Removing battery for winter

[JE92M3post]

My car will be in storage for the winter but won’t have an electrical source to hook it to a battery tender. Can I remove the battery to maintain it for an extended period of time and not have to re-register it or cause any issues when I reinstall it come Spring?

[MaximusB]

Yes, you can remove the battery and don’t need to re-register. No issues. I did that the first year I had my car as I live in an apartment, with no outlet near my spot for a charger. The subsequent years I just unhooked the negative terminal and left the battery in the car. MAKE SURE you folder the back seat first, regardless you take the battery out or unhook the negative. The trunk release won’t work without the battery. You’ll need to unlock the door with the key and crawl into the back and pull the trunk release cable. Last winter I parked my car at my parent’s house and kept it in a charger so I don’t have to deal with all that hassle.

Also don’t start up the car every few weeks during storage in the winter. You’ll introduce moisture in oil. If you do start it, make sure you go for a long drive and get the engine up to temperature for awhile.

[JE92M3post]

Thanks for the confirmation!

[RYDEM3]

I’ll be doing this as well for the winter as I don’t have the luxury of power source for a trickle charger...don’t mean to TJ but how long can we have the car sit for? If we were to say be away for a couple of weeks parked outdoors, still consider unhooking the neg terminal for this duration?

[Scharbag]

If it is parked outside, there are solar options that will trickle charge your battery.

[GtiGyver]

Mine is in a garage with lighting too dim to use as a power source and no outlets in sight.
So far I just left it parked, doors locked with the battery connected.

I was wondering about losing the calibration of the steering angle sensor or other sensors?
Is this the case with extended battery disconnects?

[SYT_Shadow]

Originally Posted by RYDEM3

I’ll be doing this as well for the winter as I don’t have the luxury of power source..don’t mean to TJ but how long can we have the car sit for? If we were to say be away for a couple of weeks parked outdoors, still consider unhooking the neg terminal for this duration?

if the battery dies after a couple weeks of being outdoors you need a new battery

I've gotten through 5 months of having the car sit outside without issues starting it back up in Spring

[RYDEM3]

Originally Posted by SYT_Shadow

if the battery dies after a couple weeks of being outdoors you need a new battery

I've gotten through 5 months of having the car sit outside without issues starting it back up in Spring

Ok so I guess I’ll be disconnecting the neg. terminal then thanks

[SYT_Shadow]

Originally Posted by RYDEM3

Ok so I guess I’ll be disconnecting the neg. terminal then thanks

I mean 5 months without disconnecting anything

Now I run a extension cord and charge it every 3 months

[akkando]

Originally Posted by SYT_Shadow

if the battery dies after a couple weeks of being outdoors you need a new battery

I've gotten through 5 months of having the car sit outside without issues starting it back up in Spring

Probably just make sure you don't go for a bunch of short drives before you park it for two weeks. You want the battery to be changed before you let it sit for extended periods of time.

[RYDEM3]

Originally Posted by SYT_Shadow

I mean 5 months without disconnecting anything

Now I run a extension cord and charge it every 3 months

Sorry I wasn’t being specific, I meant that can I leave the car parked outdoors without trickle charging it for a couple weeks if I had to go on a trip or what not. I don’t have a power outlet to trickle the battery for this coming winter also so I’m going ahead to what was suggested to op for just disconnecting the negative terminal of the battery

[MaximusB]

Originally Posted by RYDEM3

Sorry I wasn’t being specific, I meant that can I leave the car parked outdoors without trickle charging it for a couple weeks if I had to go on a trip or what not. I don’t have a power outlet to trickle the battery for this coming winter also so I’m going ahead to what was suggested to op for just disconnecting the negative terminal of the battery

Just leave it connected and save the hassle. A couple weeks is nothing, providing that your battery is in good shape. Remember to fold down your back seats if you do disconnect the battery. Otherwise you’ll have no way of opening the trunk unless you get another power source to hook up to the terminals under the hood.

[Rajmun340]

It is such a mistake to not drive the S65 in the winter. It gives me significantly more power from the cold air, more than all the typical slap on mods. In fact the difference is so great that i always think about selling my e92 m3 in the summer but change my mind the next winter. As a naturally aspirated engine without direct injection it hates warm air. In fact i consider the e92 m3 a winter only sport car. Could not understand how people in Cali or Florida live with it. It must be vanity but i need the performance to like a sports car. I guess if you ever experience it in cold german temperature you will hate it in the summer.

[6ixSpd]

If you can't connect a trickle charger to it, simply disconnect the negative terminal and you're golden. I've never removed the battery itself while winter storing cars for 5-6 months for the last 12 years.

Be sure to fold down the rear seats or leave something blocking the trunk from fully locking in order to have access for reconnection.

Never had an issue. You won't lose any calibrations or sensor issues, lol.

[Helmsman]

Originally Posted by Rajmun340

It is such a mistake to not drive the S65 in the winter. It gives me significantly more power from the cold air, more than all the typical slap on mods. In fact the difference is so great that i always think about selling my e92 m3 in the summer but change my mind the next winter. As a naturally aspirated engine without direct injection it hates warm air. In fact i consider the e92 m3 a winter only sport car. Could not understand how people in Cali or Florida live with it. It must be vanity but i need the performance to like a sports car. I guess if you ever experience it in cold german temperature you will hate it in the summer.

Yes it is a significant difference in response and power depending on temperature. Last Summar was unusually hot with temp around 30C, car felt surprisingly slow. While coming below 10C it feels monster. Fortunately its quite happy in between...

[Helmsman]

Originally Posted by Rajmun340

It is such a mistake to not drive the S65 in the winter. It gives me significantly more power from the cold air, more than all the typical slap on mods. In fact the difference is so great that i always think about selling my e92 m3 in the summer but change my mind the next winter. As a naturally aspirated engine without direct injection it hates warm air. In fact i consider the e92 m3 a winter only sport car. Could not understand how people in Cali or Florida live with it. It must be vanity but i need the performance to like a sports car. I guess if you ever experience it in cold german temperature you will hate it in the summer.

Yes it is a significant difference in response and power depending on temperature. Last Summar was unusually hot with temp around 30C, car felt surprisingly slow. While coming below 10C it feels monster. Quite temp sensitive for being an NA engine.

[Rajmun340]

Originally Posted by Helmsman

Yes it is a significant difference in response and power depending on temperature. Last Summar was unusually hot with temp around 30C, car felt surprisingly slow. While coming below 10C it feels monster. Quite temp sensitive for being an NA engine.

Hi Nick, "monster" exactly, when temperature is < 8C. I keep an eye on the weather when it's not freezing but dry. It's the most fun time of the year for driving it. My accord does the same in winter at a smaller scale (also NA).
I can only imagine if the S65 was direct injection NA instead of port, it would probably give an extra 30-40 HP. i think the S85/S65 would have inspired another generation of bespoke engines in 2013, with FI added (it also reduces consumption significantly), but the 2009 financial crisis hit auto manufacturers hard and the M division might have had to abandon exotic bespoke designs and use the same weenie 3.0L engine block that equips nearly all bmw's including the F8x M4/3 + added tuned mitsubishi turbo on it. The difference in workload was definitively much reduced from the S85/S65 to the S55 engine design at the M division. A total change of philosophy and budget. It's also possible they lost the M division engineers who designed these bespoke engines.