[Ermin335]

Hello Beamer community.

Some background before I even start with the issue that started happening with my car: Purchased a 2014 BMW 335i in 2017, never had issues. A couple months ago when I went to turn on my car, a message popped up on the display which said, "Battery Discharging While Stopped". I asked the mechanic that I have taken my car to since I have gotten it, and he said to come in. There weren't any faults that showed up so I figured that I just needed a new battery (keep in mind, I have never had it replaced). I went to the BMW dealership in my area, and purchased a new battery. Got it installed, and registered with the vehicle, and there were no issues for a few weeks...

I woke up one morning to head to work, and I noticed that when I put my hand on the handle, the door knobs barely went up, and then my alarm started BLASTING. I quickly tried to turn the alarm off by pressing every button on my key fob, but no luck. The alarm eventually stopped so I tried to turn on my car and absolutely nothing worked. My wipers started going for some random reason, my bluetooth turned on for 5 seconds and then turned off.

I have resorted to jumping my vehicle 2 times in the last week in order to get to work, and every morning I get the message saying that there was a battery discharge.

Do you guys have any ideas on how I can figure out what is draining this brand new battery? I am at a loss.

[Ermin335]

EDIT: I had my mechanic look at the car last night, and there was under voltage detected in the roof function center. I'm assuming that is the sun roof in the car?

[Billfitz]

That probably refers to the controls over and in the mirror. The symptoms are those of parasitic power drain. Search it.

[Fredo]

My 2012 F30 335i started to have the same issue around 3 years ago. In my case, it's very sporadic. It happened in October 2023 and everything was fine until this weekend. The battery has been dead two days in a row (Saturday and Sunday).

I already took the car to 2 different shops and they could not find an explanation. They asked me to bring the car when the issue is happening. I plan to do that sometime soon since the problem is back.

Luckily I have an extra car that I can drive for now.

[Ermin335]

Originally Posted by Billfitz

That probably refers to the controls over and in the mirror. The symptoms are those of parasitic power drain. Search it.

Ahhh got it, thanks. I was thinking about switiching out the FEM module, but don’t want to spend the money yet since the issue hasn’t been pinpointed

[Ermin335]

Originally Posted by Fredo

I already took the car to 2 different shops and they could not find an explanation. They asked me to bring the car when the issue is happening.

Interesting. I noticed that whatever is draining my battery, seems to only happen over night.

Hopefully we can both find out what’s going on with our cars

[Billfitz]

It happens overnight because something that's supposed to shut off when the engine isn't running isn't. The shops can't find it because it's a long and complicated process to track it down.

[Orion4]

More than likely parasitic discharge. I had a similar issue and traced to the water pump electronic module (on top of the pump assembly). Pump was continuing to run after the normal 5 min period when the car electronics are suppose to go to "sleep". I could see the drain continuing after that time via my multi-meter and finally traced it to the pump (could hear it still running).

[Fredo]

Originally Posted by Ermin335

Interesting. I noticed that whatever is draining my battery, seems to only happen over night.

This is what happened to me on Friday:

1 ) At 8 AM, the warning "battery discharging while stopped" showed but car still started fine. Drove 10 miles to work.

2 ) At 5 PM, the car started fine. I remember the same warning showed again. Drove 10 miles back home.

3 ) At 6 PM, the battery was totally dead. I needed to use my jump pack.

[Ermin335]

Originally Posted by Orion4

More than likely parasitic discharge. I had a similar issue and traced to the water pump electronic module (on top of the pump assembly). Pump was continuing to run after the normal 5 min period when the car electronics are suppose to go to "sleep". I could see the drain continuing after that time via my multi-meter and finally traced it to the pump (could hear it still running).

Leaning towards this. I will be going to a different mechanic tomorrow and will hopefully find out

[Ermin335]

Originally Posted by Fredo

This is what happened to me on Friday:

1 ) At 8 AM, the warning "battery discharging while stopped" showed but car still started fine. Drove 10 miles to work.

2 ) At 5 PM, the car started fine. I remember the same warning showed again. Drove 10 miles back home.

3 ) At 6 PM, the battery was totally dead. I needed to use my jump pack.

Could possibly be your alternator? If you drove 10 miles back home, I’d assume your battery would recharge to somewhat of a decent level and not completely die an hour later.

Not a mechanic so don’t take my word for it

[Billfitz]

A must have. When the engine isn't running it shows the battery state of charge. When it is running it shows the alternator output. Mine is always plugged in to my console socket.
https://www.amazon.com/Battery-Charg...%2C102&sr=1-27

[Fredo]

Originally Posted by Billfitz

A must have. When the engine isn't running it shows the battery state of charge. When it is running it shows the alternator output. Mine is always plugged in to my console socket.
https://www.amazon.com/Battery-Charg...%2C102&sr=1-27

I got the battery monitor thanks to your recommendation in another thread. I didn't know you can leave it plugged all the time. I assumed that could discharge the battery on the long term.

