CO alarm problem (?)

rgranger · May 4, 2020

Hydrogen gas is a known trigger of false alarms. Were your batteries charging?

rgranger · May 4, 2020

If it turns out to be your batteries, you may need to install a vent line in your battery compartment.

Rich Stidger · May 4, 2020

Attached is a list of known chemicals that will trigger a CO detector. Maybe one of them applies to your situation?

JK_Boston_Catalina310 · May 4, 2020

Sounds like this is a CO detector from a box store? There is a reason why something are labeled as marine grade. Humidity is a key factor in false alarms on nonmarine CO detectors.

Howard Louie · May 4, 2020

I had similar problems past two years in board- even overnight while on board the boat- in my case only forward CO monitor would go off- I changed out with new one and same thing happened. I recently upgraded all batteries to rolls AGM as my batteries were going on 10-11 years old and definitely off gassing- so far I have not had any CO alarms going off (a few weeks into it-) the off gassing from the batteries was the only explanation I could come up with and is something worth changing out to sealed or AGM regardless for health reasons - (expensive though) am on hunter 49 with six house batteries and two starter batteries (one for bow thruster and anchor and the other for starter)

Hello Below · May 4, 2020

JK_Boston_Catalina310 said:
Humidity is a key factor in false alarms on nonmarine CO detectors.

JamesG161 · May 4, 2020

Justin_NSA said:
I should get a marine grade model

Depends on your cabin humidity.
There is a link on SBO for full discussion on this.
I even called Kidde to ask about their alarm being "marine grade".
They referred me to a standard that said basically " no such grade"

My monitors went off one time and i test them 2 times a year with a cigarette/cigar smoke.

Jim...

PS: The alarm will almost "wake the dead"

JamesG161 · May 4, 2020

Justin_NSA said:
I run a dehumidifier all the time when the boat is closed up. This is the first season for this CO unit

The only thing to corrode is the battery compartment. When you change them, mark the date you changed on inside of the Kidde unit.
There is a date tag there.

IMHO ... test it, change your batteries each season, and don't worry.

Jim...

ggrizzard · May 4, 2020

Some CO units from Kidde have non-replaceable batteries.
The whole unit has an expiration date like EPIRB batteries.

Benny17441 · May 4, 2020

Your batteries may be getting older and gassing more. Remember that CO monitors have an expiration date. Their ability to work properly declines with time; check your manufacturer's recommendation. Your's is fairly new but heat and humidity can do a number specially in those designed for home use.

MikeHoncho · May 4, 2020

Hydrogen. Check your electrolyte levels, eliminate sources and if it still goes off then replace it. Residential CO detectors tend to be pretty robust and when they go bad, they go bad all the way. I learned this lesson as a young hazmat technician. Hydrogen has a cross sensitivity to most CO sensors and some are as much as 50-60 times( 1ppm do hydrogen shows 60ppm on the CO meter.) Where did I learn this? At a Excide battery manufacturing plant hazmat call. There are a bunch of cross sensitivities to them, some of the other more common are halides and florines. Humidity is a issue but usually causes a slow response when taking from one humidity level to another or low reading not a false positive but in the metering would, almost anything is possible. Hope that helps

thinwater · May 5, 2020

MikeHoncho said:
Hydrogen. Check your electrolyte levels, eliminate sources and if it still goes off then replace it. Residential CO detectors tend to be pretty robust and when they go bad, they go bad all the way. I learned this lesson as a young hazmat technician. Hydrogen has a cross sensitivity to most CO sensors and some are as much as 50-60 times( 1ppm do hydrogen shows 60ppm on the CO meter.) Where did I learn this? At a Excide battery manufacturing plant hazmat call. There are a bunch of cross sensitivities to them, some of the other more common are halides and florines. Humidity is a issue but usually causes a slow response when taking from one humidity level to another or low reading not a false positive but in the metering would, almost anything is possible. Hope that helps

Please check the numbers or provide a link. Depending on the sensor, CO sensors do detect H2, but generally are only about 20-60% as sensitive as to CO. I suspect the presenter slipped a decimal or two. The sensitivities to acetylene, Freon, and condensing water are larger, more than double.
https://www.indsci.com/blog-search/understanding-cross-sensitivities-can-help-to-keep-workers-safer/
https://www.raesystems.com/sites/de...ces/Technical-Note-114_updated_03-26-2018.pdf

JamesG161 · May 5, 2020

Justin_NSA said:
I'm thinking of adding a second CO monitor to see if both go off or just one.

My Boat has two cabins and two heads, separated by doors and even AC systems.

There is a CO monitor in each cabin area and are independent from each other. [Good safety idea]

The only CO monitor that has Alarmed is in the forward cabin, far way from any Battery.

I tested it and it worked fine and did the "reset".

Next day, I returned to find it "Chirping". Now what?
Answer: Put in new batteries.

[the old ones still tested good, but weak]

Jim...

thinwater · May 5, 2020

The trick here is that the required amount of hydrogen is less than 0.1 gram, or about 0.5-1 gram of water boiled out of the battery, depending on the monitor sensor and size of the cabin. That is 1/30th of a teaspoon. Granted H2 rises quickly, but this is very, very little. An older battery uses more water because it resists charging.

So it sounds like venting the battery box would solve it, but if the cabin is properly ventilated, it is not a problem. If the batteries are using a lot of water, that is a separate problem.

BTW, the lower explosive limit of hydrogen is 40,000 ppm.

CO alarm problem (?)

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