[AP]

With most if not all of us locked down at present and certainly where I am, not able to drive the car.
Concern is about keeping the battery charged when you don't have access to an external charger.
My plan is to start the car and let idle for 15-20minutes each week, rev it a bit once its warmed up and run the A/C on max along with moving it about in the garage to exercise the systems.

my question though is how do you tell how charged up the battery really is?
Its not an option to display within the hidden cluster menu.

Anyone know how you might determine this - is it possible?

[ztx84]

Not sure if there is a way of getting the data from the cluster (if anyone else knows that would be very helpful!)… but, does the battery charge effectively at idle speed? With mine I'm taking it on just a short drive once a week - 10 miles or so... I have a full tank of fuel, I don't stop anywhere, but I think this is likely to be the best way to keep it all working ok! Hopefully the lockdown passes soon, I imagine we are in for another 3-4 weeks though.

[Warp Ten]

Idling for 15-20 minutes will not charge a BMW battery; you should drive it for a half hour or so at normal speeds to have any impact on the charge. I would recommend a float charger if you are going to let the car sit for several weeks. I swap my BMW with my Corvette on a lift and in the warm weather the BMW can be up for two or three weeks, maybe longer. I always put it on a float charger if I think it will be up for two weeks or more. Never have had a problem with it. In the winter I leave the Corvette up with a charger on it all winter, and in the summer if I think it will be up for more than a couple weeks I will also put it on a charger. All of today's' cars have parasitic drains that can deplete the battery in a few weeks. --Bob

[jlin101]

Agreed, running the car in idle while the AC is on full blast will not charge but deplete the battery, not to mention filling the garage with exhaust, even with the garage door open. If driving the car on the road is not an option, it's much simpler to use a float charger. Modern cars have significant parasitic drain, with all those pumps, sensors, computers and alarm running in the background. Every time you open the door on a BMW, the ambient lighting and instrument display stay on for at least 10 min, unless you use the controller to shut the vehicle off.

[AlteBMW]

OP says he does not have access to an external charger. So it is driving to charge because he has no other option. One thing I would recommend is making sure the car is locked but even in locked state there will be some current drain.

[AP]

So in summary, idling no matter how long will not charge the battery?

[Shatter]

Originally Posted by AP

So in summary, idling no matter how long will not charge the battery?

BMW's brake energy regeneration system is designed so that the alternator charges the battery to maximum of 80% of it's full capacity and then switches off the full time charging, last 20% is charged by engaging the alternator on braking or applying motor braking.

So in short, no idling the engine for even a full year won't charge the battery more than 80%.

[AP]

Ok not worried about getting it to more than 80% , just to reasonable level to offset what is list when it is just parked up for sometime.

[FMIB]

When I collected my new car in Oct 2017, 1 week later I put it in storage for nearly 4 months. On a cold Feb morning it fired into life as new without any running or charging of the battery over the storage period. Hope this helps

[AP]

K ok h , that's good to know

[Dephead2004]

There is a way to access the voltage of the battery!
You enter the service menu by pressing the start button 6 or 8 times within 3 seconds with engine off. It's a mine of information.
Will have to look up how to scroll through all the data.
also how to fine tune the mpg in this menu.
BEWARE there is a data reset somewhere towards the end of the menu. AVOID

[AP]

yeh, familiar with the hidden menu, posted about it here
https://g30.bimmerpost.com/forums/sh....php?t=1415845

I'll have to have another look as I don't recall seeing anything as regards battery charge or voltage in there.

Found this for the M5 which presumably is the same , don't see anything to do with battery in there either though.
https://www.evolveautomotive.com/blo...-tutorial.html

so as I say without access to an external charger or any tools, not looking easy to determine.

[Dephead2004]

ok will of that doesn't work you can buy a small plug into the cigarette lighter voltage meter. I've got one with a usb built in too. https://www.ebay.co.uk/itm/New-LCD-C...edirect=mobile

[AP]

Thanks , interesting

[timmahh]

For what it's worth.. my Connected Drive app just popped up with this tip, making it 'official' from BMW:

Start your vehicle and let it run for 10 - 15 minutes to warm up up the engine and fluids and to keep your battery in good health (please check your local idling laws).

[AP]

Thanks. That's interesting indeed and very timely.