I recently found myself troubleshooting a CO alarm on a houseboat. Inside the cabin, a Fluke CO-220 was reading 40 ppm. In the generator engine compartment, the CO level was zero (while the generator was running). We eventually found the source of the CO to be a large lead-acid "house" battery which was warm and leaking:
The OL
on the display of the CO-220 indicates a value of >1000 ppm CO. I watched it count up through 600, 800, 900 before indicating OL
.
Mechanics replaced the batteries, and ensured the battery box was properly sealed and vented. After this, the CO levels were at zero.
Can lead-acid batteries leak carbon monoxide?
This article discusses the chemical reactions of a lead-acid battery, and as far as I can tell there is no carbon involved whatsoever. So I believe the answer here to be "no".
Can a Fluke CO-220 detect gasses other than carbon monoxide?
The CO-220 manual says nothing about any gasses other than CO. In the specifications:
Sensor type | Stabilized electrochemical Gas-specific (CO)
I contacted Fluke and they responded with:
I do not know what gas batteries would put off and the CO-220 has a senor [sic] for CO only. Hope this helps.
I assume the answer here is also "no".
So then, what was going on?