battery going flat

[Roverman]

Hi lads
My 27 year old Range Rover P38A is in good nick, but I have a slight problem (I don't use it enough  ) average 30 mile a week short shopping trips and when its been stood 2 or 3 days with out use the battery needs help to turn the big lump over 4.0 litre petrol ( great engine & not to bad on petrol ) I know I'm not doing enough miles, but my question is with a fully charged battery when removing the earth lead & connecting a ammeter between earth lead & battery it only shows 2 amp discharge is that enough to flatten the battery same on a brand new battery, if I do use the truck every day no problem & the alternator is charging well.                                                        My other car 62 year old Rover P4 80 keeps going to the shows and getting a roseate & choose how long she stands between shows always starts first time                       CAN'T BEET THE OLD ROVERS               

[chippie]

For a 27 year old car, a parasitic drain of 2 Amps is too high….and will flatten any battery over time…quickly compared to a modern day car.

You early need to determine the cause of the drain….

I’d start with the alternator, pull the plug off the back ( I assume it’s a Lucas ACR style..? ) check the drain current….then start with fuses…keep monitoring the drain until the reading drops…

A quick check on any interior lights is a good start too….

[Rhubarb]

Are you measuring the "drain" within 15 minutes of unlocking or locking the Car?

As all the electronics and modules will stay live for a given amount of time.

I can't remember where the battery is on that age, but even having the bonnet open could keep it all 'live'

[Roverman]

The battery is under he bonnet at  the side of the engine so to do any checking the bonnet as to be up and doors unlocked so with the ign on dash screen reads bonnet open so the electrics are live, so with no engine running I am going to have a discharge ? so it looks like use the vehicle more or keep using the battery maintainer     

[rhyds]

One think to check is to make sure the various interior lights (glovebox/boot and so on) are turning off and on as expected. The quickest way is if you have a mobile phone or digital camera with video recording set it to record inside the boot/glovebox and shut the lid. If the light stays on the video will show you

[OldGit]

The way you're testing is going to give you some electrical activity and the 2A may well be acceptable - at least until everything has 'calmed down' after the battery has been reconnected through the ammeter.

Try this:-

Connect a jump lead between the battery -ve post and the ground point on the body, connect your ammeter across the -ve post and a different ground point on the body, close all the doors and put something heavy on the bonnet switch, go and have a brew.

Come back about 30 mins after you've done the above & remove the jump lead, the ammeter will now show the current drain with the vehicle 'asleep' - you'll need a good ammeter though as 'normal' current drain will be 50mA or less...

You won't be doing the battery any favours with that sort of usage pattern, either a trickle charger or a good, regulated high output solar panel will help - either is going to be cheaper than a replacement starter battery.

[Roverman]

Thanks OldGit I'll give it a try and depending on the reading start pulling the fuse's  

[OldGit]

Check what the fuses protect before you pull them - if it's anything that's likely to have a control module on it, you may well find the current goes up, then you have to wait for it to drop again before you can continue...

If you have an accurate voltmeter in the DC mV range, you can use volt-drop checks across the fuses without having to remove them and disturb 'the Force' - there are tables for the fuse type and volt drop which give the current draw being experienced, the ones I use are on my laptop at work though.

[valhalla]

Like what everyone above has said - these P38's are not great (even factory-fresh) for "going to sleep". The BeCM on this will not properly settle-down for at-least 20mins after every aperture has been fully closed and left that way. Lean on the bodywork, the air-suspension will come to life, and it does-so frequently even when not provoked.....

Electrical gremlins are part-and-parcel of a P38 RangeRover, and these are the majority of the issues that drove these off the roads very, very quickly. I will not touch one of these unless the owner has listened, and understood, about the potentials for large diagnostic bills, and it has been a year or so since I last had one over my threshold. IMHO, these are probably the worst vehicle electrically-wise to have to deal-with, not helped by atrocious information on wiring (it's non-existent, even to the dealers) and "hoarding of information and toolsets" by mercenary aftermarket diagnostic firms.

I would recommend one thing; do not, under any circumstance, start pulling fuses randomly, from either of the fuse-locations underbonnet or (especially) under the driver's seat. All investigations must be done non-intrusively on a P38, otherwise you will chase yourself in circles, and rue the day when you need to get a complete BeCM reset as  result.

You are looking for an average current discharge from the battery, after all has been settled-down, of anywhere less than 105mA. If you can get it down to 60-ish mA, then you're doing OK. Expect the odd spike to 300mA, as long as it goes away again.

Good luck !! 

[Roverman]

Thanks lads for all the information, I am beginning to think ill live with the problem or use it more  I have had the P38 for 2 years now and the only problem I have had was when I parked too near a radio mast and it picked up the waves and refused to start moved it down the road and all was ok had no problem since (expert valhalla sorted that out for me ) the P38 is a great truck still not done 90k in 27 years some one must have really looked after this truck and I was lucky to have bought a good un, it did have all the air suspension sorted before I bought it and its like riding round in a armchair, but has you all know to much electronics but I will live with that, I always have my old reliable P4 that never lets me down       

[valhalla]

Much like the Disco2, the P38A RangeRover is one of those vehicles where it's better to "let sleeping dogs lie" and skirt some of the deeper problems ; battery-savers and garaging can go a long way to making these reliable again !