P38A what flattens P38 batteries?

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Sonnycbr

Active Member
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Hello, I recently left my 2000 P38 4.6 petrol for about a week and the battery didn't have enough power to start the car. It started straight away from a jump start from a heavy duty battery. What can be draining the battery so quick? I have to park the car up for 2 weeks next April at Edinburgh airport, any ideas on what I can do to ensure I can start the engine and get home? Thanks in advance.
 
Sonnycbr said:
Hello, I recently left my 2000 P38 4.6 petrol for about a week and the battery didn't have enough power to start the car. It started straight away from a jump start from a heavy duty battery. What can be draining the battery so quick? I have to park the car up for 2 weeks next April at Edinburgh airport, any ideas on what I can do to ensure I can start the engine and get home? Thanks in advance.
Click to expand...
Out of interest you had the car long ? All sorts of things drain the battery try doing a search on here (if its working that is) all sorts of reasons will pop up.
 
Old dying battery? Cold weather usually finds them out.
You need to fully recharge it with a battery charger, driving around won't do much.
Parasitic battery drain due to something in the car not shutting down properly?
Known issue with the P38 of spurious RF signals waking the BECM. IIRC one way is to remove the small aerial from the receiver.
Been covered on LZ e.g: https://www.landyzone.co.uk/land-rover/the-new-rf-box-ywy500170.232779/
& also here: https://www.rangerovers.net/repairdetails/electrical/batdrain.html
 
Ratae said:
Old dying battery? Cold weather usually finds them out.
You need to fully recharge it with a battery charger, driving around won't do much.
Parasitic battery drain due to something in the car not shutting down properly?
Known issue with the P38 of spurious RF signals waking the BECM. IIRC one way is to remove the small aerial from the receiver.
Been covered on LZ e.g: https://www.landyzone.co.uk/land-rover/the-new-rf-box-ywy500170.232779/
& also here: https://www.rangerovers.net/repairdetails/electrical/batdrain.html
Click to expand...
I've had the car two years. The battery is about 9 months old. I did a search on batteries on here and to be honest, got totally bamboozled.
 
I mentioned eurocarparts 'Lion' brand batteries in another thread. Around 9 months was about their lot & as soon as it got cold. Not got one of those?
 
With any range rover the rule is put the biggest ah highest cca you can fit in there, on a P38 that will be 120ah 1000cca especially if you have a diesel.
one cause of drain is the RF unit receiving rouge signals and keep waking up the Becm, there are three options there JLR`s £240+ new receiver ,

@martyuk has come up with a new replacement unit that is about £90 or if you want some thing a bit cheaper you can fit an extra remote jog switch
here is the details but fist you must ensure the battery is 100% ok
https://www.landyzone.co.uk/land-rover/rf-reciever-work-round.258096/
 
A solar panel on the rear parcel shelf will keep the battery topped up, but as others have said there are several well documented sources of battery drain and batteries also self discharge as they start to die.
 
Raindrops on roses and "just click's on key starts".....

What flattens P38 batteries? P38's.
RF interference and an insomniac BeCM.
Short "to the shops & back" journeys with 2 starts no long runs to recharge.
Weak Battery, poor Alternator.
Poorly fitted aftermarket items that stay live even when the car is "off".

These are a few of my least favourite things.
 
brianp38dse said:
With any range rover the rule is put the biggest ah highest cca you can fit in there, on a P38 that will be 120ah 1000cca especially if you have a diesel.
one cause of drain is the RF unit receiving rouge signals and keep waking up the Becm, there are three options there JLR`s £240+ new receiver ,

@martyuk has come up with a new replacement unit that is about £90 or if you want some thing a bit cheaper you can fit an extra remote jog switch
here is the details but fist you must ensure the battery is 100% ok
https://www.landyzone.co.uk/land-rover/rf-reciever-work-round.258096/
Click to expand...
Thanks for all the replies. I've checked the battery and its a Varta 95Ah, 830A. It's been fine till it was left for a week. I'm undecided which route to go down, I'm leaning towards a jump pack as I have bikes and other cars that might benefit one day.
 
