Checking battery drain on car with lots of electrics

longwalks1

As in my other thread currently running, having a battery drain issue with my Range Rover TD6. I want to measure to see if theres any drain once its turned off, I understand you need to leave it 15 minutes for everything to shut down and go to sleep (the ECU's etc), then what would I do to test for any drain?

Someone at work suggested a clamp meter around the negative cable from the battery, but i did read it may not read such a small drain (mA) on a car.

Any ideas please people?

TrickyWicky

You need a multimeter to measure the current drawn from the battery. Take off the positive terminal, put the red probe on the batter and then the negative probe on the battery terminal/wire that is no longer connected. The meter will measure the current being drawn through it by the car.

Be warned though, there are several issues with this:
Intermittently touching the probes on the contacts might screw things over so you need firm solid contact
You need to understand the difference between amps, milliamps, microamps etc to know what it's drawing
You need to know what it SHOULD be drawing to know if its normal or not - eg by measuring another car or being told by the manufacturer.

Your best bet might be to get a battery load test done instead to see if the battery condition is good.

garethgas

If the battery is good then you already know you have a power drain so carrying out the above procedure is only going to confirm what you already know.
I suggest a current tester which will identify the circuit which is faulty and therefore at least move you closer to fixing the problem
http://www.maplin.co.uk/automotive-current-tester-217879

Strider590

Meh, turn car off, access the fuse box, start from the top, pull out a fuse, insert multimeter (in current mode) into the fuse terminals and measure current, made a note, remove meter, replace fuse, rinse/repeat until all have been tested.

In all honesty though, it's probably something daft like the boot or glove box light not turning off.

garethgas

Strider590 wrote: »

Meh, turn car off, access the fuse box, start from the top, pull out a fuse, insert multimeter (in current mode) into the fuse terminals and measure current, made a note, remove meter, replace fuse, rinse/repeat until all have been tested.

In all honesty though, it's probably something daft like the boot or glove box light not turning off.

Yes, that's exactly what the current tester does but with a more reliable connection to the inside of the fuse terminals.
You might also try starting from the bottom...its always the last one!:D

Notmyrealname

britishboy wrote: »

As in my other thread currently running, having a battery drain issue with my Range Rover TD6. I want to measure to see if theres any drain once its turned off, I understand you need to leave it 15 minutes for everything to shut down and go to sleep (the ECU's etc), then what would I do to test for any drain?

Someone at work suggested a clamp meter around the negative cable from the battery, but i did read it may not read such a small drain (mA) on a car.

Any ideas please people?

Get a multimeter. Put it on Current. Disconnect the earth terminal on the battery. Put one of the probes on the disconnected earth terminal and the other on the earth terminal on the battery.

Notmyrealname

TrickyWicky wrote: »

You need a multimeter to measure the current drawn from the battery. Take off the positive terminal, put the red probe on the batter and then the negative probe on the battery terminal/wire that is no longer connected.

Not the positive, you do it with the negative so that way if you touch the bodywork with the spanner/screwdriver you don't end up shorting the battery.

The_Slithy_Tove

Notmyrealname wrote: »

Get a multimeter. Put it on Current. Disconnect the earth terminal on the battery. Put one of the probes on the disconnected earth terminal and the other on the earth terminal on the battery.

Best to connect the meter up with the earth strap still connected, and then remove the strap. That way, there's no interruption in current to whatever systems are running, so you'll get a better indication (i.e. no current drain from systems starting up from a power-down state).

Also, make sure (pretty much) everything is off first - you don't want to be pulling 30A through a meter that is only rated to 3A (for example).

longwalks1

garethgas wrote: »

If the battery is good then you already know you have a power drain so carrying out the above procedure is only going to confirm what you already know.
I suggest a current tester which will identify the circuit which is faulty and therefore at least move you closer to fixing the problem
http://www.maplin.co.uk/automotive-current-tester-217879

Cheers gareth
Silly question do i use the tester while car is turned off? (sorry having a blonde day today)

Strider590

britishboy wrote: »

Cheers gareth
Silly question do i use the tester while car is turned off? (sorry having a blonde day today)

If the problem occurs when it's off, then you need to recreate that condition.