it's
idle?

Have you had any electrical work done prior to your problems like a
towbar fitting, new radio, new alarm system, new alternator? If so,
they would be my prime suspects. Look at the car at night for bulbs
left on (eg interior light, boot light).

I'd try something very simple rather than risking wrecking the meter.

With engine stopped, remove the the *** earth connection *** from your
battery. Note if you get a spark if you re-touch them - an indication

Get a 12 volt bulb, and connect the bulb between battery post and the
lead you've just removed. Do it by hand - no clips, clamps etc; there
will be no flashes or bangs if you fumble bulb, lead, post, chassis
together, provided you stay away from the other post and lead. If a
headlamp bulb shines like a searchlight you have a real problem - load
of five or six amps. Can you get hold of one of those 12v to 24v test
screwdriver things with a bulb in the handle and a trailing lead? Cost
a few pounds in UK, but test it first by connecting between + and - of
the battery and don't ever use it for mains testing! Try that for a
more sensitive test - a mere little tiny glow will be a lot less than
0.05A = 50mA. If you really want to try the meter to actually measure
the drain, then do the bulb test first and only use the meter if you get
a small glow or nothing - try the meter with high current settings
first. Again, just hold the meter leads against the battery post and

If you do get a bulb glowing, then the next step is to find out where
the current is leaking, and pulling fuses might give a clue. Take your
bulb off, pull a bank of fuses, (remember where they came from!) try the
bulb again til you lose the drain. Things like alarm systems, central
locking, radios with reset codes and clocks do draw a small current,
probably far less than the 50mA mentioned.

If having pulled all fuses you still have the drain, remember that some
circuits might not have a fuse - eg generator, starter via solenoid,
horn, but your manual will tell you that. Check by disconnecting them.
A bust diode in the alternator could cause a leak (but might cause the
ignition warning light to glow?).

A warning - I was present when a contractor in a telephone exchange
managed to short an accumulator with a spanner. A nasty big instant
bang with acid and glass all over the place. Wrap tape round the
spanner if you work with the positive (non earthed) lead OR disconnect
the earthed one first.

Good luck ! Let us all know how you get on.

Phil
Hi Phil,

the question. That said, your bulb idea is the best, as I see
it. I don't think Selah fully understands how to use his meter,
and if he tries, he may end up harming it.

Ed

P

Jan 1, 1970
0
ehsjr said:
Hi Phil,

the question. That said, your bulb idea is the best, as I see
it. I don't think Selah fully understands how to use his meter,
and if he tries, he may end up harming it.

Ed

Sorry Ed. Yes, I agree about wrecking his meter. I still think it will
be worth his while looking for a courtesy light permanently on first
though! I await the final story.

Phil

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[email protected]

R

#### Rich Grise

Jan 1, 1970
0
Is there some adapter device that can convert from plug-in probes to
clamp-on? (like for an ammeter).

Yes, it's called an "alligator clip."

Cheers!
Rich

S

#### *selah*

Jan 1, 1970
0
Chris said:
Hi, Selah. As is frequently the case, the shop manual for the car is
assuming you have tens of thousands of dollars in factory-approved,
factory-supplied equipment. Given that armamentorium, their bean
counters have determined the least expensive, least labor-intensive
method of making the measurement.

I've had your problem before -- an infuriating slow leak of unknown
origin that drains the battery over a day or two. Here's the simple
low tech way to approach the problem:

Before starting this, put a cover over the positive battery terminal
and clamp to prevent accidentally shorting it out. And use goggles
while doing this.

Now, with the key in the OFF position and all accessories turned off,
place your DMM on DC current. Then use alligator clips to connect the
leads of the DMM to the negative terminal of the battery and the
negative battery clamp. Carefully loosen the nut for the negative
clamp, and then carefully remove the clamp from the terminal. At that
point, the circuit and leakage current should be from the POS terminal,
through the car, then through the DMM ammeter to the NEG terminal. You
can then measure the current (which should be less than 0.05A, or 50mA,

You may have to just use the test probe instead of an alligator clip,
if you don't have a dual terminal battery. In that case, just hold the
probe right on the negative terminal as you carefully twist off the
negative terminal clamp.

For newer cars, it can be a big pain to reset and reprogram stuff if
the battery is removed from the car electrical system. However, the
added series resistance of the DMM on DC current shouldn't cause enough
voltage drop to make the computers reset, as long as it's less than a
couple of amps. Avoid even momentarily opening the circuit here, or
you might have a lot more problems.

When this happened to me, I did the above and found about 1/4A of
"leakage" current when everything was supposed to be off. Of course,
it took over an hour to finally track down that a small normally closed
switch for a little convenience bulb in one of the convenience
compartments was jammed in the ON position, even with the convenience
compartment door closed. How inconvenient.

You also always have the option of buying a Hall Effect meter clamp,
which should set you back quite a few bucks. This clamp uses a hall
effect sensor to sense the magnetic field produced by the current
flowing through the wire, and outputs a DC and/or AC voltage
proportional to that current. Several manufacturers make them, they're
all probably too expensive for what you want.

I hope this is of help. If you're not familiar with car electrical
work, you should let someone qualified handle this. And again, don't
forget to cover the positive terminal of the battery to avoid shorting
it out if you do handle it yourself. Worst case, you could enjoy a
sulphuric acid face wash if you're not careful.

Good luck
Chris

Hello Chris,

I tried using the probes on the + terminal and the reading was 33 mA.
Seems maybe the problem was due to a severely corroded wire on the
starter motor.

Thanks for the help.

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