Winter Storage Battery Removal

S

Spahr

Member
I sadly have to put my newly acquired 2003 E85 in an unheated garage for the next six months. There is no power for a battery maintainer and I’m sure the nearly new battery will be stone dead in six months. I don’t have any option but to remove the battery and put it on a maintainer in my house.

I read “LIFETIME MAINTENANCE SCHEDULE” by Miller and he suggests removing the battery sometimes cause components to fail when re-installed. Sounds odd to me but I have no experience with BMWs.

Any thoughts or ideas? Or even better, experience with long storage times?
 
There should be no problem (other than you car will not be alarmed). The idea that some components could fail when you reconnect it is nonsense.

The issue that you sometimes hear about is the car going into 'transport mode' but this function is supposed to be deleted by the dealer when the car has it's PDI when first sold. Occasionally it isn't done properly because of lazy dealers, the result is that the car disables some systems (like air-con, heated rear screen, blower fan) when the DME sees a gradually declining battery voltage over a period of time. Just removing the battery should never cause transport mode to be activated in theory (especially if you touch the battery leads together as soon as the battery is removed).

A fully charged battery that is disconnected will have no problem being stored for 6 months even without a maintainer on it. Manufacturers / retailers regularly store them for this length of time when new.
 
I've just bought a battery disconnect switch, so you don't have to take the lead off and reconnect.

https://www.amazon.co.uk/gp/product/B07W3PLDPS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
 
MKZ4000 said:
I've just bought a battery disconnect switch, so you don't have to take the lead off and reconnect.

https://www.amazon.co.uk/gp/product/B07W3PLDPS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
Click to expand...

This will only isolate the battery, it won't maintain or charge the battery. Which I believe is what the OP wants (mentions storage for 6 months).

"According to BMW, a car battery should sit for four weeks without removing the battery. When the battery is removed, it can stay for six weeks to 6 months. However, you need to keep recharging the battery over time. Ideally, the battery should be recharged every 12 weeks when the battery is disconnected."
source

I doubt mine would last 4 weeks... but I'd still recommend charging up again every 2-3 months.
 
What about considering a solar panel trickle charger mounted outside the garage and wired to the battery?
https://www.ebay.co.uk/itm/AA-12V-Solar-Powered-Car-Battery-Charger-Panel-Motorhome-Caravan-Trickle-Charge/224137569780?hash=item342fa3e5f4:g:LeUAAOSw2bVfSpLa
 
I've had the battery off mine for various periods and the only issue has been needing to re-set the clock and auto window functions, both of which are quick and simple. Insurance might be an issue as you won't have an alarm or immobiliser activated (but a battery-less beemer is tricky to steal). Otherwise I can't see a problem with leaving the battery off.

I'd be more concerned about the usual storage deterioration like brakes binding and the fuel pump becoming noisy and or sticky, which seems to be an emerging issue with stored cars, possibly due to changes in fuel composition?
 
Thanks for the info!

In past years when we went south for the winter I had a small solar panel & controller that sat on the dash board of my old “beater” and even through the windshield the solar setup kept the battery at 100% I didn’t disconnect the battery from the car either. But this storage area is an indoor commercial unit and I can’t install solar.

The tires are old so I plan to replace them first thing when I get back.

Hopefully next year I’ll be able to take it south and enjoy it all year long.
 
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