I this is a long shot……………

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   but, is anyone here familiar with BMW’s? Son has a 2015 335i, when the weather turns cooler(under 50 deg F., the battery drains dead. Several battery swaps over the years, has not solved the issue, numerous trip to the stealership temporarily fixes the issue.  Last week when I was at his place it happened again, cool day, jump started the car, did his route for the day, came home, shut it off, couple hours later, battery dead as a door nail. Hooked up the charger, after a few minutes, the electric water pump turned on. I know the electric water pumps on these cars are problematic, has anyone conquered this issue. I know BMW’s are an electrical nightmare. Any help/suggestions, or some tanerite would be greatly appreciated. 

Edited by Lars(wi) - 2 hours 12 minutes ago at 10:46am

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Lars(wi) Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 14 Sep 2009 Location: Permian Basin Points: 8202	Post Options Post Reply Quote Lars(wi) Report Post Thanks(0) Quote Reply Topic: I this is a long shot…………… Posted: 2 hours 14 minutes ago at 10:44am
	but, is anyone here familiar with BMW’s? Son has a 2015 335i, when the weather turns cooler(under 50 deg F., the battery drains dead. Several battery swaps over the years, has not solved the issue, numerous trip to the stealership temporarily fixes the issue. Last week when I was at his place it happened again, cool day, jump started the car, did his route for the day, came home, shut it off, couple hours later, battery dead as a door nail. Hooked up the charger, after a few minutes, the electric water pump turned on. I know the electric water pumps on these cars are problematic, has anyone conquered this issue. I know BMW’s are an electrical nightmare. Any help/suggestions, or some tanerite would be greatly appreciated. Edited by Lars(wi) - 2 hours 12 minutes ago at 10:46am
	I tried to follow the science, but it was not there. I then followed the money, and that’s where I found the science.

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jaybmiller Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Greensville,Ont Points: 24818	Post Options Post Reply Quote jaybmiller Report Post Thanks(0) Quote Reply Posted: 1 hour 21 minutes ago at 11:37am
	no ,but it sounds like 'something' is turning on,draining the battery when <50*F. Maybe a seat heater,windshield heater or some other 'hightech' item ?? I'd put an ammeter between battery and 'the rest of the car' to see how much current is being drawn. Any lights on ( under the hood ?). Newer cars have 'CANbus' ballast resistors and they WILL kill a battery. Maybe the alternator is 'kinda' bad ? If ammeter say power is being used, start pulling fuses, one at a time, to locate WHICH circuit it is. Please report back with any new information !
	3 D-14s,A-C forklift, B-112 Kubota BX23S lil' TOOT( The Other Orange Tractor) Never burn your bridges, unless you can walk on water

AC7060IL Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 19 Aug 2012 Location: central IL Points: 3592	Post Options Post Reply Quote AC7060IL Report Post Thanks(0) Quote Reply Posted: 55 minutes ago at 12:03pm
	Not familiar with particular model. Google it? Search yr model issues & watch internet light up about issues. Good luck. Below is a link of my find from ; “2015 335i battery issues” search Could be it has “on demand” alternator charging?? If so, it’s battery’s ground terminal sensor may be defective? A temp fix ~ delete that sensor for a direct ground. That will produce a constant charge alternator to assist the moment. Get new sensor for long term fix. https://www.reddit.com/r/BmwTech/comments/11x4enb/2015_bmw_335i_battery_discharging_while_stopped_i/ Edited by AC7060IL - 39 minutes ago at 12:19pm