porksoda

I noticed something odd and most of it is probably by design but i am not sure if all is. I had my BEM active since october 2017 and i only noticed things were off when my comfort key stopped working and i started to search. I finally got vcds and scanned the car and i confirmed battery was out so i got a new battery and i have been noticing many differences - it maybe a placebo effect but wanted to get an opinion here from people with experience.

After bem code was removed and new battery intalled i noticed the car's mmi screen came out quicker than before and the mirrors were folding in and out faster. The thing that i am more surprised or concerned about is that car seems responsive and tends to feel zippier and either i had consequitive bad gas for a while but my mileage went up from doing about 500km per tank to about 575-600km per tank.

If the bem does slow down a lot of systems in terms of power consumption then why would things still be a bit slower while the car had started and power was being delivered via the alternator?

ByByBMW

BEM??

RamblingMan

I wondered too so I asked my friend Google told me. Battery Energy Management

Description link

KevinGary

DanfZX14

Porksoda - I can't answer any of your questions but when I ran a vcds scan I saw my BEM had kicked in too. When it is cold, I'd say below 35 degrees I lose the comfort key function. When it warms back up outside it works again. Had this happen last winter too. This year when it is cold the car has an additional ailment. When the car has been parked it does not remember the song the music player was up to and reverts back to whatever was playing last time it was warm out. This happens with CDs and the SD cards. Once it warms up outside all is fine again. This actually bothers me more than the comfort key not working but not enough to make me buy a new battery. Not yet anyways!

porksoda

@ByByBMW, @RamblingMan, and @KevinGary : Sorry guys, yes the BEM is the battery energy management system and it starts to cut power to various systems to conserve power when it goes below i think 11V. Basically if it kicks in, once you put in a new battery you should reset the BEM by entering a new SN for the battery.

@DanfZX14 : Same thing happened to me, i finally bought the vcds cable and say it was activated last year so i did replace the battery. What my concern was that car felt a lot better after battery changing, which i am not sure was by design or not. It would be a good idea to keep on top of battery if it is by design and you are losing some power and mileage as well - unless this was all in my head but i have had 3 gas fills and mileage had gone down considerably and as soon as i changed the battery bam it came right back up.

Lesson learnt for me is to always lock/arm the car in my garage, which i have not been doing at all!

RamblingMan

@porksoda, why lock the car in the garage?
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newmoon

I think when the battery is weak, the alternator has to work harder to charge it, so this would place more load on your engine and affect your fuel economy. This may also decrease the voltage available for all the other electrical systems.

newmoon

I lock it in my garage to ensure that all the systems shut down and don't wake up until I unlock it.

I have a BMW that does a similar thing. The dash and radio stay on for around 5 minutes after you shut off the engine unless you lock the car. Then they turn off immediately.

hotlips

Question: I always lock it when I pull in to fold the mirrors in, then I unlock it by the handle so I can put in/take thinks out until I am ready to leave again. Could be couple of days, at times. Regarding the system shut down - once locked are all systems shut down and stay down even if unlocked as I do?