CO detector saved me -- with no CO present

[LeighWebber]

A couple of years ago I installed a Webasto diesel forced air heater. Wonderful unit -- works flawlessly. Last month, I replaced my ancient and failed Xantrex battery charger with a the Abso AC1260. I chose that unit because it supports three battery banks. I have a brand new house bank with 510 AH deep cycle AGM batteries, and an aging starter battery (flooded, maintenance free). At first, I didn't have a cable to connect the starter battery to the Abso, so I ordered one.

The outside temp last evening was about 55, headed down to about 45 overnight. I came onboard and flashed up the Webasto. Nice. Later in the evening I finished my charger installation by connecting up the starter battery on the charger's Channel 2. The starter battery was really run down (separate long story) -- only had about 8 volts in it. But I hoped the ABSO would bring it back to life. I could see the charger cycling on and off to coax the starter battery up to a reasonable voltage, then after an hour or so it kicked in and began pumping 25 amps or so to it.

I went to bed at about 10 pm. At around 1 am I was awoken by my CO detector. I have two of them -- one up by the V berth, and one in the main saloon. The former triggered first, followed shortly by the latter. I suspected a wind from astern was blowing exhaust fumes into the boat, so I shut off the Webasto, opened all the hatches, and turned on the three fans in my boat (my cheap air conditioning system). I watched the CO levels start to go down, and when the detectors stopped chirping, I hauled out my cold weather sleeping bag and crawled in. I would check for the source of CO in the morning. To be safe, I left all the hatches open.

In the morning, CO levels were zero. I closed the hatches, and made breakfast. About a half hour later, the CO detectors went off again. WTF! The Webasto had remained shut off, so it couldn't be the source. I checked up top to see if some huge motorboat had parked with its exhaust pointing at me, but nothing. Beautiful, fresh air morning. In the boat, however, I smelled something -- couldn't put my finger on it. I opened all the hatches again, turned on the fans, and cleared the CO levels down to near zero again.

Then my brain kicked in. The charger. I opened my engine compartment hatch and looked at the starter battery. Copious volumes of white smoke were pouring out of the thing! I opened every hatch, unplugged shore power, and got off the boat. An hour later I returned. The smoking had stopped, the funny smell was gone, and the CO detectors were quiet.

I don't deserve to be alive. I failed to check that starter battery as the ABSO began pouring on the amps. I think it was so badly sulfated that the heavy current and charging voltages caused it to emit hydrogen gas PLUS hydrogen sulfide gas. What saved me was my pair of inexpensive CO detectors. They triggered on the hydrogen sulfide, I think. Even though I failed to shut off the charger at 1 am, with all the hatches open and the fans running, the bad gas was cleared. When I closed the hatches in the morning, the gas built up again, and the CO detectors went off.

I had no idea that a CO detector could do this. These were NOT the "dual gas" models (propane + CO). I have separate propane detectors, and they were silent.

Lessons. First, make sure you have a couple of CO detectors even if your boat has no heating system of any kind. Second, don't connect a powerful charger to a failed battery. Third, when you reconfigure your charging setup, monitor the charging voltage and current for the first several hours to make sure everything is operating as it should. Fourth, when your batteries have been deeply discharged, watch them as they charge and stop everything if you see any gassing, bubbling, overheating, etc.

[Steadman Uhlich]

Howdy Leigh.

Thank you for writing such a good, detailed post.

I recently recommended a CO alarm, and your post confirms my belief that they are good to have aboard a boat, and not just for the usual reasons or sources of CO.

I am glad you woke up, and are still with us.

[Nicholson58]

We are handed many lessons through life. We survive most of them.

Thanks for the post. Great information.

[CaptTom]

I've seen CO alarms go off from regular battery charging. Apparently the gasses from batteries are detected as if they were CO. You usually get the "rotten egg" or "holding tank" smell from overcharging batteries, too. Not sure if this applies to AGM's, my experience is with FLA's.

In this case, I don't think the fumes would have killed you, but the fire might have. I'd have stayed aboard, but NOT within range of the battery, in case it caught fire or exploded.

Anyway, good reminder for everyone; if the CO alarm goes off, check the batteries second, after engine CO sources are eliminated. The Webasto would be in third or fourth place, after cooking appliances and anything else with a flame.

[a64pilot]

CO detectors and most gas detectors will detect gases other than what they were made for.
CO detectors are also sensitive to Hydrogen, your battery does not give off CO and while it may have caught fire or something it wasn’t going to asphyxiate you.

Biggest lesson is that a dead battery, is often dead, and if your going to try to recover it anyway, don’t do so with it mounted, removed it and put it somewhere safe.

[S/V Alchemy]

Very interesting. I have a CO detector aboard, maybe I'll have two!

[tiopirata]

Originally Posted by Nicholson58

We are handed many lessons through life. We survive most of them.

Thanks for the post. Great information.

So very true

[AndyEss]

Hydrogen sulphide (H2S) is a deadly gas. Further, while human olfactory senses are exquisitely sensitive to H2S (we can smell H2S in the parts per billion range, women are usually more sensitive to H2S than men), our sense of smell rapidly becomes desensitized to H2S when it is present. That's why respirator filters aren't used with H2S in industrial settings as the user can't tell when his respirator filter has become saturated with H2S and excess gas starts flowing through the filter to be inhaled.
I'm not sure how much H2S is produced during LA recharging, but H2S is deadly.
Glad the op is still here to give us such a good summary for our edification.

[Parrothedd]

You are a very lucky sailor. If you were Felix The Cat, you would have used up one of your 9 lives. Smoke and Carbon Monoxide detectors save lives!

[Sojurnr]

Originally Posted by Nicholson58

We are handed many lessons through life. We survive most of them.

Thanks for the post. Great information.

Point of order: We survive ALL but the LAST lesson.

I agree, a very meaty post, written with humility.

Thanks!

[Squanderbucks]

If u have not already those batteries in question should be gotten off the boat ASAP. Sulfating batteries can not only kill you from the gas (think WWI trenches) but the can explode or catch fire.

[rthompsona]

Our CO detector has gone off twice. Both times it was battery related.

The first time it turned out that our old promariner charger was overcharging one of our banks. The spare cabin on our catamaran has an access panel for the battery compartment which let the gas in. It was fortunate that we had a detector in both cabins, because we might not have realized the problem until it was too late

We wound up replacing the the batteries because we were getting solar. We replaced the charger as well

The second time it tuned out that the fill cover on one battery got knocked off.

That allowed enough gas to vent to set off the detector.

I would never go back to a straight smoke detector.

[a64pilot]

Find an instance where someone has been harmed by an off gassing lead acid battery.
I have looked, and can’t. I just don’t think it happens, ever.
Weight is how they harm mostly, followed by electrical shorts outside of the battery and fires, spill acid on you etc. but nothing about inhalation of gasses.
Best study I could find was in mines, apparently they have huge lead acid batteries that power some mining vehicles, and of course mines are an enclosed space.

[Dooglas]

An excellent post with several good take home lessons. Yes, every boat should have CO detectors. And yes, when the CO detector alarms; check engines, heaters, AND batteries. And finally, you really can't bring a truly "dead" battery back to life so nothing but trouble comes from trying.

[rthompsona]

In our case, we had two guests sleeping.
They complained of sore throats when the detector woke them , and both had severe headaches which lasted most of the next day.