i have 2 keys for my car, looking at the history that came with it, one of them is about 6 months old, the other looks original due to the little Skoda logo on the back being pretty worn

the more worn looking key will lock/unlock the car from a good few metres away, with the newer looking one you have to be right next to the car for it to work, ive just fitted brand new batteries in both (Energizers with an expiry of 2016)

the only thing i did notice, is that the older key has gold contacts inside on the PCB which make contact with the negative face of the battery, on the newer key they are not gold, just grey/silver

I dont know what is it to be honest.

I can unlock/lock mine from about 100meters away.

Had to test the old hold it to your head theory, and was very surprised.

Cant help you with your question though.

Most likely cause will be the key that is only working at short range will be off frequency slightly. There is an RF carrier wave that carries the code, and if the carrier wave is slightly out of tune, the range will be poor. AFAIK this is not repairable.

Not a long term solution... but hold the key to your head when you press the buttons! Sounds odd I know.. but will almost double the distance. Wouldn't recommend frequent use though.. can't be good for ya brain

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The material of the contacts should be fine regardless, the current involved is absolutely minimal and the voltage drop difference will be insignificant.

I'd think the frequency is slightly off