Even the Silver Oxide batteries drop of quick at the end of there life but they last for ages, I usually test mine to see if there still near 1.5v.
The only trouble I have had is from the cheap cards of batteries off eBay to be honest I've had them fail on the day I put them in. They also leak a little and corrode the copper pin in the centre of the collar which goes black, doesn't seen to happen with the better batteries.
Cheers Arry