Opening the doors and starting the car with a dead keyfob battery

AllenWong · Mar 17, 2015

I have a P85D and I can't open the door or start the car when the keyfob has no batteries or has dead batteries. I read in the manual that I could put it on the passenger side windshield to open the door. I also read that you could put the key in the cup holder or near the charge port to start the car. Neither of these features worked for me. I am worried that one day my batteries would die and I'd be stuck in the middle of nowhere. Has anyone successfully opened their doors/start their car with the battery out of their keyfobs?

toolmanca1 · Mar 17, 2015

I don't have a keyfob way to do it, but I have opened the doors and driven the car, with no keyfob, using the app on my phone. That is my backup to a keyfob that is dead.

Dave

mknox · Mar 17, 2015

The locations Tesla recommends are near the antennae and will work with a weak battery but not with a dead battery (or no battery) . There is no RFID chip or similar contrary to the belief of some. You can test this for yourself like I did by removing the battery. You cannot get in to or operate the car with no battery but as @toolmanca1 says, you can use the mobile app.

redox · Mar 17, 2015

Is there a low battery indicator somewhere to give you a bit of heads up?
I'd hate to be locked out without warning in an area with no cell/wifi coverage (so no way to use the phone app workaround).

I wish they'd implement some of this functionality through the bluetooth pairing so it works even without cell/wifi coverage, just with the phone within bluetooth range.

saladman · Mar 17, 2015

Low tech solution:

Hide a spare fob battery behind the nose cone. Pop it in during a crisis. Similar to surfers, and the padlock box off the tow hook with the car key.

PaulusdB · Mar 17, 2015

Low tech, but practical solution:

Put a spare fob battery in your silicone fob pocket, together with the fob.

vgrinshpun · Mar 17, 2015

regoapps said:
I have a P85D and I can't open the door or start the car when the keyfob has no batteries or has dead batteries. I read in the manual that I could put it on the passenger side windshield to open the door. I also read that you could put the key in the cup holder or near the charge port to start the car. Neither of these features worked for me. I am worried that one day my batteries would die and I'd be stuck in the middle of nowhere. Has anyone successfully opened their doors/start their car with the battery out of their keyfobs?

The chances that the keyfob battery will die are very slim - these batteries are replaced every year/12,500 miles as part of the annual service.

SummerlinModelS · Mar 17, 2015

redox said:
Is there a low battery indicator somewhere to give you a bit of heads up?
I'd hate to be locked out without warning in an area with no cell/wifi coverage (so no way to use the phone app workaround).

I wish they'd implement some of this functionality through the bluetooth pairing so it works even without cell/wifi coverage, just with the phone within bluetooth range.

I did get a warning message that my battery was low. I popped over the Home Depot and bought a two-pack and replaced both batteries at the same time (this was after 11 months of ownership). The next month when the car was in for it's annual they replaced the battery automatically.

AoneOne · Mar 17, 2015

Last year I tried removing the battery from my fob and, while I could not unlock the car with it, I was able to start the car by holding the fob near the USB and 12-V connectors below the armrests.

deonb · Mar 17, 2015

SummerlinModelS said:
I did get a warning message that my battery was low. I popped over the Home Depot and bought a two-pack and replaced both batteries at the same time (this was after 11 months of ownership). The next month when the car was in for it's annual they replaced the battery automatically.

Interesting. Where? Does the car notify you on the console?

mknox · Mar 18, 2015

deonb said:
Interesting. Where? Does the car notify you on the console?

My last car would warn of a low fob battery but I have not seen it in the Model S (yet). I have seen "Fob not Detected" messages and tracked it down to interference from my cell phone in the same pants pocket.

jhs_7645 · Mar 18, 2015

To the original poster. Did you consider what @toolmanca1 said? Seems to me that the phone app is the best backup of all.

dave · Mar 18, 2015

Don't want to go off topic, but someone asked me the other day how I'd get in the car if the battery was dead (car battery, not FOB). I didn't know what to tell him! Do the door handles still pop out, or is there a manual way to get in the car?

