Life expectancy of car key batteries

manfromwahoo

New member
We've had our coach since the end of June 2015. The third set of CR2025s batteries is now needed on my key set. That's only about 2 months. The wife's set is still good. Anyone had this issue? Thanks.
 

avanti

2022 Ford Transit 3500
I have never had a fob battery on any vehicle last less than 5 years. Perhaps a button is being held down by pressure in your pocket?
 

peteaeonix

New member
I replaced the batteries in the Key fob(s) after about 5 years based on the year of the chassis (e.g. I have a 2010 chassis in a 2011 Roadtrek). There is a way to "test" the battery (see the Sprinter Owner's manual) and if the led doesn't turn on during the test, then it's time to change the battery.

I note that I have multiple keys (for different vehicles) with door and trunk lock controls built in. I discovered that when sitting at a computer (or at the dining table) that random variations can cause pressure on the buttons. I discovered this when I found my Toyota's trunk open in the garage ... and the battery dead (in the car) as it had sat for several days with the light in the trunk shining... (I work at home, and thus did not take the car out for several days.) I then installed a set of hooks by the door to the garage, where I now store my vehicle keys.

On a subsequent occasion, I had forgotten to hang up the key, and through random luck, pressure on the buttons set off the "alarm" system in the car. It was a good lesson ... and I'm now much better at remembering to hang up my keys.

So, yes, pocket pressure on the buttons can easily run down the battery in the fob...

As for "AAAdventuremotovan" ... might be a warranty issue...
 

manfromwahoo

New member
4 sets of batteries now in less than 8 months. I've tried everything recommended and it's only getting worse. The keys can be just laying there on the kitchen counter with no pressure on the buttons and suddenly the door locks will pop. Clearly something wrong with the contacts inside the fob. I called a MB dealer in Corpus Christi and was told that before I could assert a warranty claim, I'd have to document buying the batteries from a MB dealer. Fortunately, no trouble with the wife's key fob. I'll wait until the batteries fail again and then buy them from MB.... probably big bucks but I'll bet that it'll be energizers from them also.
 

manfromwahoo

New member
The MN RT dealer claimed to have fixed the key fob on at least 3 occasions. Each time, the batteries went dead within about 5 weeks. I had to escalate to MB and after MUCH conversation, and 2 trips to Freightliner (quaified service center) they finally came thru with a new key fob on their 'such as it is' warranty. It's been 2 months now and it's still working. I've learned not to hold my breath on these warranty issues.
 

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