A clamp on ammeter only works on alternating current using magnetic induction so it would not show any current flow for the direct current used in automobiles.
So how do I use this?
Hey, so I bought an AC clamp meter with the intent of checking how much draw there was on my car battery while the engine was off / car was supposedly sleeping.
I turned it to the "A~" position and clamped it round the negative battery cable - it read 0. So I guess I'm doing something wrong?
View attachment 25075
Any clever people here know what I'm supposed to do with it? I know I should probably RTFM too... ><
Cheers
Alex
I turned it to the "A~" position and clamped it round the negative battery cable - it read 0. So I guess I'm doing something wrong?
View attachment 25075
Any clever people here know what I'm supposed to do with it? I know I should probably RTFM too... ><
Cheers
Alex
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That might be why. You can all stop laughing now 
Some have the ability to read AC and DC. See here
You put it round the live cable to see what amperage is being drawn
Roger.
You put it round the live cable to see what amperage is being drawn
Roger.
Cheers Roger, just ordered one that supports AC and DC...
Incorrect info, go to the bottom of the class.:wink:A clamp on ammeter only works on alternating current using magnetic induction so it would not show any current flow for the direct current used in automobiles.
OK, so I should have said THAT clamp on ammeter cannot measure direct current.
Are you sure your clamp on ammeter.is capable of reading such a low amperage? MILLIAMPS
You'll not get a DC clamp meter with resolution less than 100ma amps to my knowledge , my Flir one is 0.1a for sure.Hey, so I bought an AC clamp meter with the intent of checking how much draw there was on my car battery while the engine was off / car was supposedly sleeping.
I turned it to the "A~" position and clamped it round the negative battery cable - it read 0. So I guess I'm doing something wrong?
View attachment 25075
Any clever people here know what I'm supposed to do with it? I know I should probably RTFM too... ><
Cheers
Alex
Best checked with a Fluke DMM in series on 10amp range , then switch to 400ma range once all interior lights off etc.
I bought a Tacklife CM01A (AC/DC clamp meter) - I set it to 40A, and to DC - it shows 1.16a when clamped to the battery positive cable. The car had been locked all night and I only opened the boot to get at the battery (i.e. didn't fully unlock the car)
Not sure if that's a good or bad reading for the cars state.... I plan to test different scenarios later i.e. fully unlocked, just after it's been driven etc. Kind of interested to see how the drain changes when things go to 'sleep' in the car.
Cheers,
Alex
Not sure if that's a good or bad reading for the cars state.... I plan to test different scenarios later i.e. fully unlocked, just after it's been driven etc. Kind of interested to see how the drain changes when things go to 'sleep' in the car.
Cheers,
Alex
If you use a screw driver to trip the lock in the open tailgate, it will think that the boot is shut again and you can get a sleeping reading.
Just press the unlock button on the fob to release the latch before you close the tailgate again otherwise the latch will hit the striker.
Just press the unlock button on the fob to release the latch before you close the tailgate again otherwise the latch will hit the striker.
so - a couple of things here....
when you open the boot, then the car will go into a sort of alert mode, where things are "woken up". I would quite rightly expect some discharge there.
for a better test, wait long enough with the boot open until the car has nodded off again, probably after the courtesy lamp has gone out and then measure
......and of course, a current draw large enough to drain the battery over a couple of days would be small enough to be very difficult to detect with a current clamp. At those small currents, and old-fashioned multimeter would be better
when you open the boot, then the car will go into a sort of alert mode, where things are "woken up". I would quite rightly expect some discharge there.
for a better test, wait long enough with the boot open until the car has nodded off again, probably after the courtesy lamp has gone out and then measure
......and of course, a current draw large enough to drain the battery over a couple of days would be small enough to be very difficult to detect with a current clamp. At those small currents, and old-fashioned multimeter would be better
As above, unlocking the car puts it back into convenience mode; stuff like the seating column motors/memory, seat adjustment, mirror adjustment become active and the satnav/infotainment system and climate control go into a half-started standby state. If you want to get a true reading with the car locked then leave the battery cover out and remove the loadspace cover in the tailgate, it just unclips, that should leave the clamp meter visible through the rear window without having to open the car.
