Forgot my key today...

[jerry33]

If the battery is out of the fob that long, won't it "forget" its programming?

The programming is in the car, not in the fob. The car is programmed to accept input from particular fobs.

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Interesting note, At first I tried to unlock the car with the unpowered fob but I could not find the "special spot" near the passenger wiper that is supposed to sense the key in the event of a battery failure.

The special spot won't work with a totally dead fob. It's just near the transceiver so that a fob with a weak battery will be able to access it. Remove the battery and you can't use the fob at all. If you could, there would be a slot to insert it as there is on the Prius (inside the car).

 

[FlasherZ]

The special spot won't work with a totally dead fob. It's just near the transceiver so that a fob with a weak battery will be able to access it. Remove the battery and you can't use the fob at all. If you could, there would be a slot to insert it as there is on the Prius (inside the car).

I thought the "special spots" were an RFID scanner that could energize the tag inside the FOB (a la passive tag), when its role as an active tag was no longer working. I thought that meant that even if the FOB was completely dead, it would still work.

 

[andrewket]

I thought the "special spots" were an RFID scanner that could energize the tag inside the FOB (a la passive tag), when its role as an active tag was no longer working. I thought that meant that even if the FOB was completely dead, it would still work.

This was my understanding as well, and how a few of my previous cars have worked.

 

[kendallpb]

I'd imagine that the programming information is stored in a piece of non-volatile memory. So as long as the memory doesn't get corrupted (and it shouldn't, because they are using automotive qualified electronics parts that have higher standards), it doesn't matter whether it's powered or not.

It must be as you say, otherwise how does one replace a dead battery without reprogramming it? ;-)

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The programming is in the car, not in the fob. The car is programmed to accept input from particular fobs.

Um, or what you say; ignore my previous comment. ;-)

 

[jerry33]

This was my understanding as well, and how a few of my previous cars have worked.

That is how my previous cars worked too. I had read that the Model S was different. Anyone know for sure?

 

[dsm363]

If you keep your key fob attached the the physical house key, you'll be less likely to forgot it.

 

[brianman]

That is how my previous cars worked too. I had read that the Model S was different. Anyone know for sure?

Given the first sentence's reference to battery, I presumed the second sentence was referring to the key's battery rather than the vehicle's battery. But perhaps I was misinterpreting:

If the key doesn’t work, you may need to change its battery. To open doors
using a dead battery, use the emergency unlocking procedure (see page 28).

If the vehicle doesn’t unlock when you walk up to it, or when you press the unlock button on your key, position the key near the base of the passenger side windshield wiper, as shown. Then press the front passenger door handle to open Model S.
IMPORTANT! If a message on the instrument panel tells you that the key can’t be detected, place it in the cup

Update: I tried every "lower windshield to partly under frunk lid" position I could reach from the passenger side with a battery-less FOB and couldn't get it to respond to the passenger door handle tap. Bummer.

 

[FlasherZ]

Update: I tried every "lower windshield to partly under frunk lid" position I could reach from the passenger side with a battery-less FOB and couldn't get it to respond to the passenger door handle tap. Bummer.

Did you try a battery-less FOB in the cupholder to start the car? Perhaps that one works without a battery but you need at least a low-battery FOB to open the doors? I don't know, really.

 

[brianman]

Did you try a battery-less FOB in the cupholder to start the car? Perhaps that one works without a battery but you need at least a low-battery FOB to open the doors? I don't know, really.

I might at some point, but that case is less concerning to me than the "I'm locked outside in bad weather/neighborhood" problem.

 

[GasDoc]

Did you try a battery-less FOB in the cupholder to start the car? Perhaps that one works without a battery but you need at least a low-battery FOB to open the doors? I don't know, really.

Nope. I tried this with a fob with the battery removed and the car did not recognize it. Apparently you need some minima charge.

 

[brianman]

Nope. I tried this with a fob with the battery removed and the car did not recognize it. Apparently you need some minima charge.

... or the feature is not working properly. I suspect the former (your assertion) though.

