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Discussion Starter #1 (Edited)
When I first bought my M5 3 years ago I bought a brand new key from the dealership. You know, one that was all fresh & shiny new. And one where you could actually read what the buttons say on them.


But my question is about the OLD KEYS I still have. I have 2 old keys to my car that I put away in a drawer & they are just collecting dust. I know one method (although it's not the most ideal method) to recharge these old keys is to start the car with them before a long road trip. That way the car is charging them as you are driving. But I don't have the time to do that & as you know our cars are very very thirsty machines. I'm pretty sure that with the key in ignition switch (#1) I -- wont charge at all. BUT, can I put the key in the car & switch it to position (#2) II to charge the keys as I let the car sit there in the garage... ? Or do I have to have the engine running... ? :dunno:


Just curious & my wondering & wandering mind would like to know. THANK YOU in advance for your help fellas...




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When the battery dies and you charge it ,the key wont still work cause it needs to be resynced .There's a vid on how to sync the keys search for it and your keys will work .Check youtube!
 

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As you figured out, the keys charge while the car is on. Just switch out and use the old keys for a while to charge them up. Do this periodically and they should stay fresh.
 

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When I first bought my M5 3 years ago I bought a brand new key from the dealership. You know, one that was all fresh & shiny new. And one where you could actually read what the buttons say on them.


But my question is about the OLD KEYS I still have. I have 2 old keys to my car that I put away in a drawer & they are just collecting dust. I know one method (although it's not the most ideal method) to recharge these old keys is to start the car with them before a long road trip. That way the car is charging them as you are driving. But I don't have the time to do that & as you know our cars are very very thirsty machines. I'm pretty sure that with the key in ignition switch (#1) I -- wont charge at all. BUT, can I put the key in the car & switch it to position (#2) II to charge the keys as I let the car sit there in the garage... ? Or do I have to have the engine running... ? :dunno:


Just curious & my wondering & wandering mind would like to know. THANK YOU in advance for your help fellas...




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Engine off, ign. on (II) with a battery tender should charge the keys. If you're running DRLs code them to off first as they will increase the battery load significantly.
 

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Discussion Starter #6
Thanks for the help fellas. The old keys still work. I just wanted to charge them both up. I will disconnect my DRL & just leave the key in position II for a few hours...
 

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I was hoping my dead would come alive after my 3 hour road trip but it seems its truly dead. Looks like BMW is getting $170 from me :grrrrr:
 

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From KL R, the battery inside the key head is charged inductively by the EWS ring antenna via a coil antenna integrated in the key. The charging process is controlled by electronic circuitry integrated in the key.

Some key tidbits:

- The service life of a radio-control key used under normal conditions corresponds to the vehicle lifespan.

- If the FZV keys are not used (i.e. stored in a drawer), the battery will be discharged after approx. 1.5 years.

- The time required to fully charge a discharged battery is approx. 30 hours.

- The remote control can be operated about 15 times after a charging period of approx. 30 minutes (driving time).

The key data is stored in a transponder chip. The transponder chip is a wireless read and write EEPROM. It is powered via the ring coil at the steering lock. Power is applied electromagnetically when the key is in the ignition switch from KL R.

The power supply is used both for data transfer as well as for charging the battery. This has been made possible by new development of the transponder chip.

As with previous systems, every press of an FZV key also provides the battery charge condition. When the FZV electronics receives a low power condition message three successive times, the GM sets a fault indicating a low battery within a specific key. The LCM is also informed via the bus system and alerts the driver via an instrument cluster matrix message.

If the battery is recharged (used to operate the car), the fault will be automatically deleted when five successive messages are received indicating a charged battery condition.

The battery has no affect on the EWS III communication function!
 

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mattmor, You know a lot about keys! Any idea how the system senses the key being in the switch? My car warns key is in the ignition even when its not. Same with both keys. TIA for any thoughts.
 

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mattmor, You know a lot about keys! Any idea how the system senses the key being in the switch? My car warns key is in the ignition even when its not. Same with both keys. TIA for any thoughts.
Do you have the key with you when it warns you? Chances are that the system is outputting a false signal. It could be anything from the EWS control unit, General Module, ring aerial, T/R (transmit/receive) module or even the key transponder. Difficult to know without testing. Do you have access to DIS?
 

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If the Battery tender is hooked up and key is turned to 2nd position car battery won't die right?…just wanted to give this a shot, as I can't see car pulling much power if fans and lights are off with this idea.
Apples
 

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.....just hook up your trickle charger... :dunno:

I replaced my battery using a computer electronics repair shop. Cost me $35 total. Syncs the two keys together and viola.
 

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.....just hook up your trickle charger... :dunno:

I replaced my battery using a computer electronics repair shop. Cost me $35 total. Syncs the two keys together and viola.
How did you open the key? Do they just pop open?
 

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https://www.youtube.com/watch?v=e1o9vH3mgmg&feature=youtube_gdata_player

I used a utility knife with thick gloves (just in case I slip). Slowly go around the edge and cut shallow. It will come apart after you go all the way around. Remove the circuit board. Take the pieces and a ML2020 or VL2020 battery to your local computer repair shop. Show the repair guy how closely the new solders must be made. Pay a half hour labor. Only do 1 key at a time.

When I got home I put the circuit board (with the battery) back into the cover and I used a rubber band to hold it together very tightly.

With ALL doors closed and unlocked: Take the good key, put it into the ignition, turn to position 2 and then within 3 seconds insert the other key and go to position 2 and immediately remove the key. Attempt to start the car with the backup key.

Once you've done that take the good key and put it into the ignition to position 2 "on" (but not running) and remove the key. Within 3 seconds press and hold the lock button and press the unlock button 3 firm and slow times and release (you're still doing this on the good key still). Wait for the doors to lock then unlock. Within 3 seconds press and hold the lock button on the key with the new battery and press the unlock button 3 times (still holding the lock button).

Still sitting in the car press your good key lock button. Car should lock. Unlock it. Car should unlock. Take the key with the new battery and lock it with the button. Car should lock. Press the unlock button. Car should unlock.

If that works then move on to the final step. I used PVC welder from home depot because it dries clear with no residue. A very small amount around the edge of the cover is all you need and two clamps. Press it together tightly, remembering that it IS old plastic. Also do NOT get any plastic welder / PVC welder on the circuit board.
 

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Has anyone tried using an induction phone charger on their key(s)? Im on my second dead key in 2 years and not really wanting to pay the high cost of another replacement. I tried this using a stand up induction charger, but the key might not be sitting on the correct spot of the charger. I might try a small flat type to see if that works overnight, but wanted to see if anyone here has tried this method yet.

 

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Is that like any wireless phone charger? That's a cool hack.
 
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