I compared the results when the engine is not running between my 335i (which has the issue) and my wife's 2011 X3:

335i = 10.20 volts, red indicator

X3 = 12.06 volts, yellow indicator

[Billfitz]

It would only discharge the battery if the power to the outlet remained on with the engine off. It does stay on for about five minutes after the car has been locked, ten minutes or so if the engine is shut off but the car isn't locked.

10.2 volts indicates the battery is at only 10% charge. I'd be surprised if the car would start. If you fully charge the battery after a long drive it should show at least 12.5v when you turn the engine off. If it drops to 10.2v either something is draining the battery or the battery is toast. You can check that by fully charging the battery and then disconnecting the battery negative terminal, so nothing can drain it. If it's down the next morning you know it's the battery. If not it's something else.

12.06 volts is 60% charge, which is probably OK, but you don't want to see it going much lower.

[Fredo]

Originally Posted by Billfitz

It would only discharge the battery if the power to the outlet remained on with the engine off. It does stay on for about five minutes after the car has been locked, ten minutes or so if the engine is shut off but the car isn't locked.

10.2 volts indicates the battery is at only 10% charge. I'd be surprised if the car would start. If you fully charge the battery after a long drive it should show at least 12.5v when you turn the engine off. If it drops to 10.2v either something is draining the battery or the battery is toast. You can check that by fully charging the battery and then disconnecting the battery negative terminal, so nothing can drain it. If it's down the next morning you know it's the battery. If not it's something else.

12.06 volts is 60% charge, which is probably OK, but you don't want to see it going much lower.

I appreciate the detailed explanation, thank you.

[Fredo]

Two weeks ago, my battery was dead on 2 consecutive days. I stopped driving the car at that point. I checked the battery last week and it had only 8 volts. I assumed my jump pack was not going to work so I bought a CTEK MXS 5.0 Battery Charger & Maintainer on Amazon.

I connected the CTEK on Friday night and the car started fine on Saturday morning. It appears to be ok for now. My plan was to bring the car to the shop on Monday morning for troubleshooting, but now that makes no sense because the issue is gone.

I will continue to monitor the battery while the car is parked in the garage.

[richardodn]

Last winter I had an issue with an E83 X3. In my case, if I didn't start it for a few days it would be weak starting. A week and it would no longer start. I was bringing it into the dealer for other reasons, so I thought I'd have them check the electrical system. They had a device that they plugged into the car that monitored all kinds of things over time. In my case, the combox was waking up every 20 minutes with high current draw for a short time and then would go back to sleep. This was even when the car was supposedly in it's lowest power state. $250 flat charge at my dealer. I never would have found that and I'm a decent diagnostician.

[Ermin335]

Originally Posted by richardodn

Last winter I had an issue with an E83 X3. In my case, if I didn't start it for a few days it would be weak starting. A week and it would no longer start. I was bringing it into the dealer for other reasons, so I thought I'd have them check the electrical system. They had a device that they plugged into the car that monitored all kinds of things over time. In my case, the combox was waking up every 20 minutes with high current draw for a short time and then would go back to sleep. This was even when the car was supposedly in it's lowest power state. $250 flat charge at my dealer. I never would have found that and I'm a decent diagnostician.

Interesting. I took my car to a specialist in my area, and unfortunately they weren’t able to find anything that could be drawing power. However, the battery problems have suddenly stopped, and my car is working completely fine.

I might follow in your footsteps and take my car to the local dealer to see if they could find the issue.

[RezNaz]

Originally Posted by Orion4

More than likely parasitic discharge. I had a similar issue and traced to the water pump electronic module (on top of the pump assembly). Pump was continuing to run after the normal 5 min period when the car electronics are suppose to go to "sleep". I could see the drain continuing after that time via my multi-meter and finally traced it to the pump (could hear it still running).

My friend, I have the same problem as yours right now, after turning off and closing the doors, the water pump works and turns off and I can hear it. I remove the negative clamp every night so that my battery does not run out. Did you replace the water pump and the problem was solved? I'm not sure if it's the water pump, could it be the sensor or something else? Please share your experience with us.

[Orion4]

In my case, it was the electronic module that is part of the water pump assembly. It was running the pump long after the 5 min window after which the car "goes to sleep". I could watch the discharge on my meter as I was listening to the pump continue to run.

[RezNaz]

Originally Posted by Orion4

In my case, it was the electronic module that is part of the water pump assembly. It was running the pump long after the 5 min window after which the car "goes to sleep". I could watch the discharge on my meter as I was listening to the pump continue to run.

I have exactly the same problem as you. I will take the car to replace the water pump and thermostat today, and I will share the result with you. I hope that the problem will be solved with these 2 parts!

Thank you for the advice.

[Billfitz]

Before you pay to have the water pump replaced see if you're covered by the water pump recall. https://www.caranddriver.com/news/a6...e-risk-recall/