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Even when I use new batteries, it isn’t long before my dash says, “Replace Key Battery.”
I’ve noticed that when I insert a new CR2025 battery, I push it in all the way, thinking that the rubber “D” shaped ring on the cover will continue to push the battery down for good contact. Later, when I get the dash error, I remove the battery cover and see that the battery is not all the way in where it should be. I’ve concluded the D-ring is not always doing its job. Maybe the rubber dries out with age?
So, I cut a cross section of jelly fishing lure into a slice about 1/8” thick (+/-) and placed it within the D-ring. The jelly is very pliable, and I figure it will conform between the cover and battery face and press it down. And… it works!!!
You will have to shape the jelly wedge with scissors to get the battery cover to install flush with the fob. (The wedge is thinner facing the outer edge and thicker toward the center of the cover.)
I hear rustling sounds of peeps headed to the fishing tackle box…
I still get well over a year on my fob batteries. Well, the dealer replaces them every year and I never touch it in between annual services. How often do yours crap out?
In any event, you always have creative ideas, I must admit!
My first two years of ownership, the batteries lasted like yours. It's only been in the last 3-6 months that I've been getting the error message. Don't know why, as I keep the keys inside the house at reasonable temps.
My first two years of ownership, the batteries lasted like yours. It's only been in the last 3-6 months that I've been getting the error message. Don't know why, as I keep the keys inside the house at reasonable temps.
Couple times had the experience of replacing the keyfob cell to get greated shortly after again with a "low keyfob battery" reminder.
upgraded size
My first reaction was to upgrade cr2025 to one size up cr2032... it fits like a glove but that's only a bandaid on a wooden leg...
Steps towards a fix:
They are other reasons KeylessGo can get restless (incompatible DCU Firmware, loose connector pins,..) and cause keyfob drain.
I'd scan the car to see what other errors are found on CAN-B (doors, tpms,...) then do a battery reset to get ECU and friends back on their best behavior.
Lastly I'd look through published TSB'S fixes for those applicable to your car issues.
My CR2032 has been fine well over 3 years.
Hope you find relief.
Last edited by CaliBenzDriver; 09-26-2021 at 01:39 PM.
Reason: steps for relief
What a creative way of cancelling that message
I remember using 2032 when I had to replace the batteries as well. 2032s seem to have a longer life over 2025s from what I see
CR2032 will not fit in my key fob without forcing it in place. CR2025 and CR2032 both measure 1.785" in diameter. So I presume the extra thickness makes the 2032 such a tighter fit. But the cover bends over the fatter battery, sometimes making it difficult to latch the cover in place.
Once jammed in place, it will not move, which I suppose avoids the loose fit problem. But then, to change it later, you have to gently pick it out with a tool that doesn't scratch anything..
My first two years of ownership, the batteries lasted like yours. It's only been in the last 3-6 months that I've been getting the error message. Don't know why, as I keep the keys inside the house at reasonable temps.
Are you using fresh batteries when you replace? Perhaps you bought a 5-pack of them and when you get to the last two or three of them they could be well below fresh battery charge. This has happened to me so I don’t buy multiple batteries anymore. Maybe just a double pack to have one spare.
These button batteries seem not hold charge unused like the rod batteries do.
I also use CR2032. It fits tight but to get it out a tip of a knife or a small screw driver is needed.
I use fresh batteries as you do. I also test them when new with a top-shelf Battery Multi-Tester I have used for many years.
The thicker CR2032 battery means that the rubber D in the cover can push it further into the cavity (if the press fit doesn't jam it in place). If you can push the cover over a CR2032 and it closes flush, just imagine the gap in there with the thinner CR2025, allowing it to move around.
My concern with the CR2032 is that bending over the thicker battery, the cover doesn't snap securely in place as it does with the thinner CR2025. I have to fiddle with the cover on mine several times to make them latch. Have any of you lost the cover?
The upshot of this thread is that when you get the "Replace Key Battery" message with a CR2025 in place, you can install the fishing lure jelly... and the message goes away. Can't see instantly better results than that.
I will see in time how much more use I get until the message returns (a legitimately low battery).
I think I am on 3rd year on my battery, but
- I never push remote buttons, only use door handles for locking/unlocking
- as soon as I enter the house, the key goes into kitchen drawer, so it is not subject to moving, what suppose to keep it active
-we drive the car about twice a week.
I think I am on 3rd year on my battery, but
- I never push remote buttons, only use door handles for locking/unlocking
- as soon as I enter the house, the key goes into kitchen drawer, so it is not subject to moving, what suppose to keep it active
-we drive the car about twice a week.
Just for contrast, the key fobs on my 2001 C320 are not Keyless Go, so we use the buttons constantly. The kicker is that I have needed to replace their CR2025 batteries no more than twice each in 20 years.
Edit: I have changed the C320's batteries so seldom that I forgot (until I just looked) that those fobs contain two CR2025s each (6V).
if you double click the 'lock' button on the fob, the tiny LED on it does a double blink, and the fob switches completely off. I do this any time I'm not going to be using the car for a few days, I'm sure it saves fob battery life. press any button to turn the fob back on.
no, I don't believe they are motion sensing, they listen for RF pings from the car
if you double click the 'lock' button on the fob, the tiny LED on it does a double blink, and the fob switches completely off. I do this any time I'm not going to be using the car for a few days, I'm sure it saves fob battery life. press any button to turn the fob back on.
no, I don't believe they are motion sensing, they listen for RF pings from the car
Does not work on my 2014 E, nor on 2016 GLE.
Never got double blink and the key is still active.
Now would the key stay active waiting for pings, wouldn't the battery discharge in less than 2 years just from that?
I just replaced batteries on my house wind sensor. They lasted 3 years, being constantly active, but they were 2 of C-size batteries, so huge comparing to what we have in keys.
if you double click the 'lock' button on the fob, the tiny LED on it does a double blink, and the fob switches completely off. I do this any time I'm not going to be using the car for a few days, I'm sure it saves fob battery life. press any button to turn the fob back on.
no, I don't believe they are motion sensing, they listen for RF pings from the car
Does not work on my 2014 E, nor on 2016 GLE.
Never got double blink and the key is still active.
Now would the key stay active waiting for pings, wouldn't the battery discharge in less than 2 years just from that?
Krzysztof. you have to double click the button very quickly, like within 1/3 second, to get the double blink... It takes some practice every time I do it, but it works. Try some more.
Krzysztof. you have to double click the button very quickly, like within 1/3 second, to get the double blink... It takes some practice every time I do it, but it works. Try some more.
That worked on my 2016, but not on 2014, even I have the blinks now.
EDIT konigstiger posted at the same time and it confirms
09-25-2021, 07:56 PM
Simple Fix for “Replace Key Battery”
