pmichaelmd

Anybody else have trouble with a short-lived key fob battery? I have just gotten notification to replace the battery for the second time in five months. Maybe my key sits too close to the vehicle?

Utopia Texas

Out of all the vehicles I have owned over the years MB’s have used up batteries quicker than other brands for some unknown reason. When you replace be sure to buy from a store that sells a lot and you know the batteries don’t sit around too long. I have read horror stories about some Amazon vendors selling very old batteries at really low prices.

hlothery

I've owned my 450 for17 months, have only recently had to replace the battery in the FOB. Replaced with a Duracell from Batterys Plus. Most MB dealers replace the FOB battery with each service visit in my experience.

LasVegas_89135

What replacement battery is required?

Mort

If it the same as previous fobs it is a 2025.

LasVegas_89135

Thank you, my previous car was a Tesla Model S.

superswiss

The battery required is a CR 2032, not 2025. Old batteries that have been sitting on the shelves is not unusual and the most common reason for short battery life. You should actually see increased battery life with the newer fobs, because they have a motion sensor in them and after 2 minutes of not sensing any motion they automatically go to sleep and stop communicating. The primary reason for this is to combat the relay attacks, so nobody can steal your car from your driveway while you are at home, but the nice side effect is that it preserve the battery as well. FWIW, I just recently had to replace the battery in my key fob for the first time after 4 years. It sits at home in sleep mode most of the time as I don't really drive on weekdays.

LasVegas_89135

Thank you the correct information.

Newbyloub

For several years I bought cheaper fob batteries at Radio Shack. Then I realized they were selling old batteries, and now get them at Kroger or Walgreen. Last much longer..

NKPGarage

they're 2032. Just grab a pack on amazon cheap so you have them ready to replace. Personally I would replace them every 4 months in each remote for peace of mind and never have to worry about it.
https://amzn.to/3BXCPyA

W205C43PFL

Just be careful of fake buttons sold as name brands on Amazon, Amazon doesn't validate when seller's stock is just thrown in the genuine stock sometimes.

NKPGarage

good point. Always a good idea to keep an eye on reviews and which seller you’re buying from.

W205C43PFL

Yup, FBA is generally better than just market/third party seller but just worried about Amazon putting fake stock inside the FBA sold by Amazon stock as well. If the market/third party seller is reputable like for example a storefront, or in the case Energizer Official (something like that), it might actually be better than buying from Fulfilled by Amazon sellers or Fulfilled by Amazon sold by Amazon themselves.

NKPGarage

oh, i see what you mean.
So this one would be a safe bet then? Since the actual seller is also Amazon?
https://amzn.to/43v6aMR

W205C43PFL

Yes and no... what I am worried about is that they put other seller's stock (and if it is fake) in the same bin as the one sold directly by Amazon as they don't verify if they are genuine before tossing it in.

Utopia Texas

Just go to your local grocery store or Walmart where they sell a lot of batteries and you know they will be fresh. Saving 25 cents on a iffy battery from Amazon for a 100k automobile makes no sense….

W205C43PFL

I guess this as well, maybe Amazon is about the convenient assuming those who work at home and order groceries online now, dang things really changed us these couple of years. I got so lazy now.

c4004matic

The battery on mine is doing fine after 14 mths. The issue is that the fob goes to sleep. If its been sitting inside the car overnight, it needs a little jiggle to wake up.

hlothery

Sounds like me in the morning......just sayin'

W205C43PFL

and... me as well

LasVegas_89135

Can the car detect whether the fob battery is running low and give a warning?

c4004matic

I think so.....

superswiss

Yes

W205C43PFL

Except the key fob always dies before the warning comes up for me for some reason , ymmv.

hlothery

The car does warn you, and I have learned the hard way not to ignore that warning for more than a few days!