You can pull the blue Arial lead of the rf reviewer this will help a bit to stop the car waking up, just mens you have to use your key fob by the drivers side rear window to unlock the car,
This is assuming that the becm is the battery drain and not anything else and your battery is 100%.
 
If you have an auto, then sit in it with the doors closed when it gets dark (don't need to be locked) and look at the gear indication LED next to the shifter. It will be glowing dimly when the BECM is awake, and should extingush after a couple of minutes. If it doesn't go out, then something is keeping the BECM awake (and drawing around 1A of power, vs 30mA ish when it's sleeping). If it goes out and then comes back on again within 5-10mins, then the BECM is sleeping and something is then waking it up (usually RF).

A 95AH battery, if fully charged and healthy should in theory be able to deliver 95A of current for 1hour - or 1A of current for 95 hours (in reality it never works out like this! - especially in a P38) - but if your BECM is sleeping, but being woken regularly, then it could easily explain why the battery is flat in 5 days. If BECM is awake all the time, it can go flat in as quick as 2-3 days to the point where it wont start the vehicle.

If you get the shifter LED going out and coming back on again, then you can do as suggested by brianp38dse and pull the antenna wire off the RF receiver and see if that makes a difference. If you want to rule in/out RF altogether then you can disconnect the main power/signal connector to the RF receiver and then repeat the test. If the BECM then sleeps, and doesn't wake up again in the same period that it would before, then you've found your issue. If it still doesn't sleep then something else is causing it (either something aftermarket, dodgy door microswitch etc - there are a number of activation inputs that will keep a BECM awake).

If it does boil down to RF - also ad brianp38dse mentions, there are a few options now, including the RF filter myself and another P38 owner have developed, or the second fob/relay idea to be able to disable the rf receiver

I'd be sitting in it to see if it sleeps first... if it's a manual, then this test won't work, and you'll have to go with a different test - either with a DC clamp meter around the main +ve cable, or a multimeter in series with the power or ground wire to measure current draw.

Battery - I only recommend the MF31-1000 range (Battery Megastore has them branded as Hankook at the moment) or a Yuasa 664SHD (or other type 664). They're the biggest that will fit in the battery tray, and are about 115-120Ah, 1000CCA units.

EDIT - I re-read and see it's a 2000 Thor - so should be an auto, and you can do the 'sit in it' test...
 
Yes, the RF Filter is finished and available on my website - at the moment we are having to make them a couple at a time - as I'm away still and my mate works full time aswell, but they are available and work.. I think there are about 15-16 of them out there now.

My work schedule lately had been crazy - I've had 3 nights at home since the start of November! So I haven't had time to sit down and do a write-up on it yet, but I get home on Tuesday, so will try and put a post up then about what it is, what it does and all that. My mate Nick did a bit of a video demonstrating some of the things regarding the RF interference, and also having the filter fitted and it working. The video is on youtube and can be found here:


I promise that once I'm back I will do a proper write-up though... I'm also hoping to catch up with my mate in person and spend an evening building a load of the filters, so we have some decent stock levels so we can list them in various places! The next project on the list is to work on key fobs - but that's another story...

Marty
 
Total faith in it and @martyuk so have ordered a filter today.
The jog unit has done a great job but 2 remotes on my keyring means a bulging pocket that makes it look like I have a permanent hard-on.
Also, doing a 1..2 with 2 fobs is a faff. So I am grateful for a less fiddly non LR solution.

Ta muchly!
 
martyuk said:
If you have an auto, then sit in it with the doors closed when it gets dark (don't need to be locked) and look at the gear indication LED next to the shifter. It will be glowing dimly when the BECM is awake, and should extingush after a couple of minutes. If it doesn't go out, then something is keeping the BECM awake (and drawing around 1A of power, vs 30mA ish when it's sleeping). If it goes out and then comes back on again within 5-10mins, then the BECM is sleeping and something is then waking it up (usually RF).

