Multimeters, How to check for current draw?

Shane...you are limited to what they will measure (check scale) and they often have a seperate port for large readings (10 to 20 amps on some meters) otherwise you use a clamp or a shunt to measure large current values.

My meter will handle only up to 20 amps, but I also have a tong or clamp meter ac/dc that will measure up to 2000 amps.

If you can indicate how much current you desire to measure and or give us a description of your meter or make and model number and if we can we will google it and be able to help you more.

Shane - see thread 67545 (Solar Panels....) where measuring current was discussed in some detail. As said already, there may be limitations with your meter.

A good way of measuring battery currents is to include a known calibrated resistor in series with the battery. Suitable high current ones of 1/1000 (that's one thousandth) of an ohm are available from Jaycar and elsewhere for $20+. By measuring the voltage drop across such a resistor you can get an accurate measure of the current flowing. With a 1/1000 th ohm resistor each amp results in 1 millivolt.

HTH

John

Can I suggest you have a look at this website. Most informative.

To measure current draw, you really need a 'clamp' meter, not a multi meter.

Until recently DC clamp meters were very expensive, but not so any more.

I bought this clamp meter on E Bay and it has been very good. It is a combined multi meter and clamp meter.

There are lots of others available, but this was about the cheapest and so far, it has done the job. I find it very handy when working on the 12 Volt systems in the vehicle and van.

Norm C

To measure current using a multimeter, you need to "break" into the wiring in which the current is flowing.

You need to use the current-measuring terminals on the multimeter.

BE SURE to move you test leads back to the voltage-measuring terminals when you've finished !! The current-measuring terminals are like a short circuit and will result in BIG sparks if you connect them across a battery to measure its voltage.


Jaycar make a special current-measuring adapter that plugs into a fuse-holder.

Here is the same one with free postage from Hong Kong for 38.67
http://www.dealextreme.com/details.dx/sku.15220

I havent bought from these people yet but will try then soon

Dunedigger