Key fob batteries and air conditioning

[Elkins45]

Recently it’s been difficult to lock my xB using the key transmitter. Oddly it wasn’t difficult to unlock it when I returned after the key had been in my pocket for a few minutes. I was afraid the button was going bad but a little experimentation proved it wasn’t. A fresh battery solved the issue.

I think because it’s been so hot here the transmitter was getting blasted with cold air and it chilled the battery enough that it became too weak to transmit. Once it had warmed up to body temperature in my pocket it had enough juice to send the unlock signal.

 

[Chris142]

I wonder if its a frequency thing? A lower AM frequency will travel farther than a higher AM frequency.

 

[researcher]

Recently it’s been difficult to lock my xB using the key transmitter. Oddly it wasn’t difficult to unlock it when I returned after the key had been in my pocket for a few minutes. I was afraid the button was going bad but a little experimentation proved it wasn’t. A fresh battery solved the issue.

I think because it’s been so hot here the transmitter was getting blasted with cold air and it chilled the battery enough that it became too weak to transmit. Once it had warmed up to body temperature in my pocket it had enough juice to send the unlock signal.

actually those coin cell batteries give more juice when they're warmer. look at any datasheet and you'll see the voltage goes UP when it's warmer, just like body temps! so no, you're not imagining anything, it's a real effect.

it reacts more when the battery is lower in voltage closer to battery's end of life.

 

[opus1]

It makes sense that the cold affected it. A chemical reaction is a chemical reaction, whether it's the coin-cell in a key fob or the 9v battery in the smoke alarm that *always* starts chirping the low battery warning in the early morning, when the house is generally its coolest.