Corrosion. 12.5VDC dont mean sh!t

[posplayr]

It would actually be 12 ohms of resistance. V=IR, 12!=1*1.

QUOTE]

Whoops Yea I got in a hurry ; as you mentioned, still no way the meter impedance is going to affect the measurements.

Funny how different people with all the same "tools" can come up with the exact opposite conclusions.

 

[bonanzadave]

Since I'm being bashed for my field of work/business/equipment:

Not by me. I have nothing but respect for your knowledge. Plus I still need help fixin my TV.

 

[mottyl]

"Plus I still need help fixin my TV"

Bonanzadave,

No promises but I was fairly current with televisions unitll about 3 years ago.

If you want to pm with the make, model and fault I will let you know if I have any thoughts.

Now! Back to the discussion.

Chris

 

[850GT_Rider]

Test equipment

Test equipment

Electric and electronic (yes, Virginia, there IS a difference) test equipment and tools are no different than all our mechanical tools. 40 years in electronics has taught me that none are suitable for every purpose. I've been playing with this stuff since TV's had vacuum tubes, fer chrissakes.

As stated earlier, for the test in question (the lights don't light), a test light is the best tool, or any VOM used to check resistance, not voltage. To check charging systems, a good analog VOM is the best choice. Neither will get fooled by trickle voltages that won't even light a dome light.

Didn't mean to start a p*ssing contest over the whole thing......

 

[bonanzadave]

Not by me. I have nothing but respect for your knowledge. Plus I still need help fixin my TV.

Where did Mr. teddux go ? :-k And all his posts ?

 

[teddux]

Whoops Yea I got in a hurry ; as you mentioned, still no way the meter impedance is going to affect the measurements.

Funny how different people with all the same "tools" can come up with the exact opposite conclusions.

Here is a similar problem on one of my bikes,
Draw your own conclusions:

Battery Voltage (Red & Black)

Analog meter testing battery voltage

Digital Meter testing battery voltage

Key-Switch Voltage Lead (Yellow)

Analog Testing Switch Voltage

Digital Testing Switch Voltage

 

[teddux]

Where did Mr. teddux go ? :-k And all his posts ?

This starts below this post.

Other foolish/"debatable" crap:
"Input Impedance" of Analog

Modified "posplayr impedance"

Value of Added resistor

Adding Resistor to Analog

Modified to "posplayr impedance"

Analog Testing Modified "posplayr impedance"
Key-Switch Voltage

Modified to "posplayr impedance"
Direct battery voltage.

 

[850GT_Rider]

ok...is all that proving you agree with the premise or not?

 

[teddux]

Watch out when checking for voltages with a digital voltmeter. The input impedance is so high that a mere trickle voltage is enough for them to register.
You'll have better luck using one of the 12vdc trouble lights. I've added a really long clip lead to the negative side of mine. Clip it to the -side of the battery to check for 12 volts. Clip it to the + side and you can check for ground continuity. And I still use an analog VOM a lot. Much more dependable than a digital unit sometimes.

Yes, I agree with you 1,000,000%
I also state that an analog is satisfactory for the job.
The point is that the amount of current required to DEFLECT the analog needle is proportionally equivalent to the current required to "light" a bulb.

To move the needle further "full-scale" will require MORE current.

 

[teddux]

Where did Mr. teddux go ? :-k And all his posts ?

Forgot to "take meds", sry.
This is now libel...

 

[duaneage]

Meters used to be rated. A typical rating was 20000 ohms per volt. This meant that the meter offered 20K per every volt read. FET meters came along ( and VTVM before them) with high impedances of around 1M ohms per volt, effectively isolating the whetstone bridge from the circuit under test.

Today even a cheapo meter will have a high enough impedance to not affect a circuit that much.

There are more important things going on than this.

 

[teddux]

Meters used to be rated. A typical rating was 20000 ohms per volt. This meant that the meter offered 20K per every volt read. FET meters came along ( and VTVM before them) with high impedances of around 1M ohms per volt, effectively isolating the whetstone bridge from the circuit under test.

Today even a cheapo meter will have a high enough impedance to not affect a circuit that much.

There are more important things going on than this.

Isn't that wot i said earlier?
Oh, well...deleted.

 

[posplayr]

Yes, I agree with you 1,000,000%
I also state that an analog is satisfactory for the job.
The point is that the amount of current required to DEFLECT the analog needle is proportionally equivalent to the current required to "light" a bulb.

To move the needle further "full-scale" will require MORE current.

OK, I think that several people here including yourself understand the effects of meter input impedance on the measurement. We also understand the difference input impedance between an analog movement 30-40K/volt meter and a FET based (1-10Mohms) input meter.

(for those that dont know, there is a voltage divider setup between the meter and the source impedance which determines whether the meter will be reliable of not for an unloaded test.)

Here is the problem, you are calling a battery tester an "analog meter" as if it is an analog volt meter. That is only partially correct ;it is an analog movement yes, but has a very low input impedance commensurate with the source like that of a battery (only 10's or ohms per volt). Therefore it is very misleading in the current context.

An analog volt meter would have behaved very similarly to a FET meter (essentially +12V at the measurement), while your battery tester would have immediately picked up on the resistance in the bad connector.(at it is doing).

Bottom line, a Battery tester is not an analog volt meter even though the internal schematic (less the resistance values) looks the same.

On the other hand you point out a very nice feature of the battery tester; it will not be fooled like the Volt meters will.:dancing:

 

[teddux]

OK, I think that several people here including yourself understand the effects of meter input impedance on the measurement. We also understand the difference input impedance between an analog movement 30-40K/volt meter and a FET based (1-10Mohms) input meter.

Here is the problem, you are calling a battery tester an "analog meter" as it it is an analog volt meter. That is only partially correct ;it is an analog movement yes, but has a very low input impedance commensurate with the source like that of a battery (only 10's or ohms per volt). Therefore it is very misleading in the current context.

An analog volt meter would have behaved very similarly to a FET meter (essentially +12V at the measurement), while your battery tester would have immediately picked up on the resistance in the bad connector.(at it is doing).

Bottom line, a Battery tester is not an analog volt meter even though the internal schematic (less the resistance values) looks the same.

On the other hand you point out a very nice feature of the battery tester; it will not be fooled like the Volt meters will.:dancing:

I don't understand a word you're trying to say.

 

[Guest]

Another buzz kill
:-#

 

[posplayr]

I don't understand a word you're trying to say.

Sorry, I cant say it any plainer

 

[posplayr]

Another buzz kill
:-#

how was the food?

I was hungry all day Mon after streaching my stomach out Sun nite