PeachParts Mercedes-Benz Forum - View Single Post - ...can I test for a current of two Ohms with this voltmeter?

JamesDean · #11 05-29-2013, 03:11 PM

Quote:

Originally Posted by Air&Road

Jooseppi,

There should be no need to test current draw on an item like that. To measure current you will have to disconnect the circuit and put your meter in series. Determine what current you are looking for, so that you can ensure that you have a meter heavy enough to handle the current. With an analog meter you will also have to be DARN SURE that you get the polarity correct, or you can blow the meter.

A simple way to measure current is to get a high power, .1 Ohm resistor and put it in series with the circuit under test. Then measure the Voltage drop across the resistor and do the Ohms law math to determine the current.

Why are you wanting to measure current draw rather than just ensure that there is voltage to the component or point in the circuit under test?

Not to put words in his mouth, but I recall from another thread he is trying to sell a rear window to someone (maybe funola?) and that someone asked to see how much current the window uses to assess its defroster health.

I replied and told him to measure the resistance of the heater lines connection at the back window and use ohms law to figure out the current usage, which, is most likely 10-15A? I can't remember what its fused to... 200 Watts = ~16 Amps. Are they fused to 25?

I know that MOST meters will not pass that much current...They are typically 10A max (unfused/fused). So if he were to go that path...it could/would likely burn up the leads and/or kill the meter.