Battery drain and help with numbers
Discussion
After 4/5 days of not using my 2005 cooper S I found it had a flat battery. The following day I went to get the battery out to charge but the car was even more dead. Had to unlock it with the key and pull the manual boot release.
The battery is less than 6 months old so I think it's a good one. After a quick charge at home it was reading 12.3v. With the car on idle it reads 14.4V.
Just tested the battery drain with my multimeter. With the car locked and interior lights on it's reading 2.25. After 10-15 seconds the lights go out and reading falls to 0.61. 5 mins later it falls to 0.30. Just left it 30-40 mins and now the reading has fell to 0.18.
Is this enough of a drain to cause the battery to go flat? Or was I stupid and left something on by accident?
The battery is less than 6 months old so I think it's a good one. After a quick charge at home it was reading 12.3v. With the car on idle it reads 14.4V.
Just tested the battery drain with my multimeter. With the car locked and interior lights on it's reading 2.25. After 10-15 seconds the lights go out and reading falls to 0.61. 5 mins later it falls to 0.30. Just left it 30-40 mins and now the reading has fell to 0.18.
Is this enough of a drain to cause the battery to go flat? Or was I stupid and left something on by accident?
Any ideas what the drain should be?
The car is quite a low spec 2005 cooper S. No Nav, no spots, standard stereo with cd changer in the boot. Gonna have a go at pulling fuses to see what effect it has on my reading.
It's not the first time i found it with a flat battery. The first time I put it down to an old battery (it looked like the original Bmw unit) and it never charged to over 11V. Replaced that for a New Bosch. Second time I left the car standing over the christmas/new year period. I wasn't happy come new year but I thought the bad weather, heavy frost and some snow played a part. Now it's mild I have began to cycle to work so the car gets left at home 5/6 days a week. You would think a fresh battery would start the damn thing after a week of rest. It's not a bloody iPhone!
It could possibly be that something was left on, however I'm 90% sure there wasn't. I only have a very basic understanding of electrics so any further help would be much appreciated.
The car is quite a low spec 2005 cooper S. No Nav, no spots, standard stereo with cd changer in the boot. Gonna have a go at pulling fuses to see what effect it has on my reading.
It's not the first time i found it with a flat battery. The first time I put it down to an old battery (it looked like the original Bmw unit) and it never charged to over 11V. Replaced that for a New Bosch. Second time I left the car standing over the christmas/new year period. I wasn't happy come new year but I thought the bad weather, heavy frost and some snow played a part. Now it's mild I have began to cycle to work so the car gets left at home 5/6 days a week. You would think a fresh battery would start the damn thing after a week of rest. It's not a bloody iPhone!
It could possibly be that something was left on, however I'm 90% sure there wasn't. I only have a very basic understanding of electrics so any further help would be much appreciated.
0.18 Amps current draw is far too high, that is the equivalent of 2.16 Watts
Have you checked the glove box, boot light etc
Another problem could be an incorrect or faulty relay
Take a look at the below link as it will help you
You could start off by pulling out the fuses 1 by 1 to see if it cures the drain and points to the fault
http://www.diagnosticnews.com/parasitic-battery-dr...
Have you checked the glove box, boot light etc
Another problem could be an incorrect or faulty relay
Take a look at the below link as it will help you
You could start off by pulling out the fuses 1 by 1 to see if it cures the drain and points to the fault
http://www.diagnosticnews.com/parasitic-battery-dr...
That's great help, thanks.
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
irob said:
That's great help, thanks.
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
Yes, presuming you are using a 10 amp range. A lower current range (e.g. 200mA) would give you better precision, but you need to be careful that you don't blow the meters internal fuse.I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
50mA is right at the upper end of what I'd consider acceptable.
Edited by Mr2Mike on Tuesday 19th May 14:32
irob said:
That's great help, thanks.
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
Yes and NoI understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
Yes. So a reading of 0.18 on my multimeter LCD is 180 Miliamps
No. Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05
No one has quoted you the correct current draw for you model of car, you need to get hold of the dealer information, phone a dealer and ask what the figure should be and also check how long the car needs to be stood with everything switched off before it can be checked correctly
All makes and models are different
That's great help, thanks.
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
I understand the theory of battery draw/parasitic drain but don't quite understand the numbers/scale of what I'm trying to achieve. I'm more of a spanner and hammer kind of home mechanic.
So a reading of 0.18 on my multimeter LCD is 180 Miliamps?
