Do Keys Fail if Not Used

[mbenz76]

I only ever use one car kay. The other (my spare) is tucked up safely in my safe.

However, I have read that MB keys can stopp working if not used for a while.

Is this true? And if so after how long roughly? Because if it is then I will rotate the key that I use.

 

[st13phil]

It's an urban myth that they fail if not used. However, I personally rotate my keys between the one in use and the spare one every six months or so so that I get the most use out of all the batteries I paid for...

 

[m7m]

As with any battery, the charge will reduce with time. It is therefore best to rotate the keys in case you need to use the second key one day and find that the battery is flat.

 

[Bobby Dazzler]

The battery could go flat, and potentially need to be re-synched to the car, but not sure it would stop working for any other reason.

Only last night I fitted new batteries to our keys for both our C and ML. The spare keys have never really been used - kept for spare only.

The fob battery in the spare ML key is the original and un-changed in close to 6.5 years. Superb range and worked straight away, so I only replaced the batteries in the in-use key and left the spare key with the original batteries fitted.

Again the fob battery in the spare C key is the original and unchanged in just under 6 years. The key didn't work but the LED in the key illuminated very faintly. I assumed it would now be out of synch with the car, but changed the batteries anyway.

First few attempts to use the spare C key with new batteries reconfirmed my thinking that the key was out of synch. I pressed it once more for luck, and the car locked/unlocked and was fine thereafter.

So if you've not used the key - the batter could last 6 years plus, but it's no guarantee. I would suggest changing the batteries in your spare for good measure every other time you have the car serviced.

 

[Dec]

(my spare) is tucked up safely in my safe.

That’s not a good strategy to employ, if your regular key ever fails, for whatever reason, or it is lost, you will have to return to your safe to get the spare key, which is ok if you are not too far from home.

I keep my spare key hidden inside the car and a spare flat key hidden on the outside body of the car, this allows immediate re- entry to the car, both keys are fully protected from damp etc.

I cant remember how I did it but I managed to locked my key in the boot, however because of this strategy I was able to get back inside the car within seconds despite alarm going off for a short while.
The moral of the story is to keep your spare with the car and not at home.


Dec

 

[Baron_Samedi]

Probably tempting fate here but I have only needed a spare key while out and about on one occasion in thirty years of driving.

If this unfortunate event occurred I feel that the AA are better placed to deal with the issue than me leaving a key in the car.....

 

[Alps]

i wouldnt condone the "leaving the spare in the car " idea, nor would your insurance company if your car got stolen (with or without) the key.

it`d only take a good friend and a phone call to have a spare collected from home and brought to you.

back on subject, i would just use the spare once in a while to make sure it worked

 

[Dec]

There is a big difference between "leaving the spare in the car " and a hidden key inside the car but I take your point about insurance.

Dec

 

[rees_A]

If you leave your spare in the car and your primary fails, how are you going to unlock your car to get to the spare?????

 

[Baron_Samedi]

I think Dec secrets a blade somewhere on the vehicles bodywork.

 

[renault12ts]

Remember the batteries in Mercedes keys are for opening the doors etc. The key will still start the car with no batteries in. So, back to the OP...is the question about batteries or about the key's ability to start the car?

 

[mbenz76]

Thanks for the replies. I was refering to the key not working at all. I have read a few things but now people mention it I think it is the key losing synch that I am thinking of.

I will rotate my keys every couple of months just to make all is well.

 

[renault12ts]

Can't think why it would lose sync.

 

[stevesey]

If you leave your spare in the car and your primary fails, how are you going to unlock your car to get to the spare?????

I think Dec secrets a blade somewhere on the vehicles bodywork.

Hm - whilst I don't think I'd go as far as leaving the spare in the car, the idea of hiding a blade does have an attraction - there are plenty of places one could hide one.

We always take the spare with us when away from home for more than a day trip (too avoid the potential 100s of miles away from the spare key when you need it problem).

 

[Dec]

a spare flat key hidden on the outside body of the car, this allows immediate re- entry to the car

Dec

rees A
There is a flat key hidden on the exterior of the car, this opens passenger door, alarm is triggered, the hidden spare key fob is retrieved, alarm disarmed and off you go, this all takes about 30 seconds, much faster than the AA.

Dec

 

[Dec]

Remember the batteries in Mercedes keys are for opening the doors etc. The key will still start the car with no batteries in.

In my case the one button flip out key fob is necessary in order to disable the immobiliser.

Dec

 

[renault12ts]

^ Yes but the OP has a nice brand new 212.

 

[mbenz76]

I don't think I'll be leaving a key hidden around the car

Although I do often take a spare key with me if going away for a day or more. My key in my pocket and the spare either left at the hotel or in the wife's handbag.