Measuring Power Drain?

[Fishey]

Anybody know how i can measure the drain from my battery when the car is not running? And also what sort of drain should there be, as obviously there is constant power going to a few things.

 

[mr bognor]

D.m.m

 

[gav182]

you ll need either an amp clamp or an ammeter in series . shouldn t get more than 500 milliamps or 250 on a newish car .

 

[edde]

Shouldn't be any drain sounds liek you've a wiring problem easy way it to unplug bits until the drain stops.

Check the batterys any good might just be worn.

 

[Dink]

yeah a dc clampmeter would be the best way to measure

 

[Fishey]

cheers, just the battery i always flat, the battery is testing fine, the charge to the battery is fine and the earths seem to be fine!

 

[BrianR]

You need to put a DMM (digital multi meter) in line with the battery to read small amounts of current; a clamp is not sensitive enough unless you have an oscilloscope.

Set the DMM to read current (amps) and remove the positive lead from your battery. Connect the positive battery terminal to the black (neg) lead on the DMM and the red (pos) lead of the DMM to the Pos. battery terminal.
You will now be reading the current.

When the car is switched off, the reading should only be a few mA. Showing the current drawn by your immobiliser LED and the clock/radio back up.

I haven’t tested a Clio recently so I don’t know what they draw but more than 20mA and I would want to know why.

Check how the reading rises when you operate the interior light by opening the door, you should be able to calculate it to check. 5w bulb draws 350 mA

Don’t switch anything like headlights or heated screen on as you meter leads could get hot and melt. If you need to measure these sort of currents, a clamp is the best way.

 

[Fishey]

thats just what i needed to no, cheers!