CO alarms - false readings?

[Ed]

Picking up my new 426 DS and getting it outfitted the last few days (will finally take her out today) But the last two nights the CO alarms have gone off in the night. The first night nothing running except the battery charger as I am on shore power and that happens automatically with the inverter charger to keep the batteries up. About 3 am two of the detectors went off - opened the boat and venteted it out and was able to get them to reset. Last night HOT, so at dinner running the A/C off of shore power and had the boat closed - again only the batteries on charge - a side note - the two 4D's needed to be topped off quite a bit when the boat was being commisioned as it had been in the water in the fall at a couple of boat shows (hull #1). The alarms started to go off first in the aft cabin, then one in the main salon and finally the one in the forward cabin - reset them and they alarmed again - then reset with the boat open and venting they reset fine. Obviously they are responding to some level of something - but I have a hard time thinking it is CO. I was a Chem. E. and then spent 20 years monitoring air in the industrial section, so I am quite familiar with detectors - but wonder if I am missing something here. Could I be getting CO? If so from where? I think it could be reacting from the off gassing of a charging battery,(SOx) but I can't smell any SOx. I have had a sinilar experience at my home where I have digital CO detectors and sometimes when charging my golf cart they will read - although only about 15 - 20ppm. I think these detectors alarm at much higher than that.Well - help me out!!!!! Can't spend the summer with no A/C, and the boat open, but don't want to wake up dead either!

 

[Robert DeJong]

False CO Alarms

The CO detectors have this wonderful quirk of letting you know whenever your batteries are low. What you're experiencing is the low voltage alarm. Its very annoying. Once the batteries are charged back up to an acceptable level, the alarm resets. The detectors are wired directly to 1 of the batteries through circuit breakers on the main panel. If that battery happens to be the low one, then "beep goes the detector". Hope this helps ~/)

 

[Frank Ladd]

Other ideas

The CO alarm on my H23.5 is run on AA batteries so you might want to buy one of those for about $20-$30. If it does not go off then you will know it is the other alarms going off on low voltage alarm. The most recent CO deaths I read about were caused by fumes coming from another boats poorly tuned generator. So if you indeed have CO gas you may need to look at your neighbors at the dock. There are others things to look for as well. Is there a pilot light on the Propane stove, propane water heater, propane refrigerator. I'm unfamilar with the big hunters so i dont know how yours is equiped but I'd definately have the dealer help you solve this problem.

 

[Scott Heller]

False Alarms

Our lead acid batteries were gassing as they died. I read (can't remember where) that gassing batteries can cause false alarms. Ensure you batteries are filled to the correct level. Ever since we replaced the house and starter on our 376 with AGM batteries there have been no false alarms. I can't claim any great scientific analysis, but am pleased with the status quo.Scott

 

[Ed]

Thanks - think it is the batteries

Not a voltage problem, this is happening at the dock while on shore power and have two 4 D's in series, so no voltage drop. I suspect it is some gasing of the batteries as they are being trickled. They were low on water when we picked up the boat and I guess that they are gasing slightly. Detectors react to types of chemicals and I suspect that they are reacting to the SOx comming off the batteries. I hope this is not a sign of a dying battery as the boat is new last fall and has only been on land over the winter months. Will give you an update. But the detectors are definetly reacting to the air in the boat as they will reset if the boat is ventilated. No pilot lights, and if the problem were from the boat next door should get worse with the boat open - but good thought, it would have never occured to me and this seems like a very likely source of a problem!!!!! Thanks for the tips.