Disconnect battery - part 3

2003 300i

Another follow up to my original post on the same subject. The car is parked outside in a carport with no power outlets - no option of connecting a battery tender when I leave it untended for weeks or longer. I plan on disconnecting the battery in that case with a quick disconnect tool on the negative post. But I've heard from several people that if I lock the car doors beforehand and then close the trunk with the battery disconnected, I won't be able to unlock anything with the key. Could that be true?

You won't be able to unlock anything with the buttons on the key. You'll still be able to stick the key in the trunk and open it, or stick the key in the driver's door and open it. The only thing that's slightly hard to do with the battery disconnected is open the driver's door on a coupe, since coupes normally roll the window down a little bit on opening.

Thanks. What I meant to say was, "I won't be able to unlock anything using the key manually." Your answer tells me I can. But my original query didn't include 2 youtube videos I came across. The first at refers to the problem in an E32 and E34, and it offers a solution. I thought it might be the same with my E46. The second video at is for an E46 and offers no resolution.

All that got me to thinking.

A battery in good condition will go for months left connected.
Verify that your mechanical key locks work. Failure of these is not unheard of.

In video 2, "look how smoothly this glides" means the mechanism is broken.

Leave my car for two months at a time with a sound battery and starts every time.