my brother has had a C84612 running reliably for 3 years now in the central US east coast, feeding data into weewx. luc has been running a ws28xx station in suriname for about that long as well.
console batteries need to be replaced about once per year (shortest time was 9 months, typical is 11-12 months)
sensor batteries last longer.
use the battery monitor graphs in weewx and you'll get a one to two week notice before the battery voltages are too low for accurate data. or use a weewx alarm to send you an email when the batteries start to falter. if you wait too long, you'll just get wacky temperature and humidity readings.