jahquan3

Does anyone know the battery # or type I need to replace? Also I don't see a screw or latch to open it when I change it. I tried searching but I end up in other portions of forum without a clear answer. This is for a 2010 E550 with Keyless Go.
Thx

Plutoe

Find a Radio Shack or simular and watch him open the fob!!

KEY08

Page 317 in the manual. Got one of those? LOL
CR2025 Lithium battery. Pull the steel key out and stab the inside of the key adjacent to the slot the steel key fits into. The top will pop open and expose the battery. Replace it and snap the cover back on.

jahquan3

Lol. Yes I do but it's stored on my work computer and I'm off today. I don't have a physical copy. Thx for the help I figured I'd get help here and avoid logging into the VPN.

lawguy

They sell in packs of 1, 2 and 4 at Home Depot.

jahquan3

Thx, appreciate the help. I have a Walgreens close with an isle of various batteries. I'm going to check there first and look into your suggestion next if they don't carry it.

KEY08

Walgreens carries them. That is where I always buy mine. 2-pack

rediesel

Glad you've found your way over to the W212 forum; I've missed your post since I departed the W211 arena.


OP they alos sell 2 packs at Advance and other auto stores as well. CR2025 is what we need.

Johnny Rad

Consider putting an extra battery in your glove box for "next time."

Buying batts online through Amazon or flebay can be considerably less expensive than local brick and mortar stores, but rumor has it there are lots of old and no-name batts online. The cheapies have always worked fine for me. YMMV.

jahquan3

Thank you this is very helpful. Thanks everyone else as well. I'm on the mobile site but once I get on PC I'll add some tags to aid in a search if it allows for future reference.

jahquan3

I ended up finding them at W algreens. I bought a pack of two priced at 7.29 . I replaced it and will leave the extra in the glove. Good looks (Thx) to everyone for the swift help.

KEY08

I usually get about a year out of mine and I have Keyless Go like you. Some get considerably less than that and I'm not sure why. I drive my car every day of the week.

jahquan3

One thing that did come up when I searched the forum, was the life span of these batteries. Most people seem to say they last in the 6 months to a year range. There were some theories about placement of the FOB at night nearby the vehicle. Their theory was that the FOB constantly communicates with the vehicle if it is in a certain proximity to it.
I didn't see factual proof but many seem to believe that putting it far away at night would extend the batteries life.

lawguy

My SA said that the keyfob is often emitting a signal, looking for the car (or something like that) which was interesting to me, and explains why it doesnt last as long as some of my other keyfob batteries have in the past. But at $9 for four, I aint complainin'.

jahquan3

Ah....Home Depot has the better deal I see. I'll be going there next time. My town is still dealing with tons of issues from the blizzard. Schools are still closed today in my town. So Walgreens was just to close to not take a shot at first. I have to go out of town for a Home Depot it's not to far though.

thenew3

In my own experiment, I've got my 2nd pair of keys in a safe on the opposite end of the house from the garage. where as my primary key is about 10 ft away from the car by the entrance to the garage)

After nearly 3 years, the spare key battery is still good, while I've been through over a dozen batteries in the primary key.

I've found that CR2025 lasts on average 3 months in my situation, while a CR2032 lasts 6 to 9 months. The CR2032 is just a tad thicker but fits just fine.

I've tried CR2025 from various brands bought from different places (radio shack, walgreens, cvs, home depot, amazon, ebay) and they all last only around 3 months regardless of the brand, cost or where they were purchased.

I've got a ton of CR2032's sitting around (from using them in computers and various other remotes) so I've just decided to use them in my keyfob as well.

I do have keyless go on the car.

I've had other MB's without the keyless go feature that is still on original battery after 7 years.

CR2025 has 150mah while CR2032 has 250mah so it has much more energy.

Wife's BMW with keyless go equivalent uses a CR2450 which has nearly 650mah and lasts so much longer than MB.

I don't know why MB can't design their key to take a larger battery.

jahquan3

Great info
This seems to be the consensus that a FOB staying adjacent to the car will die much quicker. I'm still trying to add some tags but can't seem to find the place to after starting the post. This will be handy for the next person who needs this info.

dariusf

This is interesting, I like to keep my car keys in the car even when on the driveway. Just no worry about looking for the key, its always there in the car

One peculiar issue I just ran in to with both of my wife's keys for the w212 was that they both ran out at the same time even as one of the keys is in the house not used. I checked the voltage and both showed 3v which should have been fine yet the car kept reporting low battery.

jahquan3

I'd be to scared someone would steal my car since I park on the street. Idk even if it was in my driveway I'd be worried lol.

That is interesting was the secondary key still fairly close to the car meaning on the 1st floor or whatever?

The G Man

A good test would be to put the keys where you normal do and go outside and try to open your car door.

pmm

If you park your car on the street, you might consider keeping your key in some kind of Faraday cage. Bad guys can buy a box that acts as a "repeater" for your key, faking your car into thinking that you are standing in close proximity with the key and allowing the bad guy to unlock your car. Completely unbeknown to you.

http://www.wired.com/2015/08/hackers...opens-garages/

KEY08

I don't see any mention of Mercedes Benz in that article.

pmm

Sigh.

http://blog.caranddriver.com/researc...nlocking-hack/

Feel better now?

pamiboy

Anyone tried keeping you keys in aluminum foil lined case while at home? If this works I'm gonna get one of those for myself. My batteries last about a year.

dariusf

Living in a suburban subdivision we really do not have any strangers walking around that might be trying if a car is open. I know there is always a chance but its very slim.

The spare key is inside the house maybe 20 feet away from the car which is in the attached garage. Two walls between. My wife keeps her key in a bag that is about 10 feet away behind a wall. If I open the car while her bag is in the house the car does not to appear to detect the key. I really did not time how long the battery lasts but it is not long at all. Will need to note the day I changed it in my car log spreadsheet. What really bothers me is that the car reported low key battery while the voltmeter showed it at 3v. The new one read as 3.25v. These are all Energizer CR2025 as I got a couple dozen on Amazon. Once these are out I will just use the CR2032 but the dozen or so I still have left even at 3 months will still last a while. Just a hassle to keep changing.

As you pointed out its a bad choice by Mercedes. They should have used CR2450 with 650mah. Using the low capacity CR2025 is just silly. Maybe they wanted to save the weight or perhaps ramp up business for the dealers. Wonder how much they would charge to change the battery )))