Low Amps Probe

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  • 909wheeler
    Junior Member
    • Dec 2015
    • 5

    Low Amps Probe

    Snappy?
    AESwave?
    Pico?

    Saw a thread that showed a good amount of noise on the AESwave LAP. Suggestions?
  • Crusty
    Senior Member
    • Dec 2007
    • 2450

    #2
    Originally posted by 909wheeler
    Snappy?
    AESwave?
    Pico?

    Saw a thread that showed a good amount of noise on the AESwave LAP. Suggestions?
    I have the SnapOn low amps probe. It's pretty good but sometimes it "floats" a bit and once I'm down to measuring anything under 20 or 25 milliamps I can't trust it implicitly but It certainly isn't a POS. It won't zero down below 11-ma in the first place so once I'm down to the lower values I put in a knife switch on the battery and do a direct measurement when I'm chasing a parasitic drain.

    Comment

    • 909wheeler
      Junior Member
      • Dec 2015
      • 5

      #3
      Interesting, had the same results with the Snappy doing parasitic drain testing. Could not zero it out no matter what I tried. So inline testing is what you suggest for parasitic drain testing?

      The one im using is a C version. Do the D versions have better accuracy/zero?

      Comment

      • Witsend
        Banned
        • Nov 2012
        • 2942

        #4
        I would think an inline testing parasitic draw with a $39.99 HF Cent Check meter on milliamp scale still be more accurate than a low amp probe of a scope as long as you don't blow the 2A fuse of the meter and not know it.
        I don't know if it would be worth a damn to try and use it to voltage drop across fuses like someone in the past claims a parasitic draw on a circuit can be pinpointed?
        How would a 35ma parasitic draw have any measurable voltage drop across a 20A fuse unless you substituted a tiny 1 a fuse and the hair sized metal wire temperature starts to rise a degree or two?Sometimes you even have trouble getting a good enough consistent contact using a Power 3 probe testing fuse continuity to power or ground and display KOER voltage dependably

        Comment

        • Crusty
          Senior Member
          • Dec 2007
          • 2450

          #5
          Originally posted by 909wheeler
          Interesting, had the same results with the Snappy doing parasitic drain testing. Could not zero it out no matter what I tried. So inline testing is what you suggest for parasitic drain testing?

          The one im using is a C version. Do the D versions have better accuracy/zero?
          Parasitic drain testing is best done without using "intrusive" methods, at first.
          Because the low amp probes can't be trusted under about 20-ma, once you're down to very low values, THEN switch to direct measuring. Very often simply opening the circuit releases the drain and it won't show up so I always go to extreme measures to ensure the vehicle has an auxiliary battery connected while I install the knife switch.
          If you've got a 200-ma drain the low amps probe will pick it up. Once you're down to lower values direct measuring is best (IMHO)

          I have the "D" model and still can't get it to zero down reliably. Same experience as you have had, but I was told the fact that it wouldn't ZERO and stayed at 11-ma was "negligible" which I wasn't impressed with.
          When we zero a meter, as we should, the meter should go to zero.

          As for the method of measuring the voltage drop across a fuse that Witsend mentions, it works but only with high quality meters, and again, it isn't appropriate for very low current drains such as 5, 10 or 20 milliamps. It's a starting point only, especially when many circuits branch off in several directions.

          Most people are of the opinion that anything under 50-ma is acceptable but that is not appropriate for todays vehicles where they can be as low as 10-ma and 12-ma TOTAL for the vehicle. Some vehicles are around 15 and 20 and 25-ma so when the factory total is that low, the 11-ma that my low amps probe won't zero down below becomes an issue. Sometimes it's PLUS 11-ma and some times it's MINUS 11-ma. That in itself is a 22-ma variance which ruins the tool AFAIC and is anything BUT "negligible"-!!

          If my low amp probe shows 35-ma, is it 24 or 46-?? 24 I would be happy with but 46 could be more than it should be.

          The memory drains of todays vehicles have lowered significantly from what they were in the 1980's, even with many more modules on the vehicles.

          If it shows 75, or 130, or 200-ma or more, there IS a problem (as long as we allow enough time for modules to go to "sleep" and power down). THEN I use direct measuring after the larger drain is found and corrected.

          Comment

          • BMW JEDI
            Senior Member
            • Feb 2012
            • 422

            #6
            Originally posted by 909wheeler
            Snappy?
            AESwave?
            Pico?

            Saw a thread that showed a good amount of noise on the AESwave LAP. Suggestions?
            Snap-on EETA308D provides the best results for me, and I have probes from a wide variety of manufacturers.

            Comment

            • sbreland73
              Senior Member
              • Jan 2009
              • 1076

              #7
              Thanks for sharing your results, that is a VERY nice display of comparison!
              S. Breland

              Comment

              • Crusty
                Senior Member
                • Dec 2007
                • 2450

                #8
                Those are nice comparison charts but they appear to be from around a very low current up to FIVE HUNDRED milliamps.

                Are you able to produce a similar comparrison from ZERO to FIFTY milliamps instead of five hundred???

                Comment

                • 909wheeler
                  Junior Member
                  • Dec 2015
                  • 5

                  #9
                  Originally posted by Witsend
                  I would think an inline testing parasitic draw with a $39.99 HF Cent Check meter on milliamp scale still be more accurate than a low amp probe of a scope as long as you don't blow the 2A fuse of the meter and not know it.
                  I have a Very nice Fluke 88V that I using exactly the method Crusty explained below. Low-Amps probe first. Then under 50 mV, switch to inline testing.

                  Originally posted by Crusty
                  Parasitic drain testing is best done without using "intrusive" methods, at first.
                  Because the low amp probes can't be trusted under about 20-ma, once you're down to very low values, THEN switch to direct measuring. Very often simply opening the circuit releases the drain and it won't show up so I always go to extreme measures to ensure the vehicle has an auxiliary battery connected while I install the knife switch.
                  If you've got a 200-ma drain the low amps probe will pick it up. Once you're down to lower values direct measuring is best (IMHO)

                  I have the "D" model and still can't get it to zero down reliably. Same experience as you have had, but I was told the fact that it wouldn't ZERO and stayed at 11-ma was "negligible" which I wasn't impressed with.
                  When we zero a meter, as we should, the meter should go to zero.

                  As for the method of measuring the voltage drop across a fuse that Witsend mentions, it works but only with high quality meters, and again, it isn't appropriate for very low current drains such as 5, 10 or 20 milliamps. It's a starting point only, especially when many circuits branch off in several directions.

                  Most people are of the opinion that anything under 50-ma is acceptable but that is not appropriate for todays vehicles where they can be as low as 10-ma and 12-ma TOTAL for the vehicle. Some vehicles are around 15 and 20 and 25-ma so when the factory total is that low, the 11-ma that my low amps probe won't zero down below becomes an issue. Sometimes it's PLUS 11-ma and some times it's MINUS 11-ma. That in itself is a 22-ma variance which ruins the tool AFAIC and is anything BUT "negligible"-!!

                  If my low amp probe shows 35-ma, is it 24 or 46-?? 24 I would be happy with but 46 could be more than it should be.

                  The memory drains of todays vehicles have lowered significantly from what they were in the 1980's, even with many more modules on the vehicles.

                  If it shows 75, or 130, or 200-ma or more, there IS a problem (as long as we allow enough time for modules to go to "sleep" and power down). THEN I use direct measuring after the larger drain is found and corrected.
                  Yep, use the same method. Dealing with waking up modules is a pain especially on the newer luxury cars.

                  Originally posted by BMW JEDI
                  Snap-on EETA308D provides the best results for me, and I have probes from a wide variety of manufacturers.

                  That's the comparison I saw. Talked to my Snap On dealer today. $329 is the going price. Guess I'll have to bite the bullet.

                  Comment

                  • Crusty
                    Senior Member
                    • Dec 2007
                    • 2450

                    #10
                    Individual modules having low parasitic drain, many times below 10-ma per module is nothing new. It's been that way since the 1980's in fact.


                    This is a post from James Avery on IATN regarding a RCDLR not staying awake to receive a key fob input.



                    This illustrates where it is important to be able to measure low current drains with NON-intrusive testing. He states that the normal parasitic drain of the RCDLR is only 5 to 10 ma.

                    Were someone to be aware that the RCDLR should normally have a 5 to 10 ma drain, they could measure if the module had the drain (as it should) and verify that it is awake to receive a fob input.

                    Comment

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