 

[Al Sherman]

Have we decided if the extra key FOB WITHOUT battery hidden inside the car will work if you lose your key? ie: grabbing the extra FOB and putting a battery in to start the car 'til you can get home to your spare FOB? If so, I'm going to do this. Extra FOB and separate battery hidden in the car. Unlock the car with the app, and then put the battery in the FOB to drive. But, have we decided if this will work as far as the FOB without the battery not causing any issues, or losing programming?

 

[GasDoc]

Have we decided if the extra key FOB WITHOUT battery hidden inside the car will work if you lose your key? ie: grabbing the extra FOB and putting a battery in to start the car 'til you can get home to your spare FOB? If so, I'm going to do this. Extra FOB and separate battery hidden in the car. Unlock the car with the app, and then put the battery in the FOB to drive. But, have we decided if this will work as far as the FOB without the battery not causing any issues, or losing programming?

This worked for me. I removed the battery and found out that they fob would not register at the winshield spot or the cupholder.

I recently went to get paint armor installed. I had to do an evening drop off and they didn't have a drop box. So I put my key and battery in an envelope and parked at the installer's shop. I locked the car with the app and left it there overnight. In the morning, the installer called me when they were ready to move the car and I opened it up with the app. The put the battery in the key and all was well.

No way to test this, but I suspect that this would be fine over a long term as it would make sense for the key to use non-volatile storage.

 

[jerry33]

Have we decided if the extra key FOB WITHOUT battery hidden inside the car will work if you lose your key? ie: grabbing the extra FOB and putting a battery in to start the car 'til you can get home to your spare FOB? If so, I'm going to do this. Extra FOB and separate battery hidden in the car. Unlock the car with the app, and then put the battery in the FOB to drive. But, have we decided if this will work as far as the FOB without the battery not causing any issues, or losing programming?

The programming is in the car's security ECU, not in the fob. Removing the battery from the fob won't cause any problems (other than insurance problems if it gets stolen and the thief knows enough to insert a battery).

 

[araxara]

Removing the battery from the fob won't cause any problems (other than insurance problems if it gets stolen and the thief knows enough to insert a battery).

What is all this talk about a battery for the FOB? I thought if your battery dies, then all you need to do is place the FOB in one of the cup holders to turn on the car.

-----
Never Mind. I just tried that with my car and it doesn't work. The battery is needed.

 

[neroden]

I was thinking about putting my spare key fob into one of these:
Amazon.com: Black Hole Faraday Bag - RF Signal Isolation for Forensics, Standard Window Size: Camera Photo
and then putting it into the glove box. Do you think it will work? Much easier than removing the battery

I got a different company's model (RA Mayes makes a cheaper Faraday bag), but I can confirm that it works for preventing the car from thinking there's a key present.

 

[carrerascott]

Somewhat back to the original issue here, keep in mind if you have your key in your pocket and are showing someone the car, they can hop in the drivers seat and drive away. As long as they don't stop and get out, they can drive it until the battery dies... this definitely needs to be fixed.

 

[kishdude]

Somewhat back to the original issue here, keep in mind if you have your key in your pocket and are showing someone the car, they can hop in the drivers seat and drive away. As long as they don't stop and get out, they can drive it until the battery dies... this definitely needs to be fixed.

I don't think that this is such an easy fix. If they set the software such that if the car doesn't sense the battery after being turned on, then you will get many situations where in legitimate circumstances when a driver has the key in the car but the battery is weak, the car will stop which is not a good situation. All other keyless cars that I've owned have worked the same way.

1) Key must be present in the vehicle to start
2) once started, the car will continue to run but will warn you if it does not sense the key.

This seems to work well and should be how the Tesla should work. Can anyone confirm that the car doesn't warn you if the key is not in the car? It seems to me that my car does warn me, but I haven't tested this specifically.

 

[carrerascott]

It has warned me at times, but if I have the key on a hook near the car it doesn't, and once I drive off I didn't notice any warning. I can try to recreate it sometime, but I'm out of town till next week.

 

[sp4rk]

I'm a little bemused by this thread.

As ... twice now ... I have sat in my car ... after Tesla time outside it, only to be told by Nicola that she cannot find the key in my pocket.

So where is she looking?

Walked away; came back after "out of range" and it works.