Battery keeps going flat

AnotherZ4Owner · 12-08-2023, 04:53 PM

My e89 z4 battery is having electrical issues and keeps going flat. Auto mechanics are weeks out here, so looking for online answers (which seem to be more professional than mechanics anyway).
I had the battery replaced with a HD battery. It lasted about a week and went flat.
I had someone out to test it and they said it was parasitic draw but they couldn't test it. I booked an auto electrician (2 weeks wait) and they cancelled today. So I had roadside assist out and they charged the battery again. He said it was 100% flat. I took it for a drive, came back, turned it off and it instantly went flat.
The park brake won't even turn on and has a warning coming up.
The roof down button is flashing. Could that be a problem with the roof module?
BMW has a lot of issues with the main battery cable corroding as well.
Has anyone had this issue?

DavesZed · 12-09-2023, 05:14 AM

No good guessing what's wrong, you need a good code reader and see what comes up. This'll be you first good starting point, from there you can then research what to do (hopefully).
I'm sure some would come on here suggesting this and suggesting that, but that'll just have you chasing ghosts. Having battery issues will always bring up a number of faults, this is due to lack of power to all the numourous modules within the car, so don't go chasing stuff until you've got exact answers.
Phone apps like Carly and Bimmercode will work, but you normally need their own specific OBD dongles for them to work and a subscription. There are a number of stand-alone code reders that have a built-in cable and OBD connector as well. Then there's software for your laptop like BMW Tools package that includes an program called INPA which reads your codes, all you need then is a USB to OBD cable as the software is free (although some will sell thei as well).

B21 · 12-09-2023, 06:12 AM

As David said without a decent code reader you’re not going anywhere…

Once the battery has been,n flattened a couple of times you’ll need a new AGM battery..

Often the cause of the parasitic draw is a Bluetooth system that won’t shut down or comfort access …

The code reader will show what’s causing the isdue..probably

KennyP · 12-09-2023, 07:16 AM

Does alternator even charge the battery when engine is running?
For me its wierd when you go for a drive (battery should be charging during that), then turn it off and instantly the battery is dead... a parasidic draw wouldnt kill the battery instantly and would take time...

I had an alternator go out on me... but i got a message saying battery not charging or something like that on idrive when i turned it on. So i parked it, checked the voltage on the battery while engine was on and it surely wasnt charging it (voltage was lower than it should). So next went and ordered a new alternator.. replaced it and problem was fixed...

Also how was your battery replaced? What is HD battery? A battery with more amphours? Was new battery coded to the car?
Even if you replace old battery with a new one and its the same type and capacity you still have to tell the battery management system that a new battery was installed so it would reset all the charging adaptations. Otherwise it would continue to charge it as if it was the old worn out battery and shorten the life of the newly installed battery
and if you change the size and/or type of the battery its even more crucial to tell the system what type and size the battery is that its dealing with...

Defective battery maybe?
Why did you replace the battery? Did it have same issues with the old battery?

javis20 · 12-09-2023, 09:36 AM

Having an E89, I would avoid both Carly and BimmerLink. At some point in the future you will have convertible top issues. In the event of these failures, you can't pop the trunk/boot with the keyfob or trunk release button. You will need to get into the trunk to access the hydraulics, CTM module and/or use special tool to get top into service position. BimmerGeeks ProTool, INPA and ISTA can over ride faults to open trunk.

Otherwise you will be one of the many posting here because their top is stuck/broken and they can't get into the trunk to facilitate repairs.

javis20 · 12-11-2023, 07:42 AM

Could possibly be one of the convertible top salmon relays stuck closed resulting in a burned out hydraulic pump. Pump would be running continuously even with the car off. Check the relays located next to the battery on the pump housing. Could be why you have both a flat battery and a red convertible top light. Robbie advises replacing them around 5 years.

Also, check alternator voltage with car running. Should be approx. 14vdc.

12-08-2023, 04:53 PM	#1
AnotherZ4Owner Registered 0 Rep 2 Posts Drives: e89 z4 Join Date: Dec 2023 Location: Australia iTrader: (0)	Battery keeps going flat - roof module? My e89 z4 battery is having electrical issues and keeps going flat. Auto mechanics are weeks out here, so looking for online answers (which seem to be more professional than mechanics anyway). I had the battery replaced with a HD battery. It lasted about a week and went flat. I had someone out to test it and they said it was parasitic draw but they couldn't test it. I booked an auto electrician (2 weeks wait) and they cancelled today. So I had roadside assist out and they charged the battery again. He said it was 100% flat. I took it for a drive, came back, turned it off and it instantly went flat. The park brake won't even turn on and has a warning coming up. The roof down button is flashing. Could that be a problem with the roof module? BMW has a lot of issues with the main battery cable corroding as well. Has anyone had this issue?
	Appreciate 0 Tweet Quote

12-09-2023, 05:14 AM	#2
DavesZed Lieutenant 151 Rep 511 Posts Drives: BMW E89 23i, 2011 Join Date: Nov 2015 Location: Grantham, UK iTrader: (0)	No good guessing what's wrong, you need a good code reader and see what comes up. This'll be you first good starting point, from there you can then research what to do (hopefully). I'm sure some would come on here suggesting this and suggesting that, but that'll just have you chasing ghosts. Having battery issues will always bring up a number of faults, this is due to lack of power to all the numourous modules within the car, so don't go chasing stuff until you've got exact answers. Phone apps like Carly and Bimmercode will work, but you normally need their own specific OBD dongles for them to work and a subscription. There are a number of stand-alone code reders that have a built-in cable and OBD connector as well. Then there's software for your laptop like BMW Tools package that includes an program called INPA which reads your codes, all you need then is a USB to OBD cable as the software is free (although some will sell thei as well). __________________ Dave 2011, E89 23i, Grey with Red leather.... relatively basic (getting less and less basic with every new retrofit)! My Z4 E89 YouTube channel... https://www.youtube.com/channel/UCtt...0vHFUQnoEvKB2Q
	Appreciate 0 Quote

12-09-2023, 06:12 AM	#3
B21 Captain 153 Rep 611 Posts Drives: E89 Atacama Yellow 35is Join Date: May 2022 Location: Scotland..God’s own country iTrader: (0)	As David said without a decent code reader you’re not going anywhere… Once the battery has been,n flattened a couple of times you’ll need a new AGM battery.. Often the cause of the parasitic draw is a Bluetooth system that won’t shut down or comfort access … The code reader will show what’s causing the isdue..probably __________________ Much modified 2011 Atacama Yellow 35is…previously a much modified 2012 Atacama Yellow 20i MSport Change history here… https://www.dropbox.com/s/8h1vabklgz...0List.pdf?dl=0 Build thread here… https://z4-forum.com/forum/viewtopic.php?t=131886
	Appreciate 0 Quote

12-09-2023, 07:16 AM	#4
KennyP Lieutenant 147 Rep 463 Posts Drives: 2009 Havana E89 Z4 Sdrive35i Join Date: Apr 2016 Location: Estonia iTrader: (0)	Does alternator even charge the battery when engine is running? For me its wierd when you go for a drive (battery should be charging during that), then turn it off and instantly the battery is dead... a parasidic draw wouldnt kill the battery instantly and would take time... I had an alternator go out on me... but i got a message saying battery not charging or something like that on idrive when i turned it on. So i parked it, checked the voltage on the battery while engine was on and it surely wasnt charging it (voltage was lower than it should). So next went and ordered a new alternator.. replaced it and problem was fixed... Also how was your battery replaced? What is HD battery? A battery with more amphours? Was new battery coded to the car? Even if you replace old battery with a new one and its the same type and capacity you still have to tell the battery management system that a new battery was installed so it would reset all the charging adaptations. Otherwise it would continue to charge it as if it was the old worn out battery and shorten the life of the newly installed battery and if you change the size and/or type of the battery its even more crucial to tell the system what type and size the battery is that its dealing with... Defective battery maybe? Why did you replace the battery? Did it have same issues with the old battery? __________________ 2009 35i DCT Havana brown with ivory white interior. Mods: Cobb stage 1+FMIC, Wagner EVO1 FMIC, BMS DCI, KW V3 suspension, M3 front control arms, Hardrace RTAB, Michelin Pilot Sport 4S tires. Last edited by KennyP; 12-09-2023 at 07:26 AM..
	Appreciate 0 Quote

12-09-2023, 09:36 AM	#5
javis20 Private 13 Rep 76 Posts Drives: 2011 Z4 3.0i Silver Join Date: Aug 2018 Location: Central PA iTrader: (0)	Having an E89, I would avoid both Carly and BimmerLink. At some point in the future you will have convertible top issues. In the event of these failures, you can't pop the trunk/boot with the keyfob or trunk release button. You will need to get into the trunk to access the hydraulics, CTM module and/or use special tool to get top into service position. BimmerGeeks ProTool, INPA and ISTA can over ride faults to open trunk. Otherwise you will be one of the many posting here because their top is stuck/broken and they can't get into the trunk to facilitate repairs.
	Appreciate 0 Quote

12-11-2023, 07:42 AM	#6
javis20 Private 13 Rep 76 Posts Drives: 2011 Z4 3.0i Silver Join Date: Aug 2018 Location: Central PA iTrader: (0)	Could possibly be one of the convertible top salmon relays stuck closed resulting in a burned out hydraulic pump. Pump would be running continuously even with the car off. Check the relays located next to the battery on the pump housing. Could be why you have both a flat battery and a red convertible top light. Robbie advises replacing them around 5 years. Also, check alternator voltage with car running. Should be approx. 14vdc.
	Appreciate 0 Quote