False CO Alarms

[STB]

I've had battery powered wireless First Alert CO+Smoke alarms in my boat for ~2 years. Never a false alarm until a few weeks ago when, within a few hours of each other, my galley and saloon each alarmed and reported relatively low levels of CO, 50-75ppm.

There was no combustion of any kind onboard or nearby, nor had there been recently. I figured my use of paints, solvents, and the occasional un- air conditioned interval on board had taken their toll and replaced the galley and saloon units.

2 weeks later. Same deal.

As before, removing the reporting galley and saloon units from service prevents the swarm from alarming.

Any thoughts?

 

[STB]

Perhaps I should add that I replaced batteries annually on schedule -- and that was just a very few months ago and that new batteries were used with the replacement detectors.

 

[Comodave]

Maybe off gassing of the house or start batteries?

 

[STB]

Maybe off gassing of the house or start batteries?

Oh. That is a /really/ good thought. Thanks!

That would be hydrogen and could do the trick. Maintenance log shows last time I checked electrolyte was 5/28/2021. And, from memory, with attendant inaccuracies, the charger was showing Absorbtion during and prior to each alarm.

Thanks!

 

[wkearney99]

That or low voltage. Most CO alarms will trip if the voltage level drops too low. The idea being they can't reliably detect CO without power so they trip the alarm.

I know this from being half-in-the-bag after MANY pitchers of frozen margaritas, on a previous boat. 2:30am trying to read the tiny lettering in the pamphlet that comes with the alarms is NOT a fun exercise. They were tied into our house battery and that ran low due to a refrigerator acting up.

 

[STB]

That or low voltage. Most CO alarms will trip if the voltage level drops too low. The idea being they can't reliably detect CO without power so they trip the alarm.

I know this from being half-in-the-bag after MANY pitchers of frozen margaritas, on a previous boat. 2:30am trying to read the tiny lettering in the pamphlet that comes with the alarms is NOT a fun exercise. They were tied into our house battery and that ran low due to a refrigerator acting up.

Thanks! Yeah, but in this case there were four occurances, on 4 different detectors (2 locations), each with new or nearly new batteries.

I'm included to bet more on ComoDave's theory of house or start batteries, as I havent checked them in 3.5 months.

 

[socalrider]

I agree with Comodave. FLA house batteries offgassing set off my CO2 alarms after I bought my boat & before I understood how jacked up the PO's charging system was.

I foolishly assumed that the CO2 alarm was faulty and continued to cook my batteries for another few weeks. If you're getting it from multiple units it's almost surely not a false alarm.

 

[Pmcsurf1]

If I don't run my bilge fan to vent the gas from my batteries I get co alarms too. First one is lowest in the boat and then it goes up. I have three co detectors. When I run bilge fan they never go off. I used to wonder why a diesel boat had a bilge blower but now I know.

 

[Pmcsurf1]

Thanks! Yeah, but in this case there were four occurances, on 4 different detectors (2 locations), each with new or nearly new batteries.

I'm included to bet more on ComoDave's theory of house or start batteries, as I havent checked them in 3.5 months.

Btw, Mine are hard wired. No batteries.