Key FOB Battery Life
Thread Starter
Newbie
Joined: Jun 2012
Posts: 11
Likes: 0
From: LI NY
Audi S5
Key FOB Battery Life
I think I'm having issues with my remotes. I have the keyless go option. I changed the batteries in both remotes and they both lasted 3-4 months each.
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
MBWorld Fanatic!
Joined: Mar 2007
Posts: 1,146
Likes: 9
From: Vancouver, BC
2015 E250 BT 4M
key batteries
I think I'm having issues with my remotes. I have the keyless go option. I changed the batteries in both remotes and they both lasted 3-4 months each.
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
As for battery life, based on my previous 2013 E350BT, I would say 6-12 months.
The current Smart Keys only have one battery, whereas previous versions had a pair. Maybe this change shortens the service life of the battery ?
I suspect that the Smart keys are produced well before the car is built or the installed batteries are not fresh ?
Last edited by DerekACS; Jan 4, 2015 at 09:29 PM.
Senior Member
Joined: Mar 2014
Posts: 282
Likes: 5
From: in these United States
'10 W212 4matic P2-Distronic / '14 Cayenne / '04 X5 3.0 / '13 Altima
yes mine only last that long too. I think it maybe because my keys are so close to the garage as another previous poster suggested, but I haven't bothered to put them somewhere else. I just bought a lot of batteries from Amazon.com for not much money compared to the store
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MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
My first set lasted 6 months, second set lasted 4 months, 3rd set lasted 6 months, 4th set lasted 2 months, on my 5th set now and it's been 2 months. Got the replace key battery warning last week. I removed the battery in the key, re-inserted the battery and the warning went away and hasn't come back in a week.
I keep my key on a shelf next to the door to the garage so it's about 15 ft away from the car. That may be draining it faster than usual. My other key sits in a safe on the other side of the house. Out of curiosity I tried it today and it didn't get the replace battery warning. It has been sitting in that safe since I got the car 20+ months ago.
I bought a 20 pack of sony batteries off ebay for like $5 so it doesn't bother me to have to replace the battery every few months. It's a quick and simple process and I always get a couple weeks warning on the dash before the key actually stops working (replace key battery will pop up a few weeks before the battery is completely dead).
I keep my key on a shelf next to the door to the garage so it's about 15 ft away from the car. That may be draining it faster than usual. My other key sits in a safe on the other side of the house. Out of curiosity I tried it today and it didn't get the replace battery warning. It has been sitting in that safe since I got the car 20+ months ago.
I bought a 20 pack of sony batteries off ebay for like $5 so it doesn't bother me to have to replace the battery every few months. It's a quick and simple process and I always get a couple weeks warning on the dash before the key actually stops working (replace key battery will pop up a few weeks before the battery is completely dead).
MBWorld Fanatic!
Joined: Aug 2004
Posts: 1,367
Likes: 3
From: MA
'24 Porsche Macan
Last BMW (which also had keyless go) were two years and still going strong. I see my supply of CR2032 computer motherboard batteries won't do, since the Benz uses CR2025. Glad I saw this thread. I'll be ordering some.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
Actually CR2032 will fit the MB key. difference between 2025 and 2032 is one is 2.5mm thick while the other is 3.2mm thick.
2032 also has more power. Both are 3V, but 2025 is about 150mah while 2032 is about 200 to 225mah so close to a 50% increase in power.
It takes a little bit of pressure to push a 2032 into the battery compartment of the key but it does work. (tested it myself).
I'm actually using 2032's now in my key since I work in IT, do a lot of computer work and thus buy and use a lot of 2032 batteries.
MBWorld Fanatic!
Joined: Apr 2013
Posts: 1,506
Likes: 66
From: Sidney, BC
2009 SLK55 AMG. & 2022 GLA250 4Matic
Keyless Go
I think I'm having issues with my remotes. I have the keyless go option. I changed the batteries in both remotes and they both lasted 3-4 months each.
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
How long do your batteries last?
Sometimes the car says key not detected when I hit the button to start and then eventually starts. Also says it while I'm driving the car, the message will suddenly appear. I just changed the battery last week. The problem is Intermittent so it would be difficult for the dealer to recreate.
Anyone have this issue?
The 2011 W212 with Keyless Go goes through batteries about 4-5 months.
Pissed my dealer off during a service event when they changed the battery, charged $15 for it and charged 15 minutes labour.
Took it out, gave it back to them and told them to redo the bill.
