BMW 520d - key battery

[Homer]

Hi, the key fob needs the battery replaced and I went into Halfords to get it changed however when I went in the guy said "ohh you don't want to do that as if you leave the battery out for more than 15 seconds you need to have BMW reprogram it which costs megabucks". I have looked in the handbook but can't see any mention of this. Is this true? Thanks for any help.

[Kam88]

Very very very rarely would you see that happen or maybe even never make sure you check that your bmw can have battery changed. When I used to have my e46 330ci they had build in battery which you couldn't remove so had to get new key.

Also my girlfriends 1 series charges when you put the key in ignition so make sure you actually can replace the battery before you pull it apart