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Old 05-17-2007, 11:53 AM
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Checking Amp Draw with a Multimeter...

How could I go about checking the amperage draw with a multimeter?

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Old 05-17-2007, 12:34 PM
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How much amperage draw are you looking to find? I think most multi meters are 2A max.
I your looking to see what it is with the car off just disconnect one of the batt. terminals and touch one probe to the terminal and the other to the batt.

If you do it while running you'll most definitly nuke your meter.. or at least the fuse inside.

Or.. if you can find a big enough resister.. that can handle 50 or so amps you could place that in the circuit, measure the voltage drop and calculate the amprage, but thats kinda complicated..
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Old 05-17-2007, 12:41 PM
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I see i see, im just trying to determine how many running amps a stock 00 dakota would have with headlights running.
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Old 05-17-2007, 05:52 PM
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Doc here,

Unless you have a meter Capable of doing 100 amp readings in a series circuit, DON"T use a DVOM..you'll let all the factory installed smoke out.

NEVER Try to take a reading on a running engine with a DVOM set to amps in series..IF you get past "Start" (And I doubt you will) you' ll blow the meter into the next afterlife..your Starter alone will draw around 650 CCA .. Most meters max out at 10 amps.

Get a SYSTEM LOAD check at auto zombie or local electric shop, with a FULL draw on the system.

Less Accurate, Add up all the fuse values, and use that number as "Worst Case" scenario...All Systems on at once.

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Old 05-27-2007, 06:35 PM
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Get one of the clamp type meters, they are meant to be used for this. I just bought a 100 amp clamp meter from Tooltopia for $137 delivered to the house. It measures to 600 volts ac or dc also. Playing around with it the other day I found that my 5 hp single stage Eaton compressor draws 45 amps at startup then runs at 19 amps while the 3 hp PM66 tablesaw draws 38 amps at startup & runs at 17 amps. I have synthetic oil in the compressor if that makes any difference because it is plated at 22-25 amps, would like to get a reading from someone running dino oil & see what theirs draws. Will come in handy seeing how much load is on each circuit at the breaker box or things like what you are trying to do. They also have 600 & 1000 amp meters but I don't think they measure as low as mine which measures down to 1 milliamp.
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Old 05-28-2007, 02:26 AM
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Doc here,

An INDUCTIVE amprobe is a great tool, and good addition to your tool box IF you plan to do a lot of current checking all the time..

You can also do things like check draws at the main breaker box on your home, or balancing out the legs on a three phase distribution panel, or motor draw on a 3 phase motor starter to keep the heaters from popping or the resets from tripping.

For a ONE time check, auto zombie does it for free..

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Old 05-28-2007, 07:57 AM
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Harbor Freight has a starter draw/ battery load tester for like $50, hook it up in series with the - cable, and start turning stuff on but DO NOT induce a load. it reads to 250 amp. and there commonly on sale for around $30
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