Battery Drain Again

Hi guys

Have searched and tried all ive found but still no joy.
Anyone got any ideas? Would really appreciate any advice.

1996 RR 2.5 DSE 188k ..2 month ago i was getting wifi interferance and batt drain, so have disconnected the aerial to the reciever..All been good until 2 week ago. by pressing remote by rear window.

The car will crank and start all ok. If you leave the door open or headlights on for 5mins without engine running,the battery is dead flat..Have replaced battery and had the new one drop tested. The alternator is throwing out 14.5v when running and the car stopped and started all ok..

Last week im now finding the battery is dead flat if left over night..So im going through the process of disconnecting the earth lead each night, and the battery all holds charge ok..

Is there any fuses i can start pulling to illiminate discharge? I.e central locking or radio etc..Some people are suggesting the alternator diode? Can i unplug the alternator plug over night to illiminate this? ..Im having knightmares it could be BECM as the age and mileage are creeping on.

Im getting a very very minor spark as i attach earth lead, so the drain cant be that big?

Would really appreciate any advice guys,
Thanks in advance
Tel

Interior lights left on overnight can flatten a battery and you won't get much of a spark on connecting the battery. I think that the standard battery drain with the BECM asleep is about 30 Milliamps. Connect a test meter set to 10 amps between the eart lead and the battery and measure just how much current is being drawn. I reckon it's still likely the RF receiver keeping the BECM awake as you have had trouble with it. Do yourself a favour and replace with the latest version. Lots of threads on here about checking if the BECM is going to sleep.

Thanks for the advice Datatek

Have just set the multi meter to "10A" and connected between the Earth lead and - Battery terminal and im getting a reading of -0.81

Can the RF still drain the battery even if the aerial is disconnected?
The battery drain is where ever i park, not just in certain locations where i used to get problems.

Thanks mate.
LTel

Boydonegood said:

Thanks for the advice Datatek

Have just set the multi meter to "10A" and connected between the Earth lead and - Battery terminal and im getting a reading of -0.81

Can the RF still drain the battery even if the aerial is disconnected?
The battery drain is where ever i park, not just in certain locations where i used to get problems.

Thanks mate.
LTel

Click to expand...

If the RF receiver is faulty, I reckon it's quite possible it could keep waking up the BECM even with the aerial disconnected. Replacing it would be my first step as you have already had trouble with it. There are threads on here about how to see if the BECM is awake but 0.81 amps would be about right if the system is awake I think. Others like Irish may correct me on this.

Guys
Sorry to bring this one back to life.

Have fitted the new RF Reciever £173 Ouch!!
Still having the exact same problem..If i take the battery off of a night and reconnect the next morning, resync the key fob and all starts ok..

Disconnect the battery,wait 5 mins and connect a Amp meter and its showing a drain of 0.8.

My theroy is to park it tonight, disconnect the battery then pull out every fuse and relay under the bonnet and under drivers seat.also the alternator.then reconnect batt and see what happens in morning..

I know this wont identify what is draining it (but should mean its fixable?)

The only thing im worried about is ive read stories about the ECU loosing sync? Is there anything i really shouldnt unplug?

Any help would be appreciated..Cheers guys

Tel

Boydonegood said:

Guys
Sorry to bring this one back to life.

Have fitted the new RF Reciever £173 Ouch!!
Still having the exact same problem..If i take the battery off of a night and reconnect the next morning, resync the key fob and all starts ok..

Disconnect the battery,wait 5 mins and connect a Amp meter and its showing a drain of 0.8.

My theroy is to park it tonight, disconnect the battery then pull out every fuse and relay under the bonnet and under drivers seat.also the alternator.then reconnect batt and see what happens in morning..

I know this wont identify what is draining it (but should mean its fixable?)

The only thing im worried about is ive read stories about the ECU loosing sync? Is there anything i really shouldnt unplug?

Any help would be appreciated..Cheers guys

Tel

Click to expand...

Have you considered that the regulator pack in the back of the alternator my have a stuffed diode, this can sometimes cause the battery to drain overnight.

Boydonegood said:

Guys
Sorry to bring this one back to life.

Have fitted the new RF Reciever £173 Ouch!!
Still having the exact same problem..If i take the battery off of a night and reconnect the next morning, resync the key fob and all starts ok..

Disconnect the battery,wait 5 mins and connect a Amp meter and its showing a drain of 0.8.

My theroy is to park it tonight, disconnect the battery then pull out every fuse and relay under the bonnet and under drivers seat.also the alternator.then reconnect batt and see what happens in morning..

I know this wont identify what is draining it (but should mean its fixable?)

The only thing im worried about is ive read stories about the ECU loosing sync? Is there anything i really shouldnt unplug?

Any help would be appreciated..Cheers guys

Tel

Click to expand...

Altenator, Diodes, as mentioned earlier i believe. Why do people ask for advise and then not act on it? Apart from the obvious, lights left on, they are the number one cause of battery drain. Also the battery should not be dead flat after having lights on for five mins. Unless you have a battery from a lawn mower on it.

Maplins do a cheap (and good) bit of kit to enable you check circuit drain - plugs into each fuse position, for less than a tenner .

Sorry guys
Forgot to mention, whilst checking it the other day with the meter connected it draws 0.8 A .... I tried pulling all the fuses and it still didnt change..
I also disconnected the alternator at the same time and the drain was the same, id presume this eliminates the alternator diode pack being faulty. Was going to remove them again tonight to make sure.

I pass a Maplins on way home,, will deffo go and collect one..Many Thanks

Cars begining to become a liability now,

Really hopeing its not BECM

Cheers LTel