[Leesparky]

So, I have GLA 45 AMG 2017 (UK) - I love it!

i’m having to replace the key battery every couple of weeks and it’s driving me nuts trying to figure out why!

It’s the keyless go one. All works fine and then it doesn’t every couple of weeks, showing the ‘key not connected’ fault. Replace the battery and then all good - for a couple of weeks!
Today I disconnected the + battery connection (waited 5 mins) and connected all back up again (saw this as a fix somewhere). Didn’t work, so replaced the battery again.

Any ideas (apart from ‘take it to Mercedes!)?

 

[Huey52]

If the key fob is RF near the vehicle it will deplete more readily given frequent communication. Try moving the fob further away from the vehicle or store in a "Faraday Cage" type box.

Our master bedroom is over our garage and as my wife brings her pocketbook to same in the evening that fob battery depletes far more readily than the more distant backup.

 

[Leesparky]

Ah, know what? That could be it. My car keys are near the car (obviously there’s a wall in the way), but in the downstairs loo.
Any recommendations on a cheap ish Faraday cage?

 

[Huey52]

Ah, know what? That could be it. My car keys are near the car (obviously there’s a wall in the way), but in the downstairs loo.
Any recommendations on a cheap ish Faraday cage?

A quick Amazon search renders: https://www.amazon.com/Upgraded-Faraday-TICONN-Premium-Protector/dp/B07MDF5TX9?th=1

But I have no experience with same.

 

[Leesparky]

Yep, did the Amazon search myself. No worries

 

[RamaGLA]

It will say in the gauge cluster when the key battery is low. Test the old ones with a multimeter to see if they’ve actually gone bad or if there’s another issue

 

[RamaGLA]

Also, never disconnect battery + first. Always - first. If the + touches another metal component it will short and potentially cause expensive damage.

It always goes - off first, then +, but + goes on first and - last. So reverse order

 

[Huey52]

Also, never disconnect battery + first. Always - first. If the + touches another metal component it will short and potentially cause expensive damage.

It always goes - off first, then +, but + goes on first and - last. So reverse order

Exactly. With the proper disconnect/connect process you're basically denying the DC circuit a source of electrons and thereby possible shorting (DC electron flow from low potential ground negative to high potential positive). My professors wouldn't like this analogy but you can think of the positive terminal as a vacuum cleaner and you're denying a source of dust (they didn't like water pressure/volume/restriction analogies either).

 

[Huey52]

It will say in the gauge cluster when the key battery is low. Test the old ones with a multimeter to see if they’ve actually gone bad or if there’s another issue

One never knows how long a CR2025 camera/wafer battery has sat on a hardware store or pharmacy shelf. Also the new childproof "bad taste" coatings on some brands can be problematic. I therefore clean off same with isopropyl alcohol prior to multimeter testing and installation.

 

[RamaGLA]

One never knows how long a CR2025 camera/wafer battery has sat on a hardware store or pharmacy shelf. Also the new childproof "bad taste" coatings on some brands can be problematic. I therefore clean off same with isopropyl alcohol prior to multimeter testing and installation.

The battery flavour comes off with isopropyl alcohol? My dad had issues getting a Duracel CR2025 to work properly with his AirTag since it had the flavouring. we got some different batteries for the AirTags, but if this is a solution then you've saved me a lot of time searching for unflavoured ones!

 

[Huey52]

The battery flavour comes off with isopropyl alcohol? My dad had issues getting a Duracel CR2025 to work properly with his AirTag since it had the flavouring. we got some different batteries for the AirTags, but if this is a solution then you've saved me a lot of time searching for unflavoured ones!

Well, I've not post-cleaning tasted them, but it does seem to better their performance.

 

[Whiterabbitt]

well, I'm a day late and a dollar short, but for testing purposes, the cheapest faraday cage you can get is some tin foil. Works like a CHAMP.

Might get you an answer quicker than buying something. Then if it works, you can buy something nice directly.