6 days - that's how long the fob battery lasts

[Ostrichsak]

I just got another package of four from Amazon, so I plan to meter these and mark the bags (really kinda sketch packaging on this one, the last batch WERE in Panasonic blister pack, but those were the ones not lasting long. So I want to see where I'm starting from on these.

Read post #2 again as the packaging is irrelevant. If you're not buying directly from the manufacturer's store in Amazon you're not eliminating that potential cause of all of this. The only way to know you're getting authentic batteries is if you see the seller on Amazon is the manufacturer.

 

[jackinbc]

I received my new 2023 Model X Plaid on Sept. 27, 2023 and ordered one fob to start. After it arrived, I got about a week's use out of the fob battery before the battery voltage dropped to 2.90 volts and the fob stopped working. My car is in a building parkade that is 15 storeys away from me, so I wouldn't expect any "constant communication" drain. A Tesla mobile tech dropped by and changed the fob's battery to a new one. The tech mentioned that if the fast-drain happens again, they might try a new fob. Five days later, the fob went dead again with the new battery's voltage measuring lower at 2.53 volts! I've just messaged Tesla service and am waiting for my next mobile service appointment. Until this year, I had a 2018 Model X with two fobs. Each of them only needed one battery change in five years!

 

[ZuleMYP]

Get one of those fob pockets that are a metal (invisible wires) cage.
Put the fob in it while at home. No signals will get into the fob, nor
will it be sending signals. With the fob in its 'pocket' you can take
it right to the car and the car won't 'see' it.

Search for 'key fob protector' and look for the words 'faraday cage'
in the description. I see a usual option is a 2-pack
for around $10.

Just reading this thread and wanted to comment on this OLD comment, but the information needs to be spread... Faraday cages are not just metal enclosures. That actually doesn't stop any RF signals, it just adds more material they have to resonate. Which could actually EAT battery if it's getting through enough to not sleep. A real faraday cage needs to be connected to ground, thus all collected RF energy is sent to ground and does not resonate at all. Not sure if this would help, just wanted to comment.

 

[metroplex]

That's a fair point - but my Model 3 doesn't detect the fob when it is in its faraday pouch. The Bluetooth signal of the fob may be transmitting continuously but wouldn't power consumption be lower if it doesn't connect?

Otherwise I am assuming this is an inherent issue with the use of Bluetooth as a fob signal vice the 450 MHz/ 902 MHz traditionally used in like Ford fob remotes.

I now keep the phone as a key option enabled but don't use it unless I open the app. Makes it convenient to have a key card, phone, and fob as methods of accessing my vehicle.

 

[geordi]

The bluetooth is definitely continuously transmitting, and a Faraday pouch doesn't need to be grounded to block signals - it just has to be of a sufficient mass to drain off the energy within itself. That's the same reason why you can't transmit electrical power through a wire at an infinite distance: It will eventually be drained off by the resistance in the wire mass itself.

I've got a Faraday pouch that I use while car camping and have an Airtag on my keys. When in the bag, the car can't detect the key and the airtag doesn't react / reads as missing.

But as soon as the bag is opened, the car instantly reacts. The fob sucks the battery dry because it is never off.

 

[Silicon Desert]

Not really sure what the problem is, but I feel like it's particular to your car/fob. We have two Model Xs (2017/2018) with a total of four fobs, and I'd say we go a good 2-3 years between battery changes. No special steps taken to preserve battery life.

Yes, we have similar experience. Not sure what the OP's issue is. We have an old MX, a 3 year M3 and 2023 MY with 3 fobs and no such issue. The fobs hang on the wall about 15 feet from the cars. The batteries of the MX and the M3 last average about 18 months. The MY is only a couple months old but so far not an issue with it either.

 

[double07]

I am thinking about getting the key fob for my 23 MXP and this looks like the newer model is behaving differently? I had my 21 MSLR for over three years before trading in for the 23 MXP. During that time of owning the MS, I only had to change the battery once. I guess, I will stick with iPhone key. It has been working just fine. I had issue with phone key once after the SW update. Otherwise, it is great.

 

[geordi]

The key works differently between the model S and the model X. X uses “low energy” Bluetooth, which seems like anything but low energy.

I’m not sure how the proximity system works on the other ones, but they are not transmitting until you are near the car. You are correct, battery life is much better. I have had a couple batteries last longer than a week, but so far the longest is still under one month.

 

[metroplex]

My Ford intelligent access key fobs transmit at 902 MHz and only work in proximity to the car. But I am able to open any of the 4 doors or trunk of my 2017 Fusion Sport by walking up with the fob in my pocket and pushing the trunk button or grabbing the door handle to open. Battery is DL2450 and will easily last 3 years. DL2450 is like the thickness of two CR2032

On the 2022 Tesla Model 3 I can only open my driver door this way. Every other compartment requires the use of the fob or phone. Opening all of the doors requires 4 presses because I have driver door unlock for security reasons. But there’s no reason I need to unlock the entire car to be able to open the trunk via the button on the deck lid. Weird.

 

[jboy210]

I am thinking about getting the key fob for my 23 MXP and this looks like the newer model is behaving differently? I had my 21 MSLR for over three years before trading in for the 23 MXP. During that time of owning the MS, I only had to change the battery once. I guess, I will stick with iPhone key. It has been working just fine. I had issue with phone key once after the SW update. Otherwise, it is great.

My battery lasted about 16 months on the 22 X. I remember replacing the one on my 2018 X about the same age. I sure wish the CR 2354 batteries were easier to find. Took 6 days on Amazon last order.

 

[TOBASH]

Have you checked your vehicle preferences to stop the car from activating when the fob is close-by? I turned all that crap off and I was much happier. I don’t need auto open and auto lights and such. Maybe that coupled with keeping your fob within 20 feet of your car are creating the issue?