[fuzzy123]

So... I recently got a new card holder to replace my wallet and am LOVING the lightness in my pockets, so i'm really interested in further lightening my pockets...

I have comfort access, so I wanted to see if there was a way to open open up an existing keyfob and place it into something the size of a credit card so that I don't need to carry around the bulky key fob?

May sound like a crazy idea, but I'd LOVE it if I didnt have to carry anything but my tiny card holder and phone.

[deanmc]

That actually would be a great idea...until your car battery dies and you don't have the valet key, or you lose your wallet somewhere. But in theory, yes, it would be awesome. Go for it!

[fuzzy123]

Originally Posted by deanmc

That actually would be a great idea...until your car battery dies and you don't have the valet key, or you lose your wallet somewhere. But in theory, yes, it would be awesome. Go for it!

Car battery hasn't died ever, and i keep really good track of my wallet, and if i do lose it, i'll just call a buddy to grab my key from the house or something, just like I would do if I lost my key now. I'd love to actually do this. I just don't know where to start..


Anyone got any tips on how I can go about doing this?

[SS e93]

take a hammer and smash your key till its as flat as a card. i know lexus had a comfort access wallet key. i am surprised BMW has not developed one openly. but then again, its an UPGRADE OPTION, which should be standard at this price point by now.
the main issue is how strict key registry is.

[ibimmer954]

The CR2032 battery alone is about double the thickness of a credit card. And that's before the circuit board which is probably a little thicker than the battery. The final project will still be a bit larger than a credit card, but you might be able to make it smaller than it is now. Assuming you have a way to cover the battery and are willing to give up the buttons to lock/unlock the doors. You'd have to crack open the plastic key case with a little Dremel tool or something, hack apart the current circuit board to remove the buttons, and mount the whole thing in something smaller. I certainly wouldn't be brave enough to try it.

[fuzzy123]

Originally Posted by ibimmer346

The CR2032 battery alone is about double the thickness of a credit card. And that's before the circuit board which is probably a little thicker than the battery. The final project will still be a bit larger than a credit card, but you might be able to make it smaller than it is now. Assuming you have a way to cover the battery and are willing to give up the buttons to lock/unlock the doors. You'd have to crack open the plastic key case with a little Dremel tool or something, hack apart the current circuit board to remove the buttons, and mount the whole thing in something smaller. I certainly wouldn't be brave enough to try it.

Does the RFID chip require power? i thought it was just detected by the car, either way.. something a little thicker than a CR 2032 would be sufficient for me... Also I dont need lock/unlock or anything... All I want to do is be able to access the vehicle

[wareagle900]

your problem would come when and if the battery died in the key fob. Since it would be modified there would be no way to charge it.

[GenePoole]

Originally Posted by fuzzy123

Does the RFID chip require power? i thought it was just detected by the car, either way.. something a little thicker than a CR 2032 would be sufficient for me... Also I dont need lock/unlock or anything... All I want to do is be able to access the vehicle

The RFID part of the FOB doesn't require power. The rest of the FOB functionality (remote door opening, etc.) uses the internal battery.

[Ron1n]

Originally Posted by wareagle900

your problem would come when and if the battery died in the key fob. Since it would be modified there would be no way to charge it.

CA keys don't get charged. The batteries can only be replaced.

[fuzzy123]

Originally Posted by GenePoole

The RFID part of the FOB doesn't require power. The rest of the FOB functionality (remote door opening, etc.) uses the internal battery.

Well, I dont need any of the other functionality since the handle does all that(lock/unlock/trunk) ...

So theoretically I can just take out the rfid chip and somehow make it fit into something the size of a credit card and be good to go?


And I still have my spare FOB if I ever need a full functioning fob..

[wareagle900]

Originally Posted by Ron1n

CA keys don't get charged. The batteries can only be replaced.

you can't pop the start button off and insert the key? Thats the usual way.

[MikeLogan]

bump, any luck?

[Ron1n]

Originally Posted by wareagle900

you can't pop the start button off and insert the key? Thats the usual way.

Pop the start button off?

The CA keys aren't the same as the normal keys. Normal keys get charged when you put them in the slot. CA keys don't.

[wareagle900]

In a mercedes with "CA" the key can be charged by popping off the start button and sticking it in the slot as normal. I just assumed that was how they all were... my bad...

[MikeLogan]

Originally Posted by wareagle900

In a mercedes with "CA" the key can be charged by popping off the start button and sticking it in the slot as normal. I just assumed that was how they all were... my bad...

Don't you EVER compare our cars to Mercedes, EVER.

JK :-)

[wareagle900]

well the only reason i referenced it is because in my family there are 5 mercedes and only 1 BMW..... And not one of the mercedes comes close in performance and feel.... and one of them happens to be a 150k special addition! Although i will say that they have a higher interior quality.... for 2 to 3 times the price! lol BMW FTW

[MikeLogan]

Originally Posted by fuzzy123

Well, I dont need any of the other functionality since the handle does all that(lock/unlock/trunk) ...

So theoretically I can just take out the rfid chip and somehow make it fit into something the size of a credit card and be good to go?


And I still have my spare FOB if I ever need a full functioning fob..

The RFID chip needs power.

I figured, like you guys said, the CA door will still open if it detects the RFID chip...so I removed my FOB battery to try it...zilch. Comfort access(getting in the car, and starting it) requires the battery powering the fob/rfid.

[GenePoole]

Hmmm. The valet key in the glove box doesn't need any power.

[GenePoole]

(This is all based on non-CA system.)

I had a useless fob I bought off ebay for the roundel emblem. I decided to take it apart. I unsoldered the battery from the board and stuck the board into the slot. Nothing. If you stick the valet key itself (removed from its fob-shaped cover) it will activate the car, but the bare board did not. This would seem to support the "battery needed" hypothesis, but I took it one step further. I put the board back in the FOB case as best I could (it got pretty destroyed getting it apart) without the battery and it DID acknowledge its presence with the circle/slash key icon on the dash.

Conclusion: Battery is not needed, but with the RFID in a normal FOB, the FOB shell must be present to push a switch or something mechanical to let the system know that it is there. The valet key doesn't seem to have this restriction and will activate the system by just being present in the FOB slot.

Pics:
http://hoxnet.com/p/FOB/

[wareagle900]

It is only logical that the battery is required. Sure there is an rf chip but it only gives off a signal when powered.... How else would a signal be transmitted without power!

[GenePoole]

Did you even read my post?

Search for Passive RFID.

[MikeLogan]

Originally Posted by wareagle900

It is only logical that the battery is required. Sure there is an rf chip but it only gives off a signal when powered.... How else would a signal be transmitted without power!

I guess I (he) figured it was an RFID chip that doesn't require power, for example, like the RFID chip in an access fob, access card, credit card, etc...