[brlawyer]

This may have been asked already, but I will try anyway - due to some stupid, neverending road works in front of my place, it is currently very difficult for me to exit my house garage with the 840d.

So my question is: how long can I keep it there (without running the engine) before the battery runs out?

[Broccoli-mobile]

I sadly do not know the answer to this. Get a trickle charger and hook it up when you won't be able to drive the car for a while. Just make sure it has settings for the various battery types. My '23 M8 has a lithium battery, while the wife's '23 M550i has an AGM.

[Seaford]

Originally Posted by brlawyer

This may have been asked already, but I will try anyway - due to some stupid, neverending road works in front of my place, it is currently very difficult for me to exit my house garage with the 840d.

So my question is: how long can I keep it there (without running the engine) before the battery runs out?

The answer is ‘many weeks’. I had this during covid lockdown on my 330i. A ‘battery low’ message will eventually appear but in my experience some stuff such as stop/start and comfort access will be disabled before the warning message appears.


As I understand it The technology in these cars is such that the old fashioned way of ‘taking it for a good run’ may not fully recharge the battery.


As above get a good quality battery conditioner and hook it up if you can.not sure what type of battery the diesel has…the 330i and 840i both had AGM. Also charge with the bonnet fully closed.

This is my weapon of choice https://no.co/genius5.

[BigMofoFrog]

Originally Posted by brlawyer

This may have been asked already, but I will try anyway - due to some stupid, neverending road works in front of my place, it is currently very difficult for me to exit my house garage with the 840d.

So my question is: how long can I keep it there (without running the engine) before the battery runs out?

I am often away for 2-3 weeks at a time and my M850i has been fine. I believe it goes into some kind of sleep mode which reduces the background battery consumption. I also have a Thinkware U1000 Dashcam front and back that is on the battery with the radar module and still no issues over the 3 weeks. I believe I may have gone up to a month and all good. Hope this helps.

[AP]

Longest for me is 3 weeks without any issue

[yugrac]

Originally Posted by brlawyer

So my question is: how long can I keep it there (without running the engine) before the battery runs out?

You start pushing your luck at approximately one month, assuming the battery was at 90%+ charge when you park it. Put a tender on the battery if you think you will exceed that amount of time.

[brlawyer]

Originally Posted by yugrac

You start pushing your luck at approximately one month, assuming the battery was at 90%+ charge when you park it. Put a tender on the battery if you think you will exceed that amount of time.

Sorry, what you mean by "tender"?

In any case, I will try to drive it once every three weeks at least - hopefully this stupid traffic will allow me to.

[yugrac]

Originally Posted by brlawyer

Sorry, what you mean by "tender"?

Tender=Charger/Trickle Charger

[brlawyer]

Originally Posted by yugrac

Tender=Charger/Trickle Charger

Tks - decided to move it out into the driveway and left my other car parked at work (I only have easy space outside for two cars, and we have three). This way I will be able to drive either car without having to worry about accessing the garage.

[Qsilver7]

Originally Posted by brlawyer

Sorry, what you mean by "tender"?

A “tender” is a battery charger/maintainer that has the capability to sense when the battery has been charged and turn off…the turn back on if the battery’s voltage drops below a certain threshold. You can keep it connected (in your case to the jump start terminals in the engine bay) indefinitely without OVERCHARGING the battery. These devices come in handy to keep the battery “topped-off” if it is not driven regularly or for long periods of time (like over a month).

The pics below is of the old BMW branded tender/charger/maintainer. BMW contracts their “branded” tender to various other makers. I believe the current tender is made by CTEK. The battery tender pictured below was when BMW used Deltran as their mfg: