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Vehicle & Technical => Range Rover => Topic started by: yellow series 2a on October 08, 2009, 17:27:43

Title: Battery going flat overnight on RR p38 any ideas!!!
Post by: yellow series 2a on October 08, 2009, 17:27:43
HI
I have a 1997 RR p38 4.0 SE and if the car is left for more that 24 hours the battery goes flat,  but if you charge the battery up and use the car everyday there is no problem!!, i have just brought a new battery as well! Please Help!

Many Thanks Laurence
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: Brett69 on October 08, 2009, 17:50:07
you must have a drain on the vehicle somewhere. this can be very very difficult to find. i disconnect the negative on battery an put a large wattage 12v bulb inline to power the car back up, if it  illuminates then you have a drain, remove fuses one by one til the bulb goes out that is then the circuit you drain is on ;)
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: yellow series 2a on October 08, 2009, 18:15:37
I will try that 2moz Cheers! :)
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: auf_wiedersehen_pet on October 08, 2009, 20:24:04
put a large wattage 12v bulb inline

What sort of wattage? (No pun intended)

100w? 60w?

 :roll:
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: dod51e on October 08, 2009, 23:35:27
Simply removong fuses may not identify the problem.  I only say this as I had a drain on my Jag that killed the battery in about five days.  I did the fuse bit and a multimeter and found nothing changed, although it did confirm that there was an excesive drain.  Turned out to be a module that was not going into sleep mode.  If the fuse trick does not work then it will need to go on a full diagnostics tester as the P38 is full of electrickery!
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: Brett69 on October 10, 2009, 22:47:16
I just use a 12v 10w bulb you shouldn't need much bigger than that. I've just brought myself a P38 DSE Got back from a 450mile trip to collect it. needs work but really pleased with it for the price I paid  :grin:
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: Rossko on October 11, 2009, 23:02:07
Mystery battery drain on P38 is usually due to the alarm system being put in "high alert" by some local radio interference, without setting it off.
Typical causes ; airport ground radar, wireless networks, ... see
http://forum.landrovernet.com/showthread.php?t=99536
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: waveydavey on October 12, 2009, 20:10:32
Mystery battery drain on P38 is usually due to the alarm system being put in "high alert" by some local radio interference, without setting it off.
Typical causes ; airport ground radar, wireless networks, ... see
http://forum.landrovernet.com/showthread.php?t=99536

What he said: they are well known for it. Basically the BeCM goes to sleep and has minimal power drain, if it gets a signal forma  key it wakes up to interrogate it and that uses a lot more power as the whole BeCM is awake.
The problem is that the BeCM sees all sorts of things as keys and can wake up too often.
Title: Re: Battery going flat overnight on RR p38 any ideas!!!
Post by: charlie420 on October 14, 2009, 22:07:12
check the alternator charge mine would be fine for days when used but then af left for a few days battery would be flat alt was only charging at 11 volts i turned the idle speed up a bit now reads 13ish all the time and no more battery issues even when left for a few weeks
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