That's low, I would expect it to drop but not below 10V to be quite honest. Maybe the starter is a bit poorly, you did mention it seems to have a flat spot.

yeah I had a flat spot yesterday but not tonight when tried it think it drops so much cause the air in system we tried it after half to a hour and got same reading as next doors

not done the fues test today but did notice the snow and ice are not on the back screen unlike the rest of the windows did notice the snow melting when landing on the window so I've removed the rear window heater fuse
is it possible for it to be on even though the switch not pushed in or ignition switched off ?

Maybe switch stuck inside so you think it off but not only an idea ---- you have removed the single wire on remote box under rear top panel behind back seat haven't you ---- my vogue would go flat overnight till I did wire unplug

yeah I've removed the rf filter wire it first thing my neighbour told me to do on it

I only wondering if switch could be relay stuck --- nothing would surprise me - my HEVAC stopped working heated windows seats etc turned out to be wiring harness under dash 🙄

thats what I was thinking so I've removed the fuse and now the snow not melting on the screen I'm going to give the battery a full charge before weekend as mate is testing the fuses for me

Have you checked to see how much current is being drawn when it is just sitting there with the BeCM asleep? That will tell you if it is normal and the battery is buggered or if something is draining it. From the amount of current being drawn it's possible to calculate the sort of thing you should be looking for. One thing that has been found to cause battery drain is corrosion inside the main interior light, so try pulling that out and unplugging it.

thanks for that @Gilbertd I'll have to give that a look I'm sure you've mentioned that before some where

I had a problem on my 2.5 P38, with the battery draining after three days while parked and locked in the drive. I have sorted it out by buying one of Martys RF filters for the remote key fob. Now it will last for two or perhaps three weeks with the alarm on. The current battery is about two years old.

Pierre3.

thats about how long mine lasts is 2-3days I'll have to find Martys Web page

www.p38webshop.co.uk

Although Marty is away, Nick (Sloth) will be producing another batch of filters although the last I heard they were waiting for another shipment of printed circuit boards.

thanks Gilbertd

karlos, it seems to be the most straightforward issue to solve in the first place, fitting the RF filter. Having read all the different possibilities as posted I would not class myself as an expert by any means, but it did seem to solve my battery going dead problem.

I would say that I don't know how long the battery would stay charged, with the car locked and the alarm on, under normal circumstances. I have a 1983 Merc 500 with a similar sized battery and that will last about a month or five weeks if I leave it locked with a key and not alarm switched on. But then it doesn't have all the electrical extras that the RR has, it's pretty basic in comparison.

And lastly, I have a 2013 Lexus IS300h, and that went flat after about 10 days or 14 days, I'm not quite sure as I have not been using any of the cars since before Christmas. Bear in mind that the Lexus is a hybrid and has a slightly smaller starter battery than a normall 2.5 petrol car.

Anyway, I would suggest trying the RF filter first, before following the really good advice from the other lads here and getting too technical. And hopefully you may get a bit more life out of the battery !

Pierre3.

You mention RF filter yet in one reply it states single wire unplugged ---- that eliminates drain --- as proved by a few So I can't see what RF filter will do in that case

OK the RF filter is unplugged it been unplugged since I brought the range rover
had a small battery on it so changed it to a 644 1000cca battery
even sat in the thing locked up to see if becm goes to sleep witch it does
I've even left it unlocked to see if it was the alarm that was draining it and still drains
I've tested everything when it ticking over and getting good voltage to and from everything
even cleaned all the earth points to see if that helps

the only things I've not done that has been advised is the fues test and looking at the interior lights connections

if anyone can think of anything eles would be appreciated

If the blue wire is unplugged from the receiver, then it has no aerial on it so it will only respond to the fob, and any other 433 MHz transmission, if it is very close. Just because the BeCM is sleeping what you don't know is if there is anything else waking it up, so it could sleep after the 2 minutes but then be woken again by something. If you've got something like a remote weather station sensor next to where you park the car, that will transmit every 5 minutes or so and will wake it up. Marty's RF Filter allows you to leave the aerial connected so the fob will work over a decent range but it checks for a valid P38 code before waking the BeCM so it doesn't respond to any other 433 MHz transmissions. Do you have multiple short range devices of any sort installed at your house or do you have a radio transmitter site anywhere in the near vicinity?

It may be nothing to do with the receiver. Easy way to check is to unplug it completely. It's got the single blue wire on it and a three way plug. Unplug the 3 way, the fob won't work (obviously) but that will discount the receiver waking the BeCM so you will then need to start looking at the actual current being drawn and start checking what circuit is drawing the current.

Where in the country are you? I used to trace problems like this for a living before I retired and still have the equipment needed.

@Gilbertd
I live in Norfolk in the UK
I've only unplugged the blue wire on the reciver i can try and totally unplug the receiver and see what that does I don't really want to spend out money on a new RF reciver if it not that if that makes to your self
I don't have no weather stations near me don't have any other short range devices installed at mine that I know of

Norfolk is pretty big, which bit? I'm just outside Peterborough.

By weather stations it could be anything like a temperature sensor with an outside sensor. If you have anyone with a greenhouse that might have one. My mate has one that detects the temp in his greenhouse with a gap of around 50 metres between the two. So it may not need to be particularly close...