My 2005 S entry key won't unlock/lock my Mini anymore. If I hold the button long enough, it might work and might not. I am sure there is a lithium battery to be replaced but how the heck do you get the key apart to change it?

I see some of the newer Minis have rechargeable keys. I'm sure mine isn't one of them.

I don't have my Mini close by or else I would look in the owners manual. It's parked safely across town in a secure garage.

Thanks all.

 

It's a rechargeable battery, but you have to build a charger from scratch. And to get to the battery, you have to break the sonic weld of the plastic in the fob. So, it's either break into your key and try your hand at electrical engineering, or buy a new $150 key from the dealer, or use the metal key as is. Sorry. We're all experiencing the same thing these days.

You try touching the key to your chin when you press the button? Gives you more range.

 

Your key (2005) with 3 buttons is rechargeable. 2002-2004 uses a 2 button key with non-rechargeable battery, and the key case is easily opened for battery replacement.

The receiver for 2005 is located in the rear view mirror. If your key works better when held next to it, either the key is sending a low signal or the receiver is not working well.

Here's a case where replacing the receiver fixed the problem: https://www.northamericanmotoring.co...-receiver.html
And a case where the key was the problem: https://www.northamericanmotoring.co...eable-key.html

 

Hey everyone,
Thanks for the great but sad information. Thankfully I have my other key that still works, so I'll just use it.

Sure cant afford a new key/fob right now.

This forum is just the greatest bc everyone wants to help each other!

 

had the same problem with my 05 mcs. Did a search on NAM, and there are several threads that show simple step on reprogramming key. Worked like a charm.

 

I thought the three button keys have a rechargeable battery and that the battery gets recharged in the ignition. If not, what would recharge it?

I don't understand the comment about building a recharger from scratch- wouldn't it be a matter of replacing the rechargeable battery (they do lose their ability to be recharged) then glueing the case back together or putting the components into a new case if desired?

To the OP- I've worked on lots of the '02-'04 clamshell style keys, as the cases seem to be a bit easier to wear out with the buttons breaking, etc. I've got a thread going in the "how-to" section if you want to take a look. The lithium batteries in there are an easy pop-out/pop-in replacement, but I have also replaced a number of button switches that have been broken off from use after the outer button being broken. I am willing to have a look at your key to see if the battery can be replaced. Let me know if you want some help with this.

Val

 

I ripped open my key fob one day. Looked up the battery. It already IS a rechargeable battery, there is just no circuit to recharge it.
NO it does not recharge via ignition.
No, you can't easily replace the battery. It is soldered in place.
Yes, you can buy new batteries of the same style with similar enough connectors that if your handy with a soldering iron, it can be done.
New batteries are only like $3.
Yes, you can build a charger. I forget who makes the battery, but if you look it up, the manufacturer supplies a schematic for a charging circuit on their site specifically for that battery.

One day, I plan on building said charger, and using a mini or micro USB port on the key fob to recharge the battery whenever I want. Only crappy part is that I cannot re sonic weld the key back together, so I guess I'll have to super glue it or something else similar.

 

Maybe a matter of semantics, but it does recharge when in proximity to the ignition switch, via inductive (wireless) charging.

 

Wonder if those inductive proximity chargers for cell phones would work on our keys?

 

OP: I might have steered you wrong about fixing the key. I stumbled upon a couple of sites that fix the very similar BMW three button keys. Taking apart the sonically welded key is very tricky and there are pictures on one of the sites of mangled circuit boards, which is probably what happens when the inexperienced try to take apart this type of key:

http://bmwkey.com/

http://www.bmwgm5.com/Key_Repair.htm

I would strongly suggest you send it to one of the experts. I'll stick with the simpler, clamshell type keys.

Val

 

I don't know why people don't believe me on this inductive thing. There IS NO INDUCTIVE CHARGING CIRCUIT on these R53 keys.

I have a degree in electrical engineering. I know what an inductive charging circuit looks like. There IS NO COIL in the key fob for charging.

