xorigamixartstx Posted May 31, 2012 Share Posted May 31, 2012 My 300tdi's battery runs flat if not used for a week or so. Any ideas as to what common problems may be causing this? Thanks in advance Quote Link to comment Share on other sites More sharing options...
fozsug Posted May 31, 2012 Share Posted May 31, 2012 Duff battery Alternator not putting out full charge Interior lights not going off Stereo Lights on Alarm Quote Link to comment Share on other sites More sharing options...
Boydie Posted June 1, 2012 Share Posted June 1, 2012 Unless you have left some ancillary running it will be a defective cell. The car alarm will not draw enough current to flatten a good battery, some new design battery's have a viewing window where a green colour indicated a full charge, this does not indicate a battery with a defective cell though. Quote Link to comment Share on other sites More sharing options...
xorigamixartstx Posted June 1, 2012 Author Share Posted June 1, 2012 Battery is new and has only been in a few weeks. It went dead for the second time 7 days after being fully charged. No lights left on etc. How about a duff glow plug relay is that a possibility? Quote Link to comment Share on other sites More sharing options...
BogMonster Posted June 1, 2012 Share Posted June 1, 2012 Unless you have left some ancillary running it will be a defective cell. The car alarm will not draw enough current to flatten a good battery, some new design battery's have a viewing window where a green colour indicated a full charge, this does not indicate a battery with a defective cell though. The green light is a waste of space really. I never rely on it - a voltmeter is a far better indicator of battery health. One possibility is the regulator in the alternator, if this is defective you get a drain back through it with the engine off, usually only an amp or so but it doesn't take long to drag the battery down (and it will still charge with the engine running). Best bet is to switch everything off and get a 10 amp multimeter, then carefully disconnect the battery and feed it through the meter, you should see about 30 milliamps from a typical alarm system (0.030 amps) I suspect you will see rather more than that. Somebody switching the rear light on in the back of the older Discoverys is a favourite though... and you can't see it from in the front. Quote Link to comment Share on other sites More sharing options...
Niamh Posted June 1, 2012 Share Posted June 1, 2012 We're still trying to track down a 140mA drain! Pulling every fuse in sequence doesn't remove the drain Niamh Quote Link to comment Share on other sites More sharing options...
Tanuki Posted June 1, 2012 Share Posted June 1, 2012 Disconnect the wires from the alternator. A faulty diode in the alternator's rectifier-pack can easily cause that sort of current drain. --Tanuki. Quote Link to comment Share on other sites More sharing options...
Niamh Posted June 1, 2012 Share Posted June 1, 2012 Been there... disconnected the alternator to no effect. Niamh Quote Link to comment Share on other sites More sharing options...
richard1978 Posted June 9, 2012 Share Posted June 9, 2012 A mate of mine every other day needed to jump his BMW. It turned out to be an incorrect bulb in his rear cluster which had a constant drain due to it having two elements in it. Have you tried the light circuits. 140mA may well be a lamp, horn or perhaps corrosion in and around fuse boards... hope this helps. richard Quote Link to comment Share on other sites More sharing options...
Niamh Posted June 9, 2012 Share Posted June 9, 2012 Every fuse has been pulled, the radio one drops the draw by 30mA but no other fuse has any effect. Quote Link to comment Share on other sites More sharing options...
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