How to check battery drain properly with an multi meter

[cruachan]

Hi,
I was wondering if anyone out there would be kind enough to tell me the definitive way to establish what circuit is drawing current and draining the battery on my van while not in use.
I have a multi meter and have used it plenty of times for circuit checking, continuity checks etc but not a 100% how to use the ammeter function.
The battery drains over a period of 3 to 4 days. I disconnected the +ve battery cable and hooked up the ammeter in series between the battery post and the cable thinking that would show if there was current flowing but no joy. Is this the correct method or am I missing something? I saw in another post info about checking each circuit at the fuse box. Is this a better way and if so what's the best way to do it? I figured if I was getting a reading doing it my way connected to the battery I could then pull fuses to identify the circuit that was drawing current and then take it from there.
Any help much appreciated.

[RichardF]

If you have the meter in series with the disconnected terminal and the post, it is switched to ammeter function, "DC" is selected, and the leads are plugged into the correct connections on the meter (if this is necessary), you should be reading any current flowing.

If no reading, any current could be to low to register on the meter, try switching it to a lower range if this is available.

You can test the ammeter is working by switching on a small load, such as the interior light, while connected as above.

[cruachan]

Ok, thanks for that. It seems like I was doing it the right way after all. I'll check again and test the meter as you suggest.
Thanks and Merry Xmas.

[edoh]

a few 'video' examples on this page
http://www.youtube.com/watch?v=PYUoXApI89Q" onclick="window.open(this.href);return false;

[RichardF]

Fair enough. But to avoid the performance of trying to keep the probes in contact while you pull the connector off and back onto the terminal, use alligator clip extensions, or similar, on the meter probes to maintain the connections.

[cruachan]

That's great. Had a look at the stuff on you tube and it's basically what I've been doing so I'll have another look at the problem and see what I come up with.
Thanks again.

[California Dreamin]

If you are checking 'whole car drain' by putting the ameter between pos terminal and clamp.....meter still connected... pull the fuses out one at a time until the amp draw disapears, now you know which circuit is at fault you can concentrate on that one area.

Martin

[1664]

I'd also check what the current 'limit' is on the meter. The really cheapo ones only do milliamps rather than amps (and that ain't much). I'd start with all the fuses out and replace them individually. Remember to turn off your courtesy lights as you'll probably have a door open aswell

[kevtherev]

I'd also check what the current 'limit' is on the meter. The really cheapo ones only do milliamps rather than amps (and that ain't much). I'd start with all the fuses out and replace them individually. Remember to turn off your courtesy lights as you'll probably have a door open aswell

and the radio or clock might pop up a reading

[cruachan]

Thanks all. Had to leave computer earlier. Been to see the Hobbit with my son. I didn't fall asleep once so it must have been ok.
I'll get on to checking tomorrow. Is that ok on Christmas day? Maybe not.

[phild]

Watching with interest....... had the same problem for months and not got to the bottom of it. I've resorted to disconnecting battery when not in use.

[jamesc76]

I'd also check what the current 'limit' is on the meter. The really cheapo ones only do milliamps rather than amps (and that ain't much). I'd start with all the fuses out and replace them individually. Remember to turn off your courtesy lights as you'll probably have a door open aswell

and best to use an in line fuse of about 7.5 amps as the internal fuse in a multi meter is only 10 amps and costs a lot more than a automotive fuse in line!

[jamesc76]

ooops double post, so deleted!

[Mocki]

Much easier to use a 21w indicator bulb and a couple of lengths of wire in my experience, dis connect the neg battery terminal and insert the bulb tween the battery neg terminal and chassis earth..... If the bulb lights there is a drain, the brighter the the bigger the drain.... The do the removing fuses thing till the bulb isn't lit. Won't blow any meter fuses and you won't get false readings ..... Also remember not everything goes through the fuse board...

[cruachan]

Back again,
After a bit of faffing and trying to check current, realised finally that fuse was blown in ammeter! Now fixed and working properly so back to basics with checking current at battery. Reading is 0.09amps which I presume is not sufficient to drain battery in short period of time ( but no expert ). Also double checked using bulb method ( thanks Mocki ). Bulb didn't light up but came on when I switched interior light on, also got a reading on meter when doing the same test. Maybe battery kaput? Checked the voltage this morning. 4 volts!. Recharged it off the van and will monitor voltage over next day or two to see if it's holding charge. New battery only this April so maybe a dud.
Thanks again for advice.