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Discussion Starter #1
Ever since I took delivery of my Kia I have kept the smart key in a metal box (actually a Dulux 250ml paint sampler tin with lid). Today, just to check that it was secure, I held the box with the key inside near to he car and to my surprise it opened the door. I tried two other steel boxes with the same result. How is that possible?
 

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This is what I use:-

128952


John.
 
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I'm not crazy, the attack has begun.
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Ever since I took delivery of my Kia I have kept the smart key in a metal box (actually a Dulux 250ml paint sampler tin with lid). Today, just to check that it was secure, I held the box with the key inside near to he car and to my surprise it opened the door. I tried two other steel boxes with the same result. How is that possible?
Gaps (electrical discontinuities along an edge) radiate RF. You are creating a slot-antenna by merely using a metal box. There will be some attenuation, but not much. Depends on the gap of course!

Close up to the car, you may be in the inductive (magnetic component) near field. Near field is regarded as 2.pi.wavelength, and at 433MHz that's about 5 metres.
 

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Try standing so you can just reach to open the car door with your left hand and holding the box in your right hand stretched away as far as you can from the car. I’ve made a faraday cage by lining a box with tin foil, and although if I hold it near the car door it unlocks, it doesn’t at full “wingspan”. So I keep it more than that distance away from my front door.
 

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I used an eBay Faraday pouch for about 2 years; checked it at purchase-time & was fine. Demoed it about 6 months ago, only for it to fail! I suspect the mesh may have fatigued at the fold, so that got binned & replaced. The moral seems to be that the radio signal will escape through the smallest gap. Does your tin have any anti-rust varnish coating round the lid-to-case lip? I suggest sanding lid & tin with emery & get it shiny, & try again. You need good electrical contact all the way round.
 

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Originally bought "defender" pouches off ebay, just after buying the car, but after a few months found they were not secure and let the signal out.

Bought a cheaper replacement from Aldi last year and have found they work fine. Key can be in the secure side of the pouch next to the car and the door won't open and even if inside the car, it won't start with the key in the secure side.
 

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Ever since I took delivery of my Kia I have kept the smart key in a metal box (actually a Dulux 250ml paint sampler tin with lid). Today, just to check that it was secure, I held the box with the key inside near to he car and to my surprise it opened the door. I tried two other steel boxes with the same result. How is that possible?
The lids typically don't make contact with the tin, because of plating or paint. If you get a dot punch (or nail, if you don't have one) and gently tap small dimples around the top edge of the tin every couple of inches then the tops of the dimples wear though the paint and make contact. Works fine.
 

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Discussion Starter #10
Thanks everyone for all the advice. I did a little experiment. The Kia e-niro key worked at 1.2m outside the tin. Inside the tin 0.8m. After I sanded off the coating on the edges it totally shielded the key.

BTW I asked the dealer about the risk of theft when I ordered the car. He told me not to worry because they don't steal Kias, only cars like BMWs and Mercs.
 

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Just take the battery out and use the key! ;)

It might even make sense to put an "on/off" switch on 'keyless' fobs, perhaps?
Or a movement sensor, which switches the key off after say one minute of being stationary and is reactivated by movement.

I had two solutions for the Kia Soul keys.
Main key, i kept in a faraday pouch when not in use.
Spare key, wrapped in aluminium foil inside a small oxo tin (other brands of gravy are available though not necessarily in tins). That was impervious even when held next to car.
And picking up from Fred above, The car was a Kia Soul.
 

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I am not worried about this issue... certainly not worried enough to do these kinds of things. The way I see it is that there are loads of cars to choose from and if they choose mine... well, it is insured.

I have spent a lot of money to get a car with hi-tech... I intend to use it with the minimum of inconvenience.
 
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