Sources of carbon monoxide - alarm going off on shore power

[marty9876]

Hi All,

Looking for thoughts/input on the process of elimination for what appears to be a carbon monoxide issue on my boat. Last 2x times I've been up to the boat the carbon monoxide alarm has been going off (detector mounted low in the aft berth). I'm assuming the source is a battery off gassing but not sure.

Changes this season - new gel starter battery (old 7+ year [from previous owner] AGM cooked itself off at the start of the season, when I got to the boat after the yard launched it the battery was hissing and carbon monoxide detector was going crazy).

Charging sources: Shore power (Promariner), solar (Morningstar) and then alternator. It appears to only happen on shore power but I always have the boat ventilated when in use so not totally eliminating other possibilities.

New batteries in the carbon monoxide detector and being it walks down the reading with ventilation and zero's out I'm assuming the detector is not faulty.

Solar charging voltage appears to be in configured voltage range, I was just on the boat off shore power for 9+ days.

Alternator charging appears to be in configured voltage range per above recent usage.

At a glance, shore power seems to be in configured voltage range also but I've not tracked it in depth. When I just left the boat I flipped on the shore charger and voltage/current coming out was in expected ranges (~ 2.5 amps, just had a long motor back to the marina)

I did a quick visual inspection of the house bank (3x gel's) and the starter battery (gel at the start of this season to match house chemistry) and nothing seems amiss.

So I'm left scratching my head. Obvious answer seems to be either the shore power charger is cooking the banks (over charging/over voltage) or the starter batter is bad (??) somehow.

Other options? There is a slight diesel smell in the aft berth (fuel tank and both battery banks all located more or less in the aft berth), not sure if that's a factor. The slight diesel smell has been there for years.

Any input appreciated.

[Cheechako]

I don't know the answer to your problem, but CO detectors are notorious for going off for no reason. To the point of being useless due to "crying wolf".

If it IS due to battery outgassing to the extent of setting off an alarm, you might consider putting in a vent hose to the battery compartment. The rise of 3 feet or so to an outlet on the coaming or aft will create enough 'chimney effect' to take it all outboard.

[Calif.Ted]

Changes this season - new gel starter battery (old 7+ year [from previous owner] AGM cooked itself off at the start of the season, when I got to the boat after the yard launched it the battery was hissing and carbon monoxide detector was going crazy).

Seems they are being fried (overcharged) when on shore power, a "hissing" gel battery sounds ominous indeed, like a bomb.

[marty9876]

Originally Posted by Calif.Ted

Seems they are being fried (overcharged) when on shore power, a "hissing" gel battery sounds ominous indeed, like a bomb.

For clarity, that was the old AGM battery than cooked itself which was replaced with a new gel battery at the start of the season. I assume some plates internally shorted out, the battery was hissing away and pretty warm. Scary as heck to be honest lifting out a hissing battery from the boat.

I leave the shore power battery charger on when not at the boat, that's for pros and cons like everything. I assumed with the failed AGM the constant charging and battery shorting out was the cause of the ongoing mess (the old AMG settled down after a few hours on the dock, resting voltage as something silly low)

I did ask the yard to turn off the battery charger until I return but if the starter battery looks fine, and has an appropriate voltage, I'm not sure how I presume it's fault (and/or the charger is faulty for that matter).

[keepondancin]

Before going too crazy, I would get a new CO detector and see if maybe there is not a problem, just that the existing one failed. I have experienced several failed detectors, the sensors apparently become contaminated by atmospheric debris and fail to sense properly, going off prematurely.

[GreenWave]

Yes try a new one. CO monitors don't last forever.

[rwidman]

In your troubleshooting, you have left out one real possibility - a defective CO detector. Replace it and see what happens.

[Sailer_Med]

Its the batteries. You can't smell rotten eggs: hydrogen sulfide?

Look this is often hard to accept, but it is the last thing you did that either is causing, triggered or is a symptom of the real problem.

So, you replaced the starting battery. I'd look that installation over very carefully; are all vents, drains etc still hooked up? What caused the starter battery to overcook? Do any of the batteries feel way too hot while charging? Why are you running a battery charger 24/7 anyway? My boat has 0 battery consumption when I'm in the slip so I normally have the shore power turned off when I'm away.

I overcooked a battery that had a bad cell or something and it took "forever" to ventilate the fumes to make my CO detector happy.

[marty9876]

New detector ordered!

No rotten egg smell (unlike then the old AGM starter battery cooked off) so that's a positive it's not something more serious. Perhaps it's like Sailer_Med and just a lot of left over fumes from before.

[Jammer]

Marty,


Good to see another Minnesotan posting.


You might consider getting a battery-powered detector that shows the ppm concentration of carbon monoxide. Then you can move it around and see if you can figure out the source.


Alcohol vapors from an alcohol stove may trip it too.

[thinwater]

The detector is likely NOT going off for no reason. They are known (in the fine print) to be sensitive to false positives from hydrogen and moisture. This is not a fault, it is an inherent part of the technology.


Google CO detector interference.

[Spot]

Originally Posted by Jammer

Marty,


Good to see another Minnesotan posting.


You might consider getting a battery-powered detector that shows the ppm concentration of carbon monoxide. Then you can move it around and see if you can figure out the source.


Alcohol vapors from an alcohol stove may trip it too.

Ditto to everything above and adding that the onboard CO detector should be an RV type not a home unit, different sensitivity levels.


I helped to kill my home CO detector after priming a large portion of the ceiling with alcohol-based primer/sealer.It started and kept going off, called the volunteer fire department, they probed a few things for CO and told me to replace the detector.

[marty9876]

Originally Posted by Jammer

Marty,


Good to see another Minnesotan posting.


You might consider getting a battery-powered detector that shows the ppm concentration of carbon monoxide. Then you can move it around and see if you can figure out the source.


Alcohol vapors from an alcohol stove may trip it too.

The old one was a typical Kiddie model with a PPM display, last I saw was 40 and then dropped to 38 before I pulled the batteries and ventilated the boat. Being the numbers moved some with initial venting made me think it might have been working

Originally Posted by thinwater

The detector is likely NOT going off for no reason. They are known (in the fine print) to be sensitive to false positives from hydrogen and moisture. This is not a fault, it is an inherent part of the technology.


Google CO detector interference.

Thanks for the Google search pointers - I think I came away with two main learnings... 1. so many more ways to blow up a boat than I originally knew (these things detect different gases) and 2. the sensors in these things wear out/can be 'over saturated' in simpleton terms from high level exposures

Originally Posted by Spot

Ditto to everything above and adding that the onboard CO detector should be an RV type not a home unit, different sensitivity levels.


I helped to kill my home CO detector after priming a large portion of the ceiling with alcohol-based primer/sealer.It started and kept going off, called the volunteer fire department, they probed a few things for CO and told me to replace the detector.

Thanks - some how I did now know there were 'marine' versions of these things. Off to Defender I go!

[Chotu]

99% likely it’s the battery. Offgassing while charging. Before buying things I might have taken the battery off the charger.