The One With The Carbon Monoxide Alarm

In the early morning hours of July 5th, a carbon monoxide alarm on our boat sounded.

I wish I could follow that sentence with a story of proactive, safe actions. But unfortunately, I can’t. Before throwing a 4th of July after party for the Hilton Head Fire Department, we actually cut the wires on the alarm and tried to go back to sleep.

To preface some of the details of this story I need to say that I am probably one of the most prepare for worst-case-scenario moms out there. An example: we flew with life jackets in our carry-on bags when my kids were little. I didn’t trust that the airline ones would fit my babies in the event that we made a water landing.

Similarly, when we bought our boat the first thing we did was install 2 new smoke and Carbon Monoxide alarms. The ones that came original to our boat seemed to work, but I wasn’t going to take any chances. Over the last year, I tested the smoke feature a few times while cooking (whoops!) I can confidently say the alarms we installed worked!

Fast forward to the 4th of July. Friends came to Hilton Head and we took the boat out to anchor for the day. Fireworks over the water were the icing on the cake of a perfect day. It was just after midnight when we crawled into bed.

Which is why we were super annoyed when our 13-year old daughter woke us up at 2AM to tell us there was a beeping noise in her room.

I could faintly hear it from my bed. It sounded like a watch alarm. I’m sure I rolled my eyes a few times before dragging myself out of bed to investigate.

It didn’t take me long to decide the battery was low in our old smoke alarm. While I pride myself on being fairly competent, I couldn’t understