CO2 detectors

[Akapeterc]

Anyone have any idea why my CO2 detectors would keep going off when the boat is locked up tight at the marina on hot days. They are less than 12 months old as I replaced them all because they were going off. When I get a board and open up the windows they go green straight away but for some reason when the boat is locked up tight on hot day they go off. Only thing running on the boat besides refrigeration is the battery charger. Any ideas?


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[FamilyVan]

Aka, I think that's a CO detector. But no, I don't know why, mine has never gone off and I have alcohol heat and kero lighting.

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[Scott Berg]

outgassing FLA Batteries?

[Sailmonkey]

Originally Posted by Scott Berg

outgassing FLA Batteries?

That's hydrogen....... But I don't have any idea either.


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[Garrettw]

The standard CO detector element used in most residential detectors also cross hits on hydrogen at a 1:10 ratio (ppm). This means that if your flooded batteries are outgassing then it will make your detector false alarm on CO. I had the same problem and went through a variety of detectors until I figured out the issue. It actually took me borrowing a pro detector and also reading the spec sheets on the detector elements to realize what was really going on.

[Jim Cate]

So, if the alarms are, er, alarming to you, perhaps venting your battery area to the outside would be a good idea. It is, I believe, required under many classification rules, but in many production boats, not directly accomplished.

Jim

[SteveInMD]

I had the same problem with a household type CO detector when it got very humid. I switched to Xintex CMD-4MR CO Sentinel Carbon Monoxide Detectors. Problem solved.

[dannc]

Originally Posted by SteveInMD

I had the same problem with a household type CO detector when it got very humid. I switched to Xintex CMD-4MR CO Sentinel Carbon Monoxide Detectors. Problem solved.

Yep, the OP needs to read the specs on is detectors. When we moved into our new house which required FIVE smoke detectors, they would go off at around midnight. Great fun to be waken from a deep sleep by FIVE alarms SCREAMING. The alarms are lined so if one goes off, they all go off. After reading the small print, it seems these detectors will go off because of humidity and dust particles.

My best guess was that the alarm was alarming because of humidity building up at night after people had taken showers. The natural airflow in the house would move the humidity to one end of the house where there was a smoke, errr, humidity detector.

Humidity is just a pain, but if the alarms are going of because H, that is a bigger concern.

Later,
Dan

[Dockhead]

Originally Posted by Jim Cate

So, if the alarms are, er, alarming to you, perhaps venting your battery area to the outside would be a good idea. It is, I believe, required under many classification rules, but in many production boats, not directly accomplished.

Jim

This sounds good in principle, but in practice -- how do you do it?

My boat has fan-forced ventilation in both battery boxes, which must have been expensive to build with all of the ducting required. This is nice because it eliminates smells. But does it keep hydrogen out of the interior space? I really doubt it. First of all, it only works when either the main engine or genset is working. So if you are charging from shore power -- no joy. Second, I really doubt that the tops of the battery boxes are gas tight to the extent that hydrogen -- the lightest element by far -- can't escape. I have never heard of a hydrogen explosion on a boat, and hydrogen is not toxic, so why worry about it?

[hellosailor]

"Only thing running on the boat besides refrigeration "
I wonder if they can also detect a refrigerant gas leak. Devices sold to do that, using a diode sensor, will show a leak of as little as 1/4 oz. per year in still air.

Divide and conquer: Air out the boat, stick some ice in the fridge, shut the refrigeration AND charger and go to lunch. Some back and see if the detectors are upset. If they are...odds are it is something else. Now go out for tea, with just the battery charger running. Does that upset the detectors?

You should be able to pin down the fridge or charging as being a problem, or not, just by some simple "process of elimination".

No stored gasses, propellants, aerosol cans or camping gas cylinders onboard?

[Akapeterc]

Thanks for all that info, I had thought that it may be the hydrogen from the batteries but thought that wouldn't be detected by the CO detectors. They read out when you push the button that they are picking up only 100ppm. When we are aboard with a few windows cracked open, no problems, it only occurs when the boat is locked up at the marina. I don't know how I could vent the battery banks they are in the middle of the boat. Really need to put the covers up over the boat so I can open some windows, but they are a real pain to put up and take down. Cheers

[Garrettw]

Originally Posted by Akapeterc

Thanks for all that info, I had thought that it may be the hydrogen from the batteries but thought that wouldn't be detected by the CO detectors. They read out when you push the button that they are picking up only 100ppm. When we are aboard with a few windows cracked open, no problems, it only occurs when the boat is locked up at the marina. I don't know how I could vent the battery banks they are in the middle of the boat. Really need to put the covers up over the boat so I can open some windows, but they are a real pain to put up and take down. Cheers

This likely means you are seeing 1000ppm of Hydrogen (H2). The lower explosive limit of H2 is 40,000 ppm so you're ok from that standpoint. Someone else in the thread asked what's the big deal, so what if you are detecting hydrogen too. The problem is that you never know if you really have a CO problem. Since someone using their boat is likely using to be charging batteries often this ends up being a continual problem.


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[ranger58sb]

Originally Posted by Akapeterc

Anyone have any idea why my CO2 detectors would keep going off when the boat is locked up tight at the marina on hot days. They are less than 12 months old as I replaced them all because they were going off.

Call MTI's service tech and ask.

Originally Posted by Garrettw

The standard CO detector element used in most residential detectors also cross hits on hydrogen at a 1:10 ratio (ppm).

Originally Posted by SteveInMD

I had the same problem with a household type CO detector when it got very humid.

The CO detector pictured is not a residential unit.

Also, MTI told me recently there is no difference between their "marine" and "RV" units other than the labeling.

-Chris

[a64pilot]

I have doubts that hydrogen could accumulate in a boat, mine at least is not air tight, the companionway boards have a gap at the top and a lot of people have vents, I think hydrogen would escape as quickly as it was produced.

But batteries sometimes have a rotten egg smell especially if over charged, that's Hydrogen sulfide?, which I think isn't harmless?

[a64pilot]

CO detector in my RV would go off if the voltage was low. I just turned it off unless we were using the heater