CDT quiescent drain measurement with clamp meter

[MSS]

Originally Posted by grivas

Hi, I purchased one of these clamps today, as a result of out conversations, I noticed when I opened the pack there was a ball bearing in the black ripper bag, any idea what it is does it have any use?

Some meters do use a small ball bearing as part of the detent mechanism for the range selection rotary switches. I don't know if this particular instrument does but UNI-T make a whole range of meters so one of them probably does. I suspect one has been dropped in the case inadvertently.

I am not aware of any other reason.

[grivas]

Originally Posted by MSS

Some meters do use a small ball bearing as part of the detent mechanism for the range selection rotary switches. I don't know if this particular instrument does but UNI-T make a whole range of meters so one of them probably does. I suspect one has been dropped in the case inadvertently.

I am not aware of any other reason.

Thank you for the explanation, although I am not certain what a 'detent mechanism' is.

By way of information, I had a reply from the manufacturer, their message simply said 'this is useless, simply for testing'.

So curiously, he says, how is a ball bearing used for testing, the meter i suppose?.

[MSS]

This is purely a guess. It could be that they pick up a ball bearing between the clamp ends - if it does not fall out, the springs in the clamp are applying sufficient compression to the clamp to ensure good closing action.

But, as I say, it is a pure guess.

[polinsteve]

Originally Posted by Mike Noc

If only it was that simple Steve. Problem is you want to measure the parasitic drain in milliamps but the system can generate a few amps before shutting down and if your cheap meter is in series with the circuit and switched to milliamps then you've blown a fuse at least....and if you wait until everything is shut down and then switch the meter from a higher reading to milliamps you risk waking the ECUs up due to the break in the circuit as you switch over.

Easily got round using a second battery as suggested by French Mike, and I think Harry on here had another way round it.

I agree with you - I just use an inline meter. Not a cheap one though!

I should have said. any open doors, clamp the switch and the same on the bonnet. With care, after the systems have gone to sleep, insert the meter into the circuit without breaking the circuit. However, your spare battery idea sounds easier.

[Mike Noc]

I can't take the credit for the idea, it came from French Mike.

[Ducati750cc]

Just a quick thanks to MSS for bringing my attention to the UNI-T.


I have used my old faithful LEM HEME LH1010 AC/DC ( a big beast in comparison to the UNI ), same as the old Fluke 1010, clamp meter for about 20 years, still going strong after being knocked from pillar to post many times.


I'm not too bothered if the clamps are not 100% accurate, if I need 100% accuracy I'll do it in line.


So, I spent some money and a few hours yesterday playing with my new toy and was very pleasantly pleased with the compact size, lightness, functions and uncomplicated function selection process.


The push button zero function is a godsend after spending a lifetime zeroing the LEM with the exceptional sensitive zero knob, having to hold my breath and having to handle it gently as if it was a bottle of Nitroglycerin.


The auto-ranging and range of readings is good.


My only gripe and it is a very, very, tiny one is the leads, I've swapped them over for some spare silicone multi tipped ones I had knocking about to improve accuracy and versatility, but for 99.9999% percent of the time and for most folk they will do the job perfectly.


Thanks again, amazing how time and technology moves on, yet in many cases we, me included, only replace many things when they break and not because there is a better tool.


Just took the battery out of the LEM and put it in the ' spare in case the new tool fails ' cabinet, but they never do.