Ideally I need to get that down to 35-50 Milliamps. So it needs to show 0.03-0.05?
Don't pull fuses either to check for drain. You will likely wake up control modals when refitting the fuse. Watch the video here and look for Battery Drain - Parasitic Draw and skip to about 4:45 this shows you how to measure drain without triggering modals. Sorry if this has been covered above.
Matt Seabrook said:
Don't pull fuses either to check for drain. You will likely wake up control modals when refitting the fuse. Watch the video here and look for Battery Drain - Parasitic Draw and skip to about 4:45 this shows you how to measure drain without triggering modals. Sorry if this has been covered above.
Do Pull fuses but dont put them back in until you have identified the problem circuitIf you do pull a fuse and immediately put it back in, you will need to allow time before carrying on with the testing
Even pulling fuses can wake up other modals. Sorry pulling fuses is the old way of doing this and can give inaccurate information. Also if you pull fuses and don't replace them if a system does wake up but the thing it was powering needed a fuse you have already pulled to work you may not see what you are looking for. I know I have been there 
Here is a chart for the voltage drop method Click
Here is a chart for the voltage drop method Click
Edited by Matt Seabrook on Thursday 21st May 09:01
Just bear in mind that mini and maxi fuses will have a different voltage drop for the same fuse size. Edited by Matt Seabrook on Thursday 21st May 09:02
guzzler4 said:
Matt Seabrook said:
Even pulling fuses can wake up other modals. Sorry pulling fuses is the old way of doing this and can give inaccurate information. Also if you pull fuses and don't replace them if a system does wake up but the thing it was powering needed a fuse you have already pulled to work you may not see what you are looking for. I know I have been there
Here is a chart for the voltage drop method Click
IMO Penelope Stopit gives good advice, perhaps you should stick to changing tyres (Only Joking)Here is a chart for the voltage drop method Click
Edited by Matt Seabrook on Thursday 21st May 09:01
Just bear in mind that mini and maxi fuses will have a different voltage drop for the same fuse size. Edited by Matt Seabrook on Thursday 21st May 09:02
As for sticking to just fitting tyres. That would be lovely if there was enough money to be made in just fitting tyres round here. So we have to cover quite a bit more than just tyres. I have had an interest in electronics since I was a boy. I passed my Radio Ham licence when I was 14 in 1982. This was the youngest age you could take the exam at the time (things may have changed). This exam was prominently an electronic exam and this is where my love of electronics started. I still do training and regularly go on training courses for work. Even though my understanding of electronics is better than some I started a program of Bosch Diagnostic Technician courses about three years ago. I started at the beginning as even though the starter courses are a little basic if you start from where I did, I did not think it wise to jump in half way through. As you will see below the VSE1 course is Essential Test Procedures ie electronics and how to test vehicle electrical circuits. If you want I can put up some of my other qualifications but I chose not to as its going to look like I'm showing off. So you can see I have something to back up my statements. I wish nobody an ill will on this matter but just trying to help someone (the OP) out that may go down a lengthy route without getting the results they deserve for the input they have made.
Oh by the way sorry if you have a bit of a thing for Penelope Stopit I am not one to stand in the way of man love if that's your thing assuming Penelope Stopit is a man of course? Each to there own
(Just joking) Matt Seabrook said:
Even pulling fuses can wake up other modals. Sorry pulling fuses is the old way of doing this and can give inaccurate information. Also if you pull fuses and don't replace them if a system does wake up but the thing it was powering needed a fuse you have already pulled to work you may not see what you are looking for. I know I have been there
Here is a chart for the voltage drop method Click
Every day is a learning day.... Thank you for that MattHere is a chart for the voltage drop method Click
Edited by Matt Seabrook on Thursday 21st May 09:01
Just bear in mind that mini and maxi fuses will have a different voltage drop for the same fuse size. Edited by Matt Seabrook on Thursday 21st May 09:02
irob said:
Yep, Classic re-post.
I'm getting my head around it now. Will attempt to contact someone regards the acceptable battery drain. For now I will begin to pull fuses one by one to narrow down the draw. Thanks for the help.
You might find it easier using a fuse plug in meter. This allows you to easily measure the current draw on each circuit. Far easier in my experience.I'm getting my head around it now. Will attempt to contact someone regards the acceptable battery drain. For now I will begin to pull fuses one by one to narrow down the draw. Thanks for the help.
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