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.
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?
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?
Firstly I would like to say thanks for the help. I would love to say I have found the route of my problem but I have not. I am still draining 180ma when the car is locked down. However I have been using it every day for the past week or so and have yet to suffer a fully drained battery.
I began by looking at the basics. All interior lights work as they should. I replaced the cheapo LED puddle lights found in the bottom of the doors with regular items. A broken earth strap from the bonnet to bulkhead was replaced with a new one. All other electrical items work apart from my headlamp washers. These have never worked since I have owned the car (could it be a problem?)
I measured the current across all fuses within the engine bay and interior fuse boxes. The only two fuses that measured a reading was the fuse for interior lights (but only when they were on) and fuse number F4 that if I understand the diagrams correctly is labelled ‘Constant Power’ This fluctuated between 1-2mv
Mini, in their wisdom seem to have 2 different fuse boxes for pre and post face lift cars. But the only difference being fuse F4! If anyone cares to google image the differences my icon is a circle with a few lines though it, the other looks like an open book.
Anyway, I then decided to go ‘old school’ by pulling fuses one by one but nothing I did seemed to reduce my reading of 180ma.
One thing I havn’t checked yet are the large fuses that sit underneath the engine bay fuse box. To get to them you have to disconnect the main battery lead and remove the top half of the fuse box but by doing so they don’t get any power so I have no idea how to test them?
Seems like the mini forums are full of battery drain issues. Main culprits are HK upgraded stereos and iPod connectors, which I have not got. Or power steering pumps/fans, but having tested and pulled these fuses I’m not so sure.
Still more digging to do.
I began by looking at the basics. All interior lights work as they should. I replaced the cheapo LED puddle lights found in the bottom of the doors with regular items. A broken earth strap from the bonnet to bulkhead was replaced with a new one. All other electrical items work apart from my headlamp washers. These have never worked since I have owned the car (could it be a problem?)
I measured the current across all fuses within the engine bay and interior fuse boxes. The only two fuses that measured a reading was the fuse for interior lights (but only when they were on) and fuse number F4 that if I understand the diagrams correctly is labelled ‘Constant Power’ This fluctuated between 1-2mv
Mini, in their wisdom seem to have 2 different fuse boxes for pre and post face lift cars. But the only difference being fuse F4! If anyone cares to google image the differences my icon is a circle with a few lines though it, the other looks like an open book.
Anyway, I then decided to go ‘old school’ by pulling fuses one by one but nothing I did seemed to reduce my reading of 180ma.
One thing I havn’t checked yet are the large fuses that sit underneath the engine bay fuse box. To get to them you have to disconnect the main battery lead and remove the top half of the fuse box but by doing so they don’t get any power so I have no idea how to test them?
Seems like the mini forums are full of battery drain issues. Main culprits are HK upgraded stereos and iPod connectors, which I have not got. Or power steering pumps/fans, but having tested and pulled these fuses I’m not so sure.
Still more digging to do.
Yep, Google does wonders for paranoia!
Just want to add that my car does have manual Air Con and I have no idea what Diodes are. Could somebody more clever than me talk me though how I could check individual components?
I am going to have another investigate over the weekend. I feel like I may have been doing something wrong and chasing my tail last time.
Just want to add that my car does have manual Air Con and I have no idea what Diodes are. Could somebody more clever than me talk me though how I could check individual components?
I am going to have another investigate over the weekend. I feel like I may have been doing something wrong and chasing my tail last time.
Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff