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Key Fob draining battery in 20 minutes...

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Head scratcher....
So here's he deal. 4 years in a row.
What happens, overnight, my MX fob battery dies. I replace it, and within 20 minutes, it drains the new battery dead. Replace again, same thing. This happens yearly, almost exactly 1 year, +/- 1 month.
4 years in a row now. First one I had to pay for the replacement given that my 2016 was out of warranty. Second one failed within the 1 year service warranty within 1 week of the 1 year date, so replaced at no charge. Third one failed within 1 year of the second one, about 2 weeks of the 1 year date. I thought maybe it is a Fluke, considering that #3 now lasted past the 1 year mark. But sure enough, got home this evening, went to move the MX out of the driveway so I could back the MS up and unload the trunk into the garage, and the MX not responding. Went in the house grabbed the spare key, started right up. Just checked Fob battery, 0 Volts.
Put a brand new battery in, fob unlocked the car and it started fine, went back in the house. Tried it again 15 minutes later, no response from the car. Checked battery voltage, 0 Volts. Never happens on the Model S.
Now, the first time the fob failed, I started using the spare, and within a week, the spare did the same thing. Both replaced that first time. No fob updates available, and no service warnings any of the failure times.

Didn't mind so much when I didn't need to keep paying for replacements, but any ideas? These things are expensive! No water damage, No physical damage. Even has the sticker on the bottom with the parts number and bar code from the last time it was replaced.
Ideas? The fob, also does not get hot like it would if it was shorting out. Batteries are fresh, I get them from Batteries + Bulbs with my commercial account, and voltage is good before install. Even try them in the spare fob first, leave them for a few hours or even overnight, no problem. Pop it in the failed fob, dead in 20 minutes.
 
Check out this very recent thread: 6 days - that's how long the fob battery lasts

Perhaps try a faraday bag or a Altoid can. I keep a spare when I travel wrapped in tinfoil inside an altoid can in my glove box.
I'm not using the car for camping. Doesn't matter the proximity to the MX. In this instance, used the fob and parked the car in the driveway friday morning, immediately drive the MS 130 miles away. came home Monday night, and immediately upon arrival tried to use it to move the MX back into the street.
Last time it drained like this, I was using the MX.
proximity to the MX doesn't seem to be an issue. Just randomly decides to drain the battery.
 
I'm not using the car for camping. Doesn't matter the proximity to the MX. In this instance, used the fob and parked the car in the driveway friday morning, immediately drive the MS 130 miles away. came home Monday night, and immediately upon arrival tried to use it to move the MX back into the street.
Last time it drained like this, I was using the MX.
proximity to the MX doesn't seem to be an issue. Just randomly decides to drain the battery.
I didn't understand the camping reference or how it came up.

Is your MX fob always keep in the same spot and distance from the MX? If it is always the same and just randomly happens then that is one thing (software issue -- ie. why doing the excess communication or whatever).

I was suggesting you could test with/without the faraday bag or equivalent. Also could take the battery out in those questionable times and test the voltage in or out of the 'faraday' bag. Just a thought.

Re: No water damage, No physical damage. Even has the sticker on the bottom with the parts number and bar code from the last time it was replaced.
Oh, maybe I misunderstood. Are you replacing the fob or battery ... above text sounds like fob
 
I didn't understand the camping reference or how it came up.

Is your MX fob always keep in the same spot and distance from the MX? If it is always the same and just randomly happens then that is one thing (software issue -- ie. why doing the excess communication or whatever).

I was suggesting you could test with/without the faraday bag or equivalent. Also could take the battery out in those questionable times and test the voltage in or out of the 'faraday' bag. Just a thought.

Re: No water damage, No physical damage. Even has the sticker on the bottom with the parts number and bar code from the last time it was replaced.
Oh, maybe I misunderstood. Are you replacing the fob or battery ... above text sounds like fob
That was referring to the link.
The "main" fob stays in my pocket at all times. I mostly drive The MS90D due to longer range VS the mX75D with vastly neutered supercharging speeds, which has mostly become a local only vehicle now due to that.
I attempt to replace the battery, fob keeps draining battery. Over and over and over within about 20 minutes of installation, regaurdless of its proximity to the vehicle. So the fob gets replaced by Tesla and I'm good for another 1 year +/- a month.
 
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I didn't understand the camping reference or how it came up.

Is your MX fob always keep in the same spot and distance from the MX? If it is always the same and just randomly happens then that is one thing (software issue -- ie. why doing the excess communication or whatever).

I was suggesting you could test with/without the faraday bag or equivalent. Also could take the battery out in those questionable times and test the voltage in or out of the 'faraday' bag. Just a thought.

Re: No water damage, No physical damage. Even has the sticker on the bottom with the parts number and bar code from the last time it was replaced.
Oh, maybe I misunderstood. Are you replacing the fob or battery ... above text sounds like fob

Scott - I'm the one using my X for camping, and putting all the keys into the faraday bag at night. Only the single active one has a battery in it that comes out during the day to drive.

I'm starting to think the problem may be on the car side rather than the fob themselves - but still working through it.
 
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Scott - I'm the one using my X for camping, and putting all the keys into the faraday bag at night. Only the single active one has a battery in it that comes out during the day to drive.

I'm starting to think the problem may be on the car side rather than the fob themselves - but still working through it.
Disagree about it being the car side, unless something in the car is triggering the key to self drain. Even when my keys are no where near the car, such as in another city, the MX key will still self drain.
 
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Head scratcher....
So here's he deal. 4 years in a row.
What happens, overnight, my MX fob battery dies. I replace it, and within 20 minutes, it drains the new battery dead. Replace again, same thing. This happens yearly, almost exactly 1 year, +/- 1 month.
4 years in a row now. First one I had to pay for the replacement given that my 2016 was out of warranty. Second one failed within the 1 year service warranty within 1 week of the 1 year date, so replaced at no charge. Third one failed within 1 year of the second one, about 2 weeks of the 1 year date. I thought maybe it is a Fluke, considering that #3 now lasted past the 1 year mark. But sure enough, got home this evening, went to move the MX out of the driveway so I could back the MS up and unload the trunk into the garage, and the MX not responding. Went in the house grabbed the spare key, started right up. Just checked Fob battery, 0 Volts.
Put a brand new battery in, fob unlocked the car and it started fine, went back in the house. Tried it again 15 minutes later, no response from the car. Checked battery voltage, 0 Volts. Never happens on the Model S.
Now, the first time the fob failed, I started using the spare, and within a week, the spare did the same thing. Both replaced that first time. No fob updates available, and no service warnings any of the failure times.

Didn't mind so much when I didn't need to keep paying for replacements, but any ideas? These things are expensive! No water damage, No physical damage. Even has the sticker on the bottom with the parts number and bar code from the last time it was replaced.
Ideas? The fob, also does not get hot like it would if it was shorting out. Batteries are fresh, I get them from Batteries + Bulbs with my commercial account, and voltage is good before install. Even try them in the spare fob first, leave them for a few hours or even overnight, no problem. Pop it in the failed fob, dead in 20 minutes.
Did you figured out what happened? This keeps happening to my 2016MX fob as well. I took my FOB apart and cleaned it, still doing the same thing.