By the time that the car has gone to sleep , the clamp meter will have gone to sleep too / powered off ......As above, unlocking the car puts it back into convenience mode; stuff like the seating column motors/memory, seat adjustment, mirror adjustment become active and the satnav/infotainment system and climate control go into a half-started standby state. If you want to get a true reading with the car locked then leave the battery cover out and remove the loadspace cover in the tailgate, it just unclips, that should leave the clamp meter visible through the rear window without having to open the car.
You will need to remove the negative lead , put in a couple of meters cable extension ( small wire )
Leave this out of the boot shut to give you something to clamp , should be around 50mA / 0.05 amps,
As per my previous post , you may only see 0.1 amps / 100mA minimum due to resolution,
Would be better measured with a DMM on a lower current DC range , 500mA or less.
I didn't realise the meter would go to sleep, fair point. In that case, are you not as well to just use a multimeter with croc clip leads and run those out of the boot?
Just to be clear, I am only talking about unlocking the boot here with the fob, not the whole car.As above, unlocking the car puts it back into convenience mode
I can't vouch for other model years but on my '07 if you lock the car but leave a window open then wait for it to drop out of convenience mode before opening the boot the air con aspirator doesn't start spinning, you can't move the seats, the touch screen doesn't come on, the nav unit doesn't start spinning etc, etc, etc so the car doesn't go in to convenience mode.
As soon as you shut the boot the indicator lights flash to acknowledge that the alarm is back on. Tripping the lock mechanism with a screw driver has the same effect and obviously also switches off the lights in the boot.
The workshop manual says:
Convenience Mode
When a door is opened, for a vehicle with either remote RF central locking or passive entry, the vehicle's electrical system
initiates the convenience mode. The following systems become active...
and for the tailgate release:
Liftgate Release
A liftgate release button can be pressed to open the liftgate. This will operate with car locked and alarmed or unlocked. If
the vehicle is locked and alarmed, when the liftgate release button is pressed, the liftgate can be opened without
triggering the alarm system. When the liftgate is subsequently closed, the alarm will be re-activated.
I think for that, "door" will also include tailgate
Don't presume, just go and try it on your car as well and you will find that I am right unless my car is unique!I think for that, "door" will also include tailgate
Hey guys, thanks for all the replies - below are my test results
Car locked - 0.4a
Car locked (10 minutes later) 0.03a
Boot (trunk) door only unlocked - 1.4a
Car globally unlocked - 9.10a
I did hit the issue with the clamp meter going to sleep so basically had to stand there and watch it - I’m sure the neighbours think I’m mad.
My experiment was basically to ensure there wasn’t excessive drain on the battery while it was supposed to be sleeping - now I do realise the clamp meter won’t detect the very small drain but for the sake of this experiment I feel I’ve proven nothing terrible is occurring when it’s locked.
Cheers all - Hope you have a great weekend.
Alex
Car locked - 0.4a
Car locked (10 minutes later) 0.03a
Boot (trunk) door only unlocked - 1.4a
Car globally unlocked - 9.10a
I did hit the issue with the clamp meter going to sleep so basically had to stand there and watch it - I’m sure the neighbours think I’m mad.
My experiment was basically to ensure there wasn’t excessive drain on the battery while it was supposed to be sleeping - now I do realise the clamp meter won’t detect the very small drain but for the sake of this experiment I feel I’ve proven nothing terrible is occurring when it’s locked.
Cheers all - Hope you have a great weekend.
Alex
What you have proved Alex is that your car is behaving perfectly at 30mA after 10 minutes. Stop worrying mate.:mrgreen:
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