Battery Draining

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charliezedster
Joined: Tue 13 Jul, 2010 11:31
Posts: 18

  Z3 roadster 2.8
Location: Nottingham

Battery Draining

Post by charliezedster »

My zed has been parked up for 4 weeks and when I went to start up last weekend the battery was dead. This was a new battery last Autumn! Does anyone know of anything that is still running on the car, when parked up ,which would discharge the battery over this short period?
swamper
Joined: Thu 13 May, 2010 17:14
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  M roadster S50
Location: Mossley

Post by swamper »

i had a a seat switch that was just slightly on and it drained the battery...might be worth a quick check.
the badness makes me do it...!

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Deano1712
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Post by Deano1712 »

Sounds like you have something draining it. Stick an ameter in circuit and see what its pulling. Any more than 40mA is too much. That level would drain the battery in 10 weeks so you are either pulling more current, the battery is u/s, or you started out with <50% charge.

What size battery did you fit? It should be 70AH (I think). If you have a smaller one that would explain it.
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charliezedster
Joined: Tue 13 Jul, 2010 11:31
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  Z3 roadster 2.8
Location: Nottingham

Battery Drained

Post by charliezedster »

swamper wrote:i had a a seat switch that was just slightly on and it drained the battery...might be worth a quick check.
Thanks, everything appears to be off, however have just noticed a flashing red light on the dash panel even though the car is unlocked, anyone know what this is?
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hornel Z3M
Joined: Sun 16 May, 2004 20:33
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Post by hornel Z3M »

Dont forget the cold weather will drain the battery and the alarm which is shows the flashing light on the dash all helps to drain the battery. get a ctek gharger they are great.
charliezedster
Joined: Tue 13 Jul, 2010 11:31
Posts: 18

  Z3 roadster 2.8
Location: Nottingham

Battery Drained

Post by charliezedster »

Deano1712 wrote:Sounds like you have something draining it. Stick an ameter in circuit and see what its pulling. Any more than 40mA is too much. That level would drain the battery in 10 weeks so you are either pulling more current, the battery is u/s, or you started out with <50% charge.

What size battery did you fit? It should be 70AH (I think). If you have a smaller one that would explain it.
Battery was new OEM from BMW dealer so should be right size!
charliezedster
Joined: Tue 13 Jul, 2010 11:31
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  Z3 roadster 2.8
Location: Nottingham

Post by charliezedster »

hornel Z3M wrote:Dont forget the cold weather will drain the battery and the alarm which is shows the flashing light on the dash all helps to drain the battery. get a ctek gharger they are great.
Does the alrm light flash even when unlocked?
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hornel Z3M
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Post by hornel Z3M »

Tes it should because if someone tried to lift it or bounce it the alarm is still activated and will sound
charliezedster
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  Z3 roadster 2.8
Location: Nottingham

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Post by charliezedster »

hornel Z3M wrote:Tes it should because if someone tried to lift it or bounce it the alarm is still activated and will sound
Thanks, will invest in a trickle charge or use my zed more often!
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Robert T
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  Z3 roadster 1.9
Location: Cheshire

Post by Robert T »

Which alarm do you have? The separate fob or the one with buttons on the key? With the former it is possible the siren has been switched off and if the alarm has triggered you might not hear it, but it has probably been flashing the indicators. With the later alarm this should not be the case, but you should try resetting the alarm to see if the LED stops flashing - if the remote doesn't work, putting the key in the ignition and turning to position II should.

Cheers R.
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henrycrun
Joined: Wed 18 Apr, 2007 19:48
Posts: 522

  Z3 roadster 1.9
Location: Ely

Re: Battery Draining

Post by henrycrun »

Holy thread resurrection.

Had a few problems recently with the ABS/DSC but now suffering flat battery.

Current drain is 0.4 Amp. Seat motors are off (fuses pulled)

Any ideas ?
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BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
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  Z3 roadster 1.9

Re: Battery Draining

Post by BladeRunner919 »

If you full the fuses one at a time, you can see which circuit is drawing current.
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
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Location: Daglan, France

Re: Battery Draining

Post by Mike Fishwick »

Typical drain is 30 mA, which over a four week period equals 20 ampere-hours - do the maths (.03 X 24 X 7 X4 = 20.16)

A lead acid battery in cold weather will hold about 50% of its capcity at 20 C, and your battery was probably not fully charged, so it is not surprising that after a month of neglect your battery has gone flat. Buy a battery charger, and use it when you do not use the car! Such gross neglect kills more batteries then anything else, whichis why it is specifically excluded from battery warranties.
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henrycrun
Joined: Wed 18 Apr, 2007 19:48
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  Z3 roadster 1.9
Location: Ely

Re: Battery Draining

Post by henrycrun »

Thanks.
I assume the quickest way to check all fuses & current drain is to run a long lead from the -ve battery terminal to the front of the car ?
Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
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Location: Daglan, France

Re: Battery Draining

Post by Mike Fishwick »

Long wire? Why?

To measure the normal drain (known as the quiescent current) fit an ammeter in place of the battery earth cable - this will tell you the rate of discharge.
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Robert T
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Re: Battery Draining

Post by Robert T »

Thinking about it, yes. The battery is in the boot and the fusebox is under the bonnet, so to save a lot of running about you want both to hand. You either need long leads on your multimeter, or test between chassis and battery earth. Best point to do this I would think is the jump start earth point on the right hand front suspension strut tower.