For those who don't believe me, I persuade you to break open your key and prove me wrong. If there WAS such a circuit, then wouldn't we all have great range all the time on our keys, instead of the range slowly and surey getting worse and worse!? Bc I know my key has gotten crappier in the past 2 years of owning it!

 

hmm, I really don't know what is inside of these keys - but I hear on one hand it does not have a consumer replaceable battery, but that it is rechargeable but where exactly does that recharging happen? I am pretty sure it is not charging up in my pants pocket, so,... ? It is not rechargeable then? Is that what you mean? That the battery wears out in, oh, say five years or so? Would your degree help us predict how long the battery lasts?

So, here is my point, when I push the key slot in without the key, I can see no place where there is metal to metal contact and examining the key fob itself does not reveal a metal contact point. I surmise that there is some sort of "field effect" that is exchanged through the plastic. You say that is only used for exchanging the "security key" to start the car and not to charge it. But --- it must have some sort of inductive coil inside of the key to accomplish that, an antennae of some sort?

 

Not "consumer" replaceable.
It IS rechargeable, I looked it up on the manufacturers web site.
There is NO recharging Circuit built into the key. That is the issue.
It wears out depending on its use. If I remember correctly, it should be about a 6year battery.

Id take pics, but that key is in FL, and I'm 3k miles away in south Dakota.

 

Then you should explain it to us. The Owner's Manual says:

In every master key with remote control,
there is an extended-life battery as a power
supply that is charged automatically in the
ignition lock as you drive.

You should therefore use each master key at
least twice a year to maintain the charge status.

My keys are now over 7 years old and the remote works fine.

 

The BMW WDS (Wiring Diagram System) manual has this note:

 

My key for the 2008 Hatchback (which is the R56 model) does not look like the picture of the Comfort Access model key, which has a removable back to replace the battery. The Owners Manual for 2008 clearly states it is charged in the ignition.

So, it is only the R53 models that do not have this recharging circuit? OP has a Gen 1 (2005), but it still does not have a replaceable battery or a rechargeable one? But some later Gen 1's do have it? Or is it the comfort option on a Gen 1 that offered that?

 

2002-2004 Gen 1 have replaceable battery.
2005+ Gen 1 have rechargeable battery.

 

I've also got an AA in electronics- from a two year trade school for "Communications Electronics" a long time ago. I also have 25+ years working with electronics and repairing things for myself, others, and now in a maintenance shop at a major market TV station along with operating a satellite truck when needed to do so.


There is no way they would put a rechargeable battery into a car key without some way to recharge it. Rechargeable batteries work well, when they can be recharged. They also have a lower output voltage to start with compared to the equivalent alkaline/lithium battery (1.3-1.4 volts to start for a AA compared to 1.6 with an alkaline battery) and have a definite "voltage cliff" that they drop off of. The advantages are longer life (compared to say, the CR2032 batteries in the '02-'04 clamshell remotes) and making a key that is ultrasonically welded together and seems more "finished" than the pop apart clamshell keys.

If you look at the key fob hall of shame on the bmwgm5 site I previously posted, you can see the inductive coil on some of the circuit boards. The site owner explains that it is for activating the EWS chip, but I believe that is also charges the battery as well. I know in the '02-'04 boards there is no inductive coil, as I have had many of them apart to repair them.

The fact that there is a rechargeable battery in there along with the information contained in the owners manual leads me to believe that the battery is inductively charged.

Val

 

This is the key, not all keys are alike. OP should be able to recharge his in the ignition if he can get into the car. I still wonder if those inductive chargers for cell phones would work on the later model keys like his? I mean, how can it hurt, he is locked out now.

 

Wow, plenty of people going off on tangents in here.

 

And the different key thing strikes again. Not to beat a dead horse since several here have explained the difference, but there is definitely a recharging coil in the 05+ R53 keys. I had thought about trying to change over to the newer keys instead of what I went through in my thread:
https://www.northamericanmotoring.co...-question.html

 

Feeling glad that I have a 2-button key