I buy multiples at Walmart to cover 9-12 months.
Thread Starter
Newbie
Joined: Jun 2012
Posts: 11
Likes: 0
From: LI NY
Audi S5
Thanks for the replies, i am suprised they dont last that long my audi and bmw keys just 1 of them lasted longer than both my merc keys.
I agree the batteries are cheap and i ordered alot of them i was just concerned that the fobs were about to fail and my warranty expires soon
I agree the batteries are cheap and i ordered alot of them i was just concerned that the fobs were about to fail and my warranty expires soon
Junior Member
Joined: Feb 2009
Posts: 28
Likes: 0
From: Madison, WI
'12 E350 4Matic, '11 GLK350 4Matic
I am having the same problem. In 6 months I have replaced the battery twice. The last one lasted maybe 4 weeks. I got the message Yesterday. My keys are about 20 feet from the car. Does that make a difference? 
My car has Keyless Go
My car has Keyless Go
Last edited by andre2p; Jan 7, 2015 at 03:24 PM. Reason: more info.
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? I've gone 4+ years in non keyless go cars but never more than 6 months in keyless go equipped cars.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
I think by keeping the key close to the car, something with the keyless go system is constantly communicating with the key thus draining the battery quicker. (just a theory).
Senior Member
Joined: Apr 2004
Posts: 254
Likes: 4
From: N. Illinois, USA
2021 GLS450, 2015 E250BT 4Matic, 2007 GL320CDI, 2005 SLK350, 2001 SLK320
This is surprising. Our 2007 GL320 has keyless go and we're only on our second battery. We hang the key about 40 feet away from the car, if that matters. I also have a Ford Explorer with Ford's version of keyless-go. The key is also stored about 40 feet away from the car. I'm still on the original battery after 3 1/2 years. Maybe we're just lucky?
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,283
Likes: 126
From: Central Coast, CA
2020 X7 xDrive40i, 2016 X3 sDrive28i
This is surprising. Our 2007 GL320 has keyless go and we're only on our second battery. We hang the key about 40 feet away from the car, if that matters. I also have a Ford Explorer with Ford's version of keyless-go. The key is also stored about 40 feet away from the car. I'm still on the original battery after 3 1/2 years. Maybe we're just lucky?
MBWorld Fanatic!
Joined: Jul 2002
Posts: 2,677
Likes: 3
From: California
i535
I noticed I get shorter battery life when buttons get accidently pressed by other keys in pocket. I several time noticed my trunk is open.
If you just commute and not so far then battery life is over 24 months.
If you just commute and not so far then battery life is over 24 months.
Junior Member
Joined: Nov 2013
Posts: 45
Likes: 0
From: Virginia Beach
2011 SL550
Key FOB Battery Life
I bought a CPO 2012 SL550 last year. Leave one in console (start & go) and is still going strong. Other one is in den (spare key drawer) same length of time. Just tested so working fine. I doubt if replacing batteries in key fob is part of CPO so maybe the fobs use less power?
MBWorld Fanatic!
Joined: Nov 2009
Posts: 2,616
Likes: 160
From: Southeastern USA
2010 E350 Luxury Sedan, Engine 272 (V6)
I have 2010 with Oct. 2009 build date without keyless go, just the "Smart Key." Both fobs were still working fine, but I replaced the battery in main one last week just to be safe. Will replace the other one eventually, but I only use it for dealership servicing.
I lock my car every time I get out, even when in my garage.
Real simple and batteries costs about $6.00 for a pair. Will keep the old ones in the trunk probably.
I lock my car every time I get out, even when in my garage.
Real simple and batteries costs about $6.00 for a pair. Will keep the old ones in the trunk probably.
MBWorld Fanatic!
Joined: Jul 2002
Posts: 2,677
Likes: 3
From: California
i535
if you do not have keyless go feature, then you may never replace batteries. If battery goes completely down (Usually 5-6years), you will still able to start car, you lose only ability locking doors remotely. Not a big deal in my opinion.
Keyless go drains battery in 18 months in my experience. I was in situation when a battery has completely gone couple time. You need to pull mechanical key to unlock door and insert plastic part in ignition to start car. A bit inconvenient but again not big deal. Much worse situation if you won Lexus and your key battery has gone
Keyless go drains battery in 18 months in my experience. I was in situation when a battery has completely gone couple time. You need to pull mechanical key to unlock door and insert plastic part in ignition to start car. A bit inconvenient but again not big deal. Much worse situation if you won Lexus and your key battery has gone
