C

cvloenen

Member
Hi all,
I'm suspecting my P38 2.5 diesel may have a battery drain problem. Either that or the battery is discharging itself revatively rapidly and needs replaced.
On doing an Amp test over the negitive terminal and its lead the following was observed. Approx 0.75A when key taken out and doors shut, approx 2mins later a drop to 0.5 and there it stays steady. I assume the drop is after the BECM shuts down, and is indicating it is going to sleep.

Is 0.5A normal when car is a sleep, or is it unacceptabley high and is it likely to be the cause of flattening my battery?

From fully charged my battery looses the power to start the car after about 1 week sitting.

Thanks Ian
 
cvloenen said:
Hi all,
I'm suspecting my P38 2.5 diesel may have a battery drain problem. Either that or the battery is discharging itself revatively rapidly and needs replaced.
On doing an Amp test over the negitive terminal and its lead the following was observed. Approx 0.75A when key taken out and doors shut, approx 2mins later a drop to 0.5 and there it stays steady. I assume the drop is after the BECM shuts down, and is indicating it is going to sleep.

Is 0.5A normal when car is a sleep, or is it unacceptabley high and is it likely to be the cause of flattening my battery?

From fully charged my battery looses the power to start the car after about 1 week sitting.

Thanks Ian
Click to expand...

I seem to recall somebody quoting a similar figure as being 'normal' - however, even with a good battery it will eventually go flat - 0.5 amps from a good 100Ah battery will take around 8 days to flatten it.
 
Half an amp is high. You should be seeing more like 0.05.
I haven't got the best battery in the world but mine will hold for two weeks and then start the car with no problem.
Then there is the famous issue with the remote. The receivers for these (RF receiver) are notorious for being affected by other signals and waking the BECM at random times.
But first I'd double check then try and find what's drawing that half amp.
 
The battery drain figure should be 0.030A (30 milli amps) according the LR when the BECM has gone to sleep.
 
Hi all,

I did already try unpluggin the rf reciever, which has made no difference.

I've read that 0.5A would be normal for some cars. Supprised to 0.05- 0.03A more normal?
Perhaps I'm not reading multimeter correctly! With the meter set at 20A scale, I get 0.5 on display?

Thanks Ian
 
Last edited:
cvloenen said:
Hi all,

I did already try unpluggin the rf reciever, which has made no difference.

I've read that 0.5A would be normal for some cars. Supprised to hear from Dogsbody 0.05A more normal?
Is there anybody else that cuold confirm either?

Thanks Ian
Click to expand...

0.5A is not possible, there would be dead cars in airport carparks all the time:eek:
 
Not wishing to teach you to suck eggs - but it does happen - you are taking the reading correctly...??

The only way without a clamp-on meter to measure Amps is to place the meter in series with the battery....

i.e. Disconnect Negative Earth Strap lead, Attach Red Meter Lead to Earth Strap Lead, Attach Black Meter Lead to Battery Neagtive Terminal...and for Gods sake don't start the car....!!!
 
Try doing that test and pull the fuses one by one and see if the figure goes down. That will tell you if it's shorting out anywhere.
 
I am suspecting I may be reading the multimeter wrongly. what I get on drain on the digital scale is 0.5 when meter set to 20Amps. I don't/can't get instrauctions for the meter as its old. However since the normal is around 0.005 I thinks this is what I'm getting. If I take out the clock fuse I get a drop of 0.1 on my meter which may be 0.01Amps does this sound about right to anyone? Bringing my meter reading down to 0.4 on sleep.

Regards Ian
 
cvloenen said:
I am suspecting I may be reading the multimeter wrongly. what I get on drain on the digital scale is 0.5 when meter set to 20Amps. I don't/can't get instrauctions for the meter as its old. However since the normal is around 0.005 I thinks this is what I'm getting. If I take out the clock fuse I get a drop of 0.1 on my meter which may be 0.01Amps does this sound about right to anyone? Bringing my meter reading down to 0.4 on sleep.

Regards Ian
Click to expand...

If the meter is set to 20 amps and the reading is 0.5 then that is 500Ma against the 30Ma that you should see. Go get yourself a meter you can rely on or you are chasing rainbows:rolleyes:
 
Did a check on my volvo to see what current draw is there when shut and came up with 0.04. So I was reading the meter correctly and it does appear that there is a massive draw from the battery on my Rangy (0.5A)
While doing a check on the Rangy I was moiving wires and shuggling relays and the reading dropped to 0.03. I have since taken out all fuses, relays and have failed to replicate the drop.
Atleast I know my meter is ok. I just need to find the fault. I've heard the alternator can cause the draw so I'll try checking that by disconecting the positive there and see what happens.

Any suggestions welcome.

Regards Ian
 
cvloenen said:
Did a check on my volvo to see what current draw is there when shut and came up with 0.04. So I was reading the meter correctly and it does appear that there is a massive draw from the battery on my Rangy (0.5A)
While doing a check on the Rangy I was moiving wires and shuggling relays and the reading dropped to 0.03. I have since taken out all fuses, relays and have failed to replicate the drop.
Atleast I know my meter is ok. I just need to find the fault. I've heard the alternator can cause the draw so I'll try checking that by disconecting the positive there and see what happens.

Any suggestions welcome.

Regards Ian
Click to expand...

The usual problem is the BECM not going to sleep, are you sure it was the RF receiver you disconnected and not the radio aerial amp?
Other possibles are headlamp wipers sticking, dodgy fusebox and as you have said, the alternator:)
 
could it have been one of the relay sticking and having burnt contacts as you said " While doing a check on the Rangy I was moiving wires and shuggling relays and the reading dropped to 0.03"
 
Hi all, I'm ging to have a look at the Rangy again tomorrow.

I have been conducting teste with bonnet open, is that a problem for this?

RF Reciever is the box immediately behind driver side rear seat under the parcel shelf side cowling against window. Disconnected a single blue wire if I remember corrcetly. Where is the radio amp to be sure?
 
cvloenen said:
Hi all, I'm ging to have a look at the Rangy again tomorrow.

I have been conducting teste with bonnet open, is that a problem for this?

RF Reciever is the box immediately behind driver side rear seat under the parcel shelf side cowling against window. Disconnected a single blue wire if I remember corrcetly. Where is the radio amp to be sure?
Click to expand...
Either the black or blue box next to it!!
 
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