Battery drain?

Hello Everyone

I have a PT Cruiser 06, a CRD (diesel) Route 66, I have had it nearly a year now

I recently had a problem with my battery, (which is located under the passenger seat) it was just very sluggish starting in the mornings, what with the frost and snow (okay, it werent as bad as the US)

So I ordered a nrew battery, it came next day, fast service

I installed the new battery, and the first day it was fine, the next day is was dead as a door nail

I was told I had a ‘battery drain’ on it,

I dont think I had one before, but no problem,

I took it to my mechanics, and he put it on a booster battery, all day and over night, he said no problems, it was fine, and he showed me, starting it with the booster pack (if there was a drain, I assume it would have drained the booster pack and wouldnt have started it)

I took the battery out and put it on charge, not a problem, it charged fine, I re-installed it, it started fine, tried it every hour or so, to see if there was a drop, it started fine for the first 2-3 hours, just been out now, its dead again, the reading on my ‘fluke’ volt meter is 11.6 volts, the battery light is on the dash,

I have nothing on, no interior lights, no radio, no blower, but it just clicks and beeps away, the remote locking still works (so I guess there is still enough of a charge in it, to work that)

The alternator is fine, I checked that while I was driving with the meter connected, it read 14.8volts, when I stopped the readings dropped down to a decent 12.5 volts

Has anyone any idea how and why I should develop a battery drain and even more importantly, how do I trace it and stop it ?

At present I have to disconnect the battery overnight and reconnect in the morning to get to work (work BEFORE work )

any help/advice would really be appreciated


(the ‘new battery’ has now been picked up and sent away for ‘testing’ )

I have chargeed up and now put the old one back on, to see how I get on

Sorry I forgot to mention, I am in the UK, London, I hope someone can help ?

A drain on the electrical system is very hard to diagnose without a “hands on” approach. Every connector, motor, switch, relay or bare wire against a ground can cause a drain on the battery. Water can also get into connectors and receptacles and drain the battery. A good mechanic should be able to track it down but they must be determined. A hit and miss approach will not work.

Does your Fluke have an ammeter?

Make sure all lights and accessories are off.
Put the ammeter in series with the battery.
Give it a few minutes for whatever electronics to go “asleep”.
The current should drop below ~0.2 amp, preferably under 0.1 amp (100mA)
If not pull fuses one by one until the current drops to normal.

I recently did this for my neighbor and her recently purchased BMW.
The current was ~100mA except for a short 7 amp pulse every 10 seconds or so.
Turned out to be one of the electric seats.

Circuit smith is right. The actual spec on that car is 35 milliamps draw (.035 amps). A litrtle easier and faster way yto find your draw would be to set the ammeter up as described before. Instead of pulling fuses try and get your hands on a second voltmeter. set it to millivolts. measure across the fuses, and unless you get a reading of 0.000mv there is voltage being eaten on that circuit. Also it helps to break the electrical system into sections.