Both key fobs on low battery after 8 months?!
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Junior Member
Joined: Jan 2015
Posts: 22
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From: UK
C250(W205)
Both key fobs on low battery after 8 months?!
So my car started to alert me saying that my key had low battery. So I switched to my spare. A few months in, it's started to do the same. I don't understand how my previous BMW didn't require a battery change in 7 years but my two MB keys won't last 4 months each. I place my keys around 4 metres from my car overnight so I can't imagine it's being drained by the car. Also I only drive around 20 minutes a day. Anyone else had this issue? Could this be a fault or is it a common thing?
Junior Member
Joined: Jun 2010
Posts: 53
Likes: 10
w205
So my car started to alert me saying that my key had low battery. So I switched to my spare. A few months in, it's started to do the same. I don't understand how my previous BMW didn't require a battery change in 7 years but my two MB keys won't last 4 months each. I place my keys around 4 metres from my car overnight so I can't imagine it's being drained by the car. Also I only drive around 20 minutes a day. Anyone else had this issue? Could this be a fault or is it a common thing?
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
Do you have keyless go? If you do and you keep your keys close enough to the car (20 to 30 ft) it will constantly communicate with the car and drain the battery very quickly.
your BMW likely didn't have keyless go (or whatever BMW calls it) thus the battery lasted 7 years.
My previous BMW key battery lasted 8 years 175k miles. My current E350 key lasts about 2 to 3 months with the standard CR2025 battery, or more than 8 months with a slightly thicker CR2032 battery. I keep my key about 10 to 15 ft away from the car.
My spare key is on the other side of the house away from the car and it is still on original battery after nearly 3 years. I use the spare about once every 2 or 3 months.
your BMW likely didn't have keyless go (or whatever BMW calls it) thus the battery lasted 7 years.
My previous BMW key battery lasted 8 years 175k miles. My current E350 key lasts about 2 to 3 months with the standard CR2025 battery, or more than 8 months with a slightly thicker CR2032 battery. I keep my key about 10 to 15 ft away from the car.
My spare key is on the other side of the house away from the car and it is still on original battery after nearly 3 years. I use the spare about once every 2 or 3 months.
Junior Member
Joined: Aug 2014
Posts: 31
Likes: 0
From: Brisbane, Australia
X253 GLC63S
Yep keyless go
I keep my keys in the house 1 floor above so it's not close enough
I'd say they have had the fobs in stock for some time or used some cheap battery supplier
I keep my keys in the house 1 floor above so it's not close enough
I'd say they have had the fobs in stock for some time or used some cheap battery supplier
Do you have keyless go? If you do and you keep your keys close enough to the car (20 to 30 ft) it will constantly communicate with the car and drain the battery very quickly.
your BMW likely didn't have keyless go (or whatever BMW calls it) thus the battery lasted 7 years.
My previous BMW key battery lasted 8 years 175k miles. My current E350 key lasts about 2 to 3 months with the standard CR2025 battery, or more than 8 months with a slightly thicker CR2032 battery. I keep my key about 10 to 15 ft away from the car.
My spare key is on the other side of the house away from the car and it is still on original battery after nearly 3 years. I use the spare about once every 2 or 3 months.
your BMW likely didn't have keyless go (or whatever BMW calls it) thus the battery lasted 7 years.
My previous BMW key battery lasted 8 years 175k miles. My current E350 key lasts about 2 to 3 months with the standard CR2025 battery, or more than 8 months with a slightly thicker CR2032 battery. I keep my key about 10 to 15 ft away from the car.
My spare key is on the other side of the house away from the car and it is still on original battery after nearly 3 years. I use the spare about once every 2 or 3 months.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
I don't know about cheap batteries, I've tried several different brands of name brand CR2025 batteries, they all die after about 2 to 3 months.
The "cheap" battery that came with my 2nd key fob that I keep on the other side of the house is still fine after nearly 3 years.
The last battery I put in my main fob is a "cheap" ebay battery that came from china and was $5 for 25 batteries. I bought the thicker CR2032 and so far it has been fine after 8 months.
The "cheap" battery that came with my 2nd key fob that I keep on the other side of the house is still fine after nearly 3 years.
The last battery I put in my main fob is a "cheap" ebay battery that came from china and was $5 for 25 batteries. I bought the thicker CR2032 and so far it has been fine after 8 months.
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Member
Joined: Dec 2014
Posts: 109
Likes: 6
2015 c300
So my car started to alert me saying that my key had low battery. So I switched to my spare. A few months in, it's started to do the same. I don't understand how my previous BMW didn't require a battery change in 7 years but my two MB keys won't last 4 months each. I place my keys around 4 metres from my car overnight so I can't imagine it's being drained by the car. Also I only drive around 20 minutes a day. Anyone else had this issue? Could this be a fault or is it a common thing?
Junior Member
Joined: Aug 2015
Posts: 29
Likes: 0
From: Cincinnati
MB C450 (soon)
One floor above is probably still too close. It was for my Audi A4. Drained both fobs. Even the one I wasn't using. You can check by pushing panic button from where you keep keys and see if it activates.
Newbie
Joined: Oct 2015
Posts: 7
Likes: 0
From: South West
2015 C220 Bluetec Sport Premium estate
You can turn off the keyless go communication on the key - double press of the lock button should do it. This will save the battery for your spare key. When you want use it, just press the unlock button, and it's all turned back on.
Junior Member
Joined: Sep 2011
Posts: 22
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1998SLK230, 2015 C300 4Matic
Fob battery @5 months. Guess I can park around block...
MBWorld Fanatic!
Joined: Sep 2014
Posts: 1,822
Likes: 33
From: Whitefield, NH
2015 C300 Sport: Palladium, Premium, Multimedia, Leather, BLIS
I wonder if this is the cause of so many "keyless go doesn't work intermittently" problems. Reach in to your pocket and double tap the lock button on the fob, now the next time you walk up to the car it pretends it doesn't know who you are and won't open the doors.
Fob battery @5 months. Guess I can park around block...
Fob battery @5 months. Guess I can park around block...
Junior Member
Joined: Sep 2011
Posts: 22
Likes: 0
1998SLK230, 2015 C300 4Matic
I found this on cars.com long term test drive for the c300:
"Our dealership's service consultant said something went corrupt in the module, so a technician flashed the control unit with the latest software and we were back in business. The update was covered by our warranty. A few thousand miles later and we're still in good shape with a functioning Keyless-Go system"
https://www.cars.com/articles/would-...1420682915840/
"Our dealership's service consultant said something went corrupt in the module, so a technician flashed the control unit with the latest software and we were back in business. The update was covered by our warranty. A few thousand miles later and we're still in good shape with a functioning Keyless-Go system"
https://www.cars.com/articles/would-...1420682915840/
Senior Member
Joined: Jan 2016
Posts: 276
Likes: 21
C350e
Single click on one of the buttons and the keyless is enabled again.
MBWorld Fanatic!
Joined: Nov 2012
Posts: 6,130
Likes: 1,117
A gaggle of MB's
I understand the frustration -tMercedes uses Panasonic (good brand) who moved their battery factory from Japan to Indonesia about 6 yrs ago.
Since that move to Indonesia - the Panasonic Indonesia battery has had sh*tty life - and there have been all sortof bullsh*t "stories" that have developed over recent years about why the Keyless Fob's go thru these "bad batteries" so often.
The problem goes away by switching to genuine Maxell CR2025 - new E-Class/S-Class fob's CR2032 different size - the genuine Maxell is sold ONLY in "hologram" package - believe it or not this button battery business is fill with counterfeit brands.
A 5-pack - and Maxell CR2025's have a 6 yr shelf life - is Amazon like $3 - on my side I have our dealership buy in 1,000 lots for like $.37 each and have tech's and sales replace ALL new and used MB key fob's with ONLY Maxell - and we eliminated this little nasty problem:
Since that move to Indonesia - the Panasonic Indonesia battery has had sh*tty life - and there have been all sortof bullsh*t "stories" that have developed over recent years about why the Keyless Fob's go thru these "bad batteries" so often.
The problem goes away by switching to genuine Maxell CR2025 - new E-Class/S-Class fob's CR2032 different size - the genuine Maxell is sold ONLY in "hologram" package - believe it or not this button battery business is fill with counterfeit brands.
A 5-pack - and Maxell CR2025's have a 6 yr shelf life - is Amazon like $3 - on my side I have our dealership buy in 1,000 lots for like $.37 each and have tech's and sales replace ALL new and used MB key fob's with ONLY Maxell - and we eliminated this little nasty problem:
