Joined: Aug 2010
Posts: 12,727
Likes: 2,105
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
Varies by model. My VDO bike computer, the computer only lasts half as long as my speed and cadance sensors. My heart rate chest band batteries usually last for years.
I replace the batteries when they go out. Exception, on the one bike where I have a cadence sensor, I assume that sensor will use power as fast as the speed sensor so when one of those two go, I replace them both.
I usually buy CR2032 batteries in batches, store the extras in the fridge. So, when one goes, I already have the replacement for it.