PaulW5 · Mar 18, 2015

mknox said:
My last car would warn of a low fob battery but I have not seen it in the Model S (yet). I have seen "Fob not Detected" messages and tracked it down to interference from my cell phone in the same pants pocket.

Model s Will warn you with a warning in both screens when key fob battery is low.

austinEV · Mar 18, 2015

dave said:
Don't want to go off topic, but someone asked me the other day how I'd get in the car if the battery was dead (car battery, not FOB). I didn't know what to tell him! Do the door handles still pop out, or is there a manual way to get in the car?

Which battery? the car has the main giant skateboard battery, and a small 12V battery like for a motorcycle under the hood. If the main battery is at zero miles, the car's functions will still work for a long time because the 12V system is up. If the 12V battery is dead you have big problems and a dead car. No the doors won't open. You have to attach a 12V source to the terminals under the nose cone to fire up the car's systems.

dave · Mar 18, 2015

That's what I figured. Any other cars out there other than Tesla that require the 12V battery to open the doors?

AllenWong · Mar 19, 2015

austinEV said:
Which battery? the car has the main giant skateboard battery, and a small 12V battery like for a motorcycle under the hood. If the main battery is at zero miles, the car's functions will still work for a long time because the 12V system is up. If the 12V battery is dead you have big problems and a dead car. No the doors won't open. You have to attach a 12V source to the terminals under the nose cone to fire up the car's systems.

And if you're still inside the car while the battery is dead, you're still okay, because there's a manual unlock inside the front doors' handles. The manual unlock for the back doors are near the front of the back seat where your legs dangle.

Thanks for letting me know that the keyfob cannot unlock the car with dead battery. I thought my car are defective.

And yes, the iPhone app is my best bet. It's just that sometimes I keep the iPhone inside the car (like when I go swimming at the beach). That's the other reason why I'm asking. If my keyfob drops into water, it'd die (or at least fry the battery). Without some way to open the door without a battery, I'd be screwed.

I like the idea of hiding a spare battery in the nose cone. But don't you need to open the front trunk to pop out the front nose cone?

mknox · Mar 19, 2015

PaulW5 said:
Model s Will warn you with a warning in both screens when key fob battery is low.

Has anybody actually seen the message? I've tried removing the battery and all I get is a "Keyfob not Detected" message, but maybe it has to see a weak signal to trigger the low battery one.

- - - Updated - - -

dave said:
That's what I figured. Any other cars out there other than Tesla that require the 12V battery to open the doors?

My last car, a Cadillac CTS also had solenoid operated doors and a proximity keyfob like the Model S. What was interesting about that car was that there was an old-style metal key hidden in the fob for emergencies, but when I tried using the key, it didn't actually unlock the door mechanically. When I turned the key, it would activate the solenoid and the door would pop open just as if I'd used the handle. To me, that meant the mechanical key would be useless if the car's 12v battery was dead.

dave · Mar 19, 2015

I thought I'd add that Tesla can unlock the doors remotely if you call them. Don't ask how I know this.

FlasherZ · Mar 19, 2015

mknox said:
Has anybody actually seen the message? I've tried removing the battery and all I get is a "Keyfob not Detected" message, but maybe it has to see a weak signal to trigger the low battery one.

Yes, I've gotten it a couple of times.

My last car, a Cadillac CTS also had solenoid operated doors and a proximity keyfob like the Model S. What was interesting about that car was that there was an old-style metal key hidden in the fob for emergencies, but when I tried using the key, it didn't actually unlock the door mechanically. When I turned the key, it would activate the solenoid and the door would pop open just as if I'd used the handle. To me, that meant the mechanical key would be useless if the car's 12v battery was dead.

Yes, there are several newer cars that use electric door releases and would have the same situation.

Opening the doors and starting the car with a dead keyfob battery

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