charging the key

[71amx]

Hi I have a question. one of the key on our Z4 doesn't work to lock or unlock the doors. I read that these have a rechargeable system that charges the key battery when it is in the ignition with the car running. I drove it on the highway today for about 40 min with that key and when I got out, it still wouldn't lock the doors. Does it take longer than that for the key to get enough charge to lock the doors or do these go back and can just the battery be replaced or do you have to replace the entire key (hopefully not the latter)?

Thanks

[Punisher3.0si]

It is replaceable but requires surgery since the plastic has to be cut open. There are plenty of youtube videos showing how to do it. It has to be programmed once it's replaced.

[antennahead]

One of my keys is about dead as well. I used to swap them out monthly, but got very lazy about it over the last year as I was dealing with an ill parent. When I finally swapped them a few weeks ago, the key that had been sitting for a year would not charge well, After a week of hit and miss remote operation standing right next to the car, I went back to the working key, wanting to at least have one fully charged.

I've seen guys here report using an aftermarket company that cuts the keys open and replaces the battery. Typical BMW to require you to buy a new key at a ridiculous price My old Lexus key had a replaceable battery.

[71amx]

That sucks. I was thinking how smart to put a rechargeable battery in the key instead of one you have to change. Now I am thinking a $2 conventional battery is a much better way to go. When I looked at the key, I was thinking it doesn't look like it was meant to be taken apart. Now I know why.

[itdnwiwbp]

I've always thought some sort of key charging dock would be cool for this reason - kind of like a watch winder. Probably impractical due to the number of different types, etc. but it sure would be handy for those of us who don't drive our cars often or don't remember to switch keys periodically.

[Hawkeye]

my backup key hasn't been used more than once a year for the past 10 years and last time it did get used it had about the same charge and range as my daily key.

[koruptor]

It takes 30 hours of total driving to fully charge it, though you can actually get it to start working after 30 minutes of driving.

Before replacing the internal battery or paying for an overpriced replacement, try re-initializing the key first.

See "Remote Key Initialization" here.

[3GFX]

Originally Posted by koruptor

It takes 30 hours of total driving to fully charge it, though you can actually get it to start working after 30 minutes of driving.

Before replacing the internal battery or paying for an overpriced replacement, try re-initializing the key first.

See "Remote Key Initialization" here.

Thank you, this is great key information!

[71amx]

Thanks, I will try the initialization process on this key and see if that works. How do you tell how much charge in on the key? There is nothing I can see when you push the buttons that even indicates anything is working let alone % charged. Also, I read in the owners manual where the key should be able to roll down and roll up the windows automtically by clicking the unlock (to put down) and lock (to put up) button twice and holding the second click (my dodge Ram does this) but I tried it multiple times with the good key and that doesn't work either.

[koruptor]

Originally Posted by 71amx

Thanks, I will try the initialization process on this key and see if that works. How do you tell how much charge in on the key? There is nothing I can see when you push the buttons that even indicates anything is working let alone % charged. Also, I read in the owners manual where the key should be able to roll down and roll up the windows automtically by clicking the unlock (to put down) and lock (to put up) button twice and holding the second click (my dodge Ram does this) but I tried it multiple times with the good key and that doesn't work either.

There's no way to tell what the charge level is on the key. It's either charged enough or isn't.

To roll down all your windows (coupe), or all windows and top (roadster), you have to hold the unlock button. Don't just press it, but hold it. And after a few seconds the magic starts to happen. But if you let go of the unlock button too soon, it'll stop the operation. I own a coupe, so the windows will stop where they are if I let go of the button. I'm not sure what happens with roadsters if you let go of the button while the top is in the process of opening.

I've never been able to roll up the windows with any combination of button presses on the remote. I've resorted to just turning the key in the door lock when necessary.

[GuidoK]

Originally Posted by koruptor

To roll down all your windows (coupe), or all windows and top (roadster), you have to hold the unlock button. Don't just press it, but hold it. And after a few seconds the magic starts to happen.

That doesnt work on a stock pre-fl z4 of his vintage.

[koruptor]

Originally Posted by GuidoK

That doesnt work on a stock pre-fl z4 of his vintage.

Thanks for the correction!

[pungo]

Originally Posted by koruptor

I've never been able to roll up the windows with any combination of button presses on the remote. I've resorted to just turning the key in the door lock when necessary.

I coded my car to allow the windows to go up with the key. I think it's a safety thing in the USA so people don't sue if they get injured?

Though I more so use the windows down when walking toward the car on a hot summer day, using the key on the chin method for the extra range.

[koruptor]

Originally Posted by pungo

I coded my car to allow the windows to go up with the key. I think it's a safety thing in the USA so people don't sue if they get injured?

Though I more so use the windows down when walking toward the car on a hot summer day, using the key on the chin method for the extra range.

It's been a while since I've coded my car, but yes I think it's in the GM5 module.