Battery Drain

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grinnal

Member
Posts
22
Hi Folks,

I have a 4.6 P38 that drains the battery every couple of days,this is what I have done.

New Battery
Replaced the Unit in the rear for the alarm
Tested the current draw for BCM:-
Results where after a couple of mins the current draw dropped to .27ma
Tested other car fobs etc with no effect on BCM waking up.

This leads me to think the BCM is sleeping ok.

The car is all standard.

Couple of things that would be useful to know.

What should the alternator give me?

I live in Bridgnorth Shropshire does any body know a place local that has Test book and what they charge for a diag?

Thanks

Mike
 
When you replaced the RF receiver did you buy it from a reputable supplier and/or have you opened the box and compared it to Datatek's pictures on here to ensure that it's the newest version?

Have you tried disconnecting the aerial from the R.F. receiver for a few days to see if the battery still discharges?

Have you had your alternator checked to see if the diode pack is breaking down and leaking current from the battery? Or, have you tried disconnecting the alternator whilst the car is parked up?

Are there any signs (holes in trim or spare wiring shoved out the way) of a handsfree mobile phone kit having been fitted and removed?
 
grinnal said:
Hi Folks,

I have a 4.6 P38 that drains the battery every couple of days,this is what I have done.

New Battery
Replaced the Unit in the rear for the alarm
Tested the current draw for BCM:-
Results where after a couple of mins the current draw dropped to .27ma
Tested other car fobs etc with no effect on BCM waking up.

This leads me to think the BCM is sleeping ok.

The car is all standard.

Couple of things that would be useful to know.

What should the alternator give me?

I live in Bridgnorth Shropshire does any body know a place local that has Test book and what they charge for a diag?

Thanks

Mike
Click to expand...
If the BECM is going to sleep and staying asleep, then you can discount the RF receiver, my bet would be the alternator.
You should see 14.2 volts at 2k rpm or a little more. up to 14.8 is safe. Lower than 14.2 will not fully charge the battery and may indicate diode or regulator failure in the alternator.
As others said, mobile phone and tracking device installations can also be the cause.
 
Thanks Folks,

I have dropped my Multi meter and it is boken, But I am pretty sure from a test I did a while back that it is giving 13.6 volts, will buy new meter and let you know what I find
 
Hi Folks,

I checked mine is a GEMS 1998 car that has 120amp alternator, it is giving 13.9 volts.

As this is 120 amp should I still see 14.2 volts as a min?

Thanks
 
grinnal said:
Hi Folks,

I checked mine is a GEMS 1998 car that has 120amp alternator, it is giving 13.9 volts.

As this is 120 amp should I still see 14.2 volts as a min?

Thanks
Click to expand...

If you get 13.9 at idle just after start up and then 13.9 with all services being used at 2000 rpm. It should be fine. 14.2 is the absolute maximum voltage the alternator can deliver as controlled by the output regulator.
 
grinnal said:
Hi Folks,

I checked mine is a GEMS 1998 car that has 120amp alternator, it is giving 13.9 volts.

As this is 120 amp should I still see 14.2 volts as a min?

Thanks
Click to expand...

As wammers said that might be OK but with no load apart from the battery it should rise at 2K rpm to 14.2 volts. However that assumes an original LR fitted alternator, regulators are available from 13.2 to 15.2 volts and 13.9 is a common one for older batteries. It will not fully charge a modern low/no maintenance battery.
worth checking the voltage at the alternator as you may have a connection problem but that would not account for battery discharge. However if the battery is not fully charging the time to flat will be greatly reduced and the battery may suffer premature failure.
 
Last edited:
Hi Folks

I fited a new Alternator Desso 120amp from island 4*4 and got the 13.97 volts when doing 2000rmp.

So this is the same as my previous alternator.

I did another amp test and after two mins it drops to between 27 - 30 ma.

I have tried several other key fobs garage door remote ect and the car sits at 27 -30 ma.

What should I see from the battery on it's own?

I am wondering if the battery damages as a result of draining before I changed the Remote unit.

It does have an idicator on the battery that says it is ok

Cheers
 
I have a 4.6 Vogue 2000(Y) and my battery which has been tested as fine is draining 5 amps! Leading to either the engine being immobilised or a flat battery more and more frequently especially when it's very cold. For some time now the indicator lights are flashing intermittently when the car is parked but no alarm is sounding. The car will only start using a strong jump pack or jump leads. I was told I could have a faulty becm by one garage who bypassed it to fix a heater problem. My current garage thinks it COULD be a faulty becm but has not investigated it. I have been stuck in a notorious area for bad mobile signal and from the threads I have read am veering towards the RF receiver being at fault. Would this sound possible? I have a hands free parrot fitted and reversing indicators also. Not sure if these could cause a problem?
 
grinnal said:
Hi Folks

I fited a new Alternator Desso 120amp from island 4*4 and got the 13.97 volts when doing 2000rmp.

So this is the same as my previous alternator.

I did another amp test and after two mins it drops to between 27 - 30 ma.

I have tried several other key fobs garage door remote ect and the car sits at 27 -30 ma.

What should I see from the battery on it's own?

I am wondering if the battery damages as a result of draining before I changed the Remote unit.

It does have an idicator on the battery that says it is ok

Cheers
Click to expand...
Sounds like it could be the battery, they do self discharge rapidly in the cold if they are starting to fail. If the battery has frequently gone flat, it will have suffered, they are not designed for deep discharge cycling. The battery drain at 27 - 30 ma is normal.
 
Catwoman said:
I have a 4.6 Vogue 2000(Y) and my battery which has been tested as fine is draining 5 amps! Leading to either the engine being immobilised or a flat battery more and more frequently especially when it's very cold. For some time now the indicator lights are flashing intermittently when the car is parked but no alarm is sounding. The car will only start using a strong jump pack or jump leads. I was told I could have a faulty becm by one garage who bypassed it to fix a heater problem. My current garage thinks it COULD be a faulty becm but has not investigated it. I have been stuck in a notorious area for bad mobile signal and from the threads I have read am veering towards the RF receiver being at fault. Would this sound possible? I have a hands free parrot fitted and reversing indicators also. Not sure if these could cause a problem?
Click to expand...
:hijacked: and no introduction, see your other post.
 
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