A 95AH battery, if fully charged and healthy should in theory be able to deliver 95A of current for 1hour - or 1A of current for 95 hours (in reality it never works out like this! - especially in a P38) - but if your BECM is sleeping, but being woken regularly, then it could easily explain why the battery is flat in 5 days. If BECM is awake all the time, it can go flat in as quick as 2-3 days to the point where it wont start the vehicle.

If you get the shifter LED going out and coming back on again, then you can do as suggested by brianp38dse and pull the antenna wire off the RF receiver and see if that makes a difference. If you want to rule in/out RF altogether then you can disconnect the main power/signal connector to the RF receiver and then repeat the test. If the BECM then sleeps, and doesn't wake up again in the same period that it would before, then you've found your issue. If it still doesn't sleep then something else is causing it (either something aftermarket, dodgy door microswitch etc - there are a number of activation inputs that will keep a BECM awake).

If it does boil down to RF - also ad brianp38dse mentions, there are a few options now, including the RF filter myself and another P38 owner have developed, or the second fob/relay idea to be able to disable the rf receiver

I'd be sitting in it to see if it sleeps first... if it's a manual, then this test won't work, and you'll have to go with a different test - either with a DC clamp meter around the main +ve cable, or a multimeter in series with the power or ground wire to measure current draw.

Battery - I only recommend the MF31-1000 range (Battery Megastore has them branded as Hankook at the moment) or a Yuasa 664SHD (or other type 664). They're the biggest that will fit in the battery tray, and are about 115-120Ah, 1000CCA units.

EDIT - I re-read and see it's a 2000 Thor - so should be an auto, and you can do the 'sit in it' test...
Click to expand...
Thanks for that Marty, I'll be out soon sitting in the car, in the dark, like a total pervert! I've just watched the vid for the filter that you've developed and I'll be ordering one if necessary. Thank you again for your help.
martyuk said:
If you have an auto, then sit in it with the doors closed when it gets dark (don't need to be locked) and look at the gear indication LED next to the shifter. It will be glowing dimly when the BECM is awake, and should extingush after a couple of minutes. If it doesn't go out, then something is keeping the BECM awake (and drawing around 1A of power, vs 30mA ish when it's sleeping). If it goes out and then comes back on again within 5-10mins, then the BECM is sleeping and something is then waking it up (usually RF).

A 95AH battery, if fully charged and healthy should in theory be able to deliver 95A of current for 1hour - or 1A of current for 95 hours (in reality it never works out like this! - especially in a P38) - but if your BECM is sleeping, but being woken regularly, then it could easily explain why the battery is flat in 5 days. If BECM is awake all the time, it can go flat in as quick as 2-3 days to the point where it wont start the vehicle.

If you get the shifter LED going out and coming back on again, then you can do as suggested by brianp38dse and pull the antenna wire off the RF receiver and see if that makes a difference. If you want to rule in/out RF altogether then you can disconnect the main power/signal connector to the RF receiver and then repeat the test. If the BECM then sleeps, and doesn't wake up again in the same period that it would before, then you've found your issue. If it still doesn't sleep then something else is causing it (either something aftermarket, dodgy door microswitch etc - there are a number of activation inputs that will keep a BECM awake).

If it does boil down to RF - also ad brianp38dse mentions, there are a few options now, including the RF filter myself and another P38 owner have developed, or the second fob/relay idea to be able to disable the rf receiver

I'd be sitting in it to see if it sleeps first... if it's a manual, then this test won't work, and you'll have to go with a different test - either with a DC clamp meter around the main +ve cable, or a multimeter in series with the power or ground wire to measure current draw.

Battery - I only recommend the MF31-1000 range (Battery Megastore has them branded as Hankook at the moment) or a Yuasa 664SHD (or other type 664). They're the biggest that will fit in the battery tray, and are about 115-120Ah, 1000CCA units.

EDIT - I re-read and see it's a 2000 Thor - so should be an auto, and you can do the 'sit in it' test...
Click to expand...
 
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