Cheers R.

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Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
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  Z3 roadster 2.8
Location: Daglan, France

Re: Battery Draining

Post by Mike Fishwick »

Yes, disconnect the battery earth cable, and use a long wire from the battery earth terminal to the meter, and the normal meter lead to the earth point under the bonnet is what you need, but before getting involved in pulling fuses, first try the basic test of measuring the discharge current, by connecting the meter between the battery negative terminal and earth. If it is in the 30 to 40 mA area, you do not need to pull any fuses, and must simply accept blame for the early demise of your battery!

My batttery is always on float charge whenever the car is at home, and my original battery was replaced after twelve years, as although it still started the engine, three of the cells were showing very low specific gravity readings, so were on the way out - another winter would have killed it. I also checked the cell levels every month or so, topping up with de-mineralised water - something which most people do not seem to think about. Lower cell levels mean a greater concentration of acid, and more sulphation of the plates, causing less capacity.
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sirius-c
Joined: Wed 12 Dec, 2012 22:24
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Re: Battery Draining

Post by sirius-c »

Do you chaps leave the battery connected to the Z3 when charging over winter or for extended periods of time... or do you disconnect and remove it to charge?
If left connected where do you attach the charger...directly to the battery or the terminals under the bonnet


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t-tony
Joined: Sun 21 Feb, 2010 23:17
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  Z3 roadster 2.0
Location: torksey lock

Re: Battery Draining

Post by t-tony »

Either re charge the battery when it goes flat or connect a trickle charger to the battery terminals direct. That's what I do. Also for Christmas last I got a starter/charger so if you need to start your car quickly you can.
"Knowledge and experience are not always the same"
t-tony
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Re: Battery Draining

Post by t-tony »

Either re charge the battery when it goes flat or connect a trickle charger to the battery terminals direct. That's what I do. Also for Christmas last I got a starter/charger so if you need to start your car quickly you can.
"Knowledge and experience are not always the same"
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Geoff H
Joined: Sat 08 Nov, 2003 12:03
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Re: Battery Draining

Post by Geoff H »

sirius-c wrote:Do you chaps leave the battery connected to the Z3 when charging over winter or for extended periods of time... or do you disconnect and remove it to charge?
If left connected where do you attach the charger...directly to the battery or the terminals under the bonnet
I connect direct to the battery. My trickle charger came with a lead which is fitted permanently to the battery, it has a plug on the loose end which sticks thru into the boot. The charger is fitted to wall in the garage, so I just have to open the boot and plug the two together and close the boot down to the plungers, there is enough room so the cable is not trapped. I leave it connected all the time when the car isn't used
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sirius-c
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Re: Battery Draining

Post by sirius-c »

Thanks for info :)
Designed or not designed, that is the question.
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RockyDave
Joined: Sun 22 Sep, 2013 07:18
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Re: Battery Draining

Post by RockyDave »

One of the most useful things I have bought to monitor battery "condition" is the "CTEK CTE-56382 Comfort Indicator with 8mm Eyelet Adaptors" (Amazon £6.78) I have this connected to the battery in the boot with the three LED indicator visible, green LED means battery is fine, red LED means it's time to plug in the trickle charger.
To trickle charge the car I use a CTEK MXS 5.0 charger that plugs straight into the cigarette lighter socket on the dash with this accessory (CTEK CTE-56263 CTEK Cigarette Lighter Connector Adaptor).
This has worked really well, keeping the battery fully charged, over the winter. :)

Hope this helps,
Dave.
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Alan W
Joined: Thu 20 Jun, 2013 10:56
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Re: Battery Draining

Post by Alan W »

Check that the boot interior light is off when the boot is shut, best way to do that is switch on video camera on your mobile phone and place it in boot and close the boot, wait a few seconds and then retrieve and watch the video. Something you need to rule out
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sirius-c
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Re: Battery Draining

Post by sirius-c »

Alan W wrote:Check that the boot interior light is off when the boot is shut, best way to do that is switch on video camera on your mobile phone and place it in boot and close the boot, wait a few seconds and then retrieve and watch the video. Something you need to rule out
That is a great tip. :cheers
If you could've seen me messing about squinting through the hairline gap as I closed the boot to check this you would've rolled your eyes :dunce:

I wish I had some common sense sometimes
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Mike Fishwick
Joined: Fri 19 Jun, 2009 10:27
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Location: Daglan, France

Re: Battery Draining

Post by Mike Fishwick »

In spite of the well-meaning rubbish about disconnecting the battery, and removing the filler plugs, unless you have a particularly brutal type of battery charger this is not necessary. All a modern automatic charger does when set to 'Auto' or 'Float Charge' is to simulate what happens when the alternator is in use - producing a stable 13.8 volts or so, current being limited by the state of charge, and the maximum current the charger is capable of providing. This will charge the battery to about 90% of its capacity, just below the point where 'gassing' takes place, so very little electrolyte will be lost.

Unless you have a zero-maintenance battery, it is however worth removing the filler plugs at least once a year to check the level in each cell, topping up if necessary with demineralised water - as used in steam irons etc.

I use the cigar lighter too, but remember that if the battery is flat, charging current will be limited by the series resistor built intothe lighter body to restrict current. For normal float charging it is fine, but the lighter-type plug can somethines be rather tempramental.

I always mean to fit a BMW/Hella power socket instead, which is a far better piece of work.
A Z3 is not just for Christmas - it's for life!
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