To give you some idea of how shite... ...out little ol' Rover went to the Beanz Factory at 12yrs old, sporting the original fob batteries (and the original car battery for that matter
).
My original Omega key
still works, despite having never had a battery in my ownership (13yrs), admittedly rarely used due to a split button. The other keys used to eat cheap batteries in no time, with range being so poor, always had to use the key-to-chin method. If I remember, when I'm over at big bro's, I can get him to pop new batteries in the fobs FoC, and as he used decent branded batteries from reputable sources, these last several years.
When I bought TBE of that pikey used car dealer, affectionately known on OOF as joshwyatt, I had to buy a 2nd key... ...never opened the fob up on that one, so whatever GM supply in the fobs is good for at least 6 years.
So, just beware, a pack of 50 CR2032s for 99p is rarely the bargain it looks. In fact given most OOFers seem to be so ham fisted that they break the battery holders every time they change the battery, it may well be an expensive battery
. Still, I make a tidy profit off repairing the bloody things, so I shouldn't grumble