So I have a nasty little drain. It takes between 5-6 days before the old girl runs down to a point she won't crank. The battery is new and takes a charge off of the alternator as confirmed by a meter, not the dubious dash. The battery light is pretty temperamental for the first 5mins of running before it clicks off and stays off. Battery terminals are clean and solid.


I am kind of resigned to an afternoon of logic, metering and strong coffee to identify a the constant and unwelcome draw, but does anyone have any advice on where to start? For the record I have recently rebuilt the ignition (cap / leads / coil and plugs) the earths in the engine bay are clean, tidy and secure and I also had to replace the nasty plastic strip fed aerial array - other than that I not touched anything to do with electric worm.


Advice appreciated. (85 v12)

 

If you are trying to find a drain on battery try this. Disconnect battery and place an amp meter between battery and wiring. Note amp draw. Disconnect 1 fuse at a time and check reading. The draw will go to zero when fuse pulled. Now you have identified the circuit. From there move meter to that location if fuse panel and work the circuit until you find the draw. A bit of a Pain in the a$$. but it works.

 

A common problem. As mentioned, the ammeter and fuse pull is the only surefire way. But if you want a suggestion on the most common 4 causes:

- Boot light (most likely)
- Radio aerial
- Alarm system (possibly not applicable to your year)
- Alternator diode drain

Good luck

Paul

 

Quick easy way is to pull the negative cable and put a test light in between the neg cable end and the neg post. Ensure the boot light switch is depressed and if the in line light is lit there is a drain. Disconnect the Ariel power and see if it goes out, still on, leave the boot open and the boot light out and start pulling fuses one at a time till the in line light goes out. The nice thing about using a bulb in line is you can see it from the cabin so you don't have to keep coming around to check it. You have to make sure the boot light is out as well as the dome lights when the cabin doors open as these are drains and will add to confusion.

 

Another very simple way to begin. Go through the car and feel as many relays as you can find. See if any are warm. I found my drain that way, in the trunk, the antenna mast relay was quite warm to the touch.

 

recently I replaced the rubber on the boot. after that my battery would go after about 4 or 5 days. Since the boot lid was closing a bit harder than before I placed my camera on video, placed it in the boot and found out the lights were staying on. change the rubber back over and all was fine