Clamp style amp meters

[mike killay]

Has anyone used a clamp style amp meter to measure amps on their bike?
The reason I ask is that besides wishing to measure the bike, I also have an electric outboard motor.

 

[neptune]

As I understand it, the common type of clamp meter will only measure AC amps. Furthermore, you must have only one conductor passing through the clamp. So it would depend on what exactly you want to measure, and why. The nearest thing you would get to AC on a bike is in the phase wires of a brushless motor, and that would be square wave, or pulsed DC. This would give an inaccurate reading, and would only measure the current to one phase of the motor. The solution will depend on whether you need to permanently monitor current, or just a one-off test. There are cheap moving coil ammeters available, but you have the hassle of wiring them in .

 

[oigoi]

I have used this one:

AC/DC Voltage & Current Clamp Meter - Tecpel DCM-033 - Digital-Meters.com

It works well. You have to measure a single cable, it cannot measure a multicore cable as it measures the current using the magnetic field generated by the current flowing through the cable.

This type of meter is not good for measuring below 0.5 amps in my opinion. I have done some back to back tests with a normal ammeter and measuring a few amps (up to 10) it was accurate in it's readings

 

[mike killay]

Thanks Ogoi,
No good for my bike because of the need to separate the cables, but ideal for my boat.

Mike

 

[neptune]

@oigoi. You have obviously had more experience of this than me.It is important to define multicore cable . It would not work on a cable having multiple conductors [wires] insulated from one another, but will work on a single conductor made up of multiple strands of wire all of which are then enclosed in insulation.

 

[flecc]

On higher currents DC they read much lower than actual current, as Neptune says, they are designed to measure AC current. For example, mine over the battery lead on one of my cars with battery very low, engine running and charging, the reading is only about a fifth of actual current, an indicator of charging rather than a measure.

 

[vhfman]

DC Clamp meters use a hall effect sensors mounted in a gap in a ferrite ring to measure static magnetic fields. The magnetic field strength is proportional to the current in the wire in the clamp. They work reasonably well with high currents, but when the current in the wire gets very small it becomes more difficult to measure the voltage in the hall effect sensor. Basically the hall voltage becomes buried in noise and accuracy becomes poor.

Here is an example of an adapter for a DMM showing the schematic.

Chris