We have had the alarm go off when the battery died -- not sure at what level. But more importantly, if you let your battery go below 12.1 volts, you will shorten its life a lot. Don't ask me how I learned this. Keep 'em topped off as much as you can, and then charge them when they reach 50% (12.1 volts).
We just acquired our first RV-a 2017 model Fun Finder 19rb. Having fun learning about all the features. Is it normal for the co detector alarm to engage when the battery discharges to a 1/3 level?
Welcome to the forum Walkerrv-Yes as mentioned by the other members the CO detector will alarm at about 1/3 voltage. We had our new battery on our unit last year die while on Holidays in the Kootenays BC. Canada and that's what alerted us to the problem. Battery was replaced under warranty and no issues since. Silverado
2015 FunFinder 210uds, 2014 Silverado LTZ-Z71 Regular Cab Short Box, 5.3l with towing package