I am wondering how to go about high amp testing? My SO dealer tells me the verdict can do so but he does'nt have a clue as to how! He states that the Verdict is "Hybrid" ready. Mostly I would like to be able to check alternator output and starter draw. I assume I need a high Amp clamp but which one is recommended and how do you set the meter up since it has no hi amps probe selection from the menu? All I have is Low Amps 20 and 40?
High Amp testing
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The high amp probe you purchase will come with a mV conversion and you will set up the scope to mV scale and convert to amps.
Earl -
I am wondering how to go about high amp testing? My SO dealer tells me the verdict can do so but he does'nt have a clue as to how! He states that the Verdict is "Hybrid" ready. Mostly I would like to be able to check alternator output and starter draw. I assume I need a high Amp clamp but which one is recommended and how do you set the meter up since it has no hi amps probe selection from the menu? All I have is Low Amps 20 and 40?
user definable probe settings whereby you can tell the scope how to read a given probe and translate it accurately in the units of measure you choose, such as amps, pressure, vacuum, temperature, etc. In your case you could tell the scope 1mv=1 amp and it would convert the high amps reading for you from then on. The old Interro PDA allowed you to do this.
Having these probes read out onscreen as amps, degrees, psi, in/hg, etc instead of millivolts and then having to convert them would be much handier. It would better help you on saved scope recordings to define what you were looking at, and it would be far less confusion for your customers if you show them wave forms to help explain your diagnosis of their problem.You can expect the reputation of your business to be no better than the cheapest item or service you are willing to sell. - WheelComment
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Amp probes
So I purchased the snap-on high amp probe that's rated from 10-600amps. It has a 40 amp and a 400 amp setting. It says 1mv=1amp. So I tried a starter draw test with it today and was a little confused by the output. I tried a few settings including graphing it and scoping it. Not exactly sure the best way to set up the scope for starter draw but first set it on the lowest scale availiable which was 100mv dc, I ended up changing to 200mv because the pattern was off the screen. What I did not expect to see was -voltage or what I would consider to be a/c voltage? The capture is a brand new starter I installed on a ford taurus.
so my question here is from what I see I assume the starter is drawing roughly 80amps? And do I need to A/C couple to show just the D/C voltage?
Below is a capture of the problem starter, I was surprised to see such a low amp draw since the vehicle would not even start with this starter but I suspect that is because the starter is not actually turning?
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Don't know if this will help at all but I made acouple of videos on using an low amp and a high amp probe for relative compression and starter testing http://www.youtube.com/watch?v=zKvxG...eature=channel not the greatest videos but others will appear in the side bar if you hit the link. There is also a thread on this in the lab scope forum.Comment
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A few things to try
So I purchased the snap-on high amp probe that's rated from 10-600amps. It has a 40 amp and a 400 amp setting. It says 1mv=1amp. So I tried a starter draw test with it today and was a little confused by the output. I tried a few settings including graphing it and scoping it. Not exactly sure the best way to set up the scope for starter draw but first set it on the lowest scale availiable which was 100mv dc, I ended up changing to 200mv because the pattern was off the screen. What I did not expect to see was -voltage or what I would consider to be a/c voltage? The capture is a brand new starter I installed on a ford taurus.
so my question here is from what I see I assume the starter is drawing roughly 80amps? And do I need to A/C couple to show just the D/C voltage?
Below is a capture of the problem starter, I was surprised to see such a low amp draw since the vehicle would not even start with this starter but I suspect that is because the starter is not actually turning?
Hi cbender,
Although the VERUS/MODIS or Vantage Pro are only sold with a 0-40 or a
0-60 amp probe as an option to them and the low amp probes have been designed specifically to work for them, you can use a high current probe. With the low current amp probes the current is calculated for you, but with the high current probes it will take a little bit more work to setup. And you must convert the voltage to the amps as per documentation that comes with the probe. Looking at the waveform it looks like a faster time base of maybe 2 seconds might allow you to view the waveform better.
Also you might want to verify that you have a good battery with a good voltage supply, try running a voltage drop test if the starter is not turning (both power and ground side). It is possible there may be a high resistance in the circuit which would account for low amperage. (The amperage draw shown may only be from the starter solenoid).
Hope this helps, Dynodave
Last edited by Dynodave; 03-20-2011, 11:51 PM.Comment
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cbender,
the waveform is inverted. amp probes are directional. turn yours around and show us what you find.Comment
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Here is a video showing just the high amp probe checking starter draw and alternator output and scope set up. Hope this helps http://www.youtube.com/watch?v=63LWyxP7CnYComment
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