Where is the CO coming from?

[BayMan]

1987 Hunter 450.

I put a house CO detector in the aft stateroom. I equalized my batteries and it went nuts. I ran my AC and the reading went up to 40 ppm. This has happened when running heat also. Neither time was there any combustion on board or anywhere around me. During the equalization there was nothing else powered up. The reading was 0ppm the last several nights were we didn't run AC or heat.
What is making the detector react like this. I first thought that the culprit may be battery fumes from the equalization but that doesn't explain the AC.

 

[LeoLambert310]

Do you have solar panels if you do are they in the charging mode when the CO alarms?

 

[Davidasailor26]

Where is your AC condenser located? Is it in the cabin, or is it in a lazarette or someplace where it could be pulling air in from the engine compartment (even if the engine hadn't run in a few hours)?

 

[Ken Cross]

Try swapping CO detectors with your house. Without combustion it certainly sounds like a false positive.
Years ago an Air France 777 turned back for a cargo fire indication. It turns out the live frogs they were carrying (not a joke) produced enough gas to fool the smoke detectors.
It's hard to make anything fool proof.
Ken

 

[Ron20324]

Might the equalization voltage been too much for the detectors?

 

[Ron20324]

Might the equalization voltage been too much for the detectors?

 

[Rich Stidger]

Battery charging and gassing will definitely set off the CO detectors. Freon from an AC will also set it off. See the attached list below that was sent to me by Nighthawk regarding their CO detectors. This list does not seem to be widely known.

Also, when I run my generator with a heavy load, the output voltage increases from a no-load condition. This higher voltage will cause my charger to increase its output voltage and the charging current. If your batteries are already fully charged then maybe excessive gassing is occurring.

 

[Dennis Kitchen]

Ditto to what Rich said,
My CO detector in my RV kept going off occasionally and then almost constantly. Knowing there was no CO I finally un-hooked it from power. Then I woke up in the night with burning eyes and a caustic smell. I checked the battery charger and found it going full charge. I removed the battery and checked the fluid; nearly empty. How I kept from having an explosion and/or fire I'll never know.

 

[BayMan]

No solar. The AC condenser is in cabin. This first happened with a new detector so I brought in my home detector that doesn't just alarm but shows a ppm reading. I guess the one thing we all agree on is that there is very likely no CO despite the alarm. I looked (quickly) for a marine CO detector but didn't see one- that's a pretty good tip that the marine environment produces too many false alarms.

 

[smokey73]

No solar. The AC condenser is in cabin. This first happened with a new detector so I brought in my home detector that doesn't just alarm but shows a ppm reading. I guess the one thing we all agree on is that there is very likely no CO despite the alarm. I looked (quickly) for a marine CO detector but didn't see one- that's a pretty good tip that the marine environment produces too many false alarms.

I'm not so sure about the conclusion that the marine environment produces too many false alarms. It may just mean that there is nothing unique about the marine environment that justifies a "marine specific" unit. Until you are absolutely sure of the cause, assume its reading something "bad" even if its not CO. If its showing a ppm reading, its detecting something. Based on Rich's list is it possible you have a tube of sealant with the cap off or a can of toulane, acetone or something stored in a hidden locker that may be leaking? The alternative is not waking up some morning or waking up, if you're lucky, choking on some nasty gas. Ignoring a gas detector is a sure fire way to end up sick or dead. Do you really want to take that chance? By the way, I have a functioning dual sensor CO/smoke detector in my main cabin and have never had a false alarm in 3 years. I also have an AC unit and my start battery is under the sole in the main cabin. (House batteries are in the port lazarette). BELIEVE YOUR INDICATIONS!!!!! (An Admiral Rickover axiom that has always served me well).

 

[Rich Stidger]

There are lots of common cleaners that we use that will set off the alarm. Perhaps the AC is circulating vapors from one of those cleaners? The only non-CO vapor that has set off our alarm is from battery charging. At 2am. A very bad night's sleep, and that was before I got the list from Nighthawk. As for home vs marine CO detectors, my opinion is that the only possible difference is that the marine units may use coated circuit boards to prolong the life of the detector.

 

[JamesG161]

I put a house CO detector in the aft stateroom

What is the Brand and Model? There are several CO monitoring methods and devices.

My Kidde CO uses a micro radioactive particle which "ionizes" carbon containing air. Hydrogen may trigger an alarm. How many feet from your batteries is the detector? It would take a charger "run amuck" to make enough hydrogen even cause an explosion from my Hunter ventilated house battery compartment.

I equalized my batteries and it went nuts. I ran my AC and the reading went up to 40 ppm. This has happened when running heat also. Neither time was there any combustion on board or anywhere around me.

If your AC had an electrical heat assist, dust on that element may "burn off" and trigger it, but that would "burn" off and stop.

Wild azz guess...

You have an electrical wiring problem on the 120VAC side. Put the detector near your switch panel and repeat the current draw. Look for a loose or corroded 120VAC wire connection.

Tip: Use the detector like a metal detector, sweep and find. The closer you are to the source, the more rapid the response and of course concentration shown.
Jim...

PS: It takes ≥ 4% hydrogen, oxygen and an ignition source to get combustion. Rare on a ventilated battery compartment.

 

[JamesG161]

This is a good discussion on CO detectors in a marine environment.
http://forums.sailboatowners.com/index.php?threads/carbon-monoxide-detector.177533/
Jim...

 

[BayMan]

I left the boat shut up tight for 3 days on shore power. The only things left on were the charger, the frig and freezer and the AC outlets. The CO meter read 15 when i arrived and went down to 0 when I opened up some hatches. Has to be the battery charger?

 

[Maine Sail]

Guys,

There are only two marine CO manufacturers left in production, Xintex and Safe-T-Alert. I tend to prefer the Safe-T Alert. Not many companies are willing to pony up for the Marine UL portion of UL testing..

 

[Charles Erwin]

Highly interested in this matter. What does the UL marine testing regime do that is lacking from the normal UL testing? Is there anything in the Marine testing protocol that would explain the unexpected results in this case or would those things happen no matter marine UL compliance?

Charles

 

[All U Get]

I left the boat shut up tight for 3 days on shore power. The only things left on were the charger, the frig and freezer and the AC outlets. The CO meter read 15 when i arrived and went down to 0 when I opened up some hatches. Has to be the battery charger?

You know what you do have, but you don't know what you don't have. You might have to give up the charging, frig, and AC to see if that's producing a cross contamination. If the reading is then zero, you have narrowed it down to the mentioned four circuits. Try not to clean anything in the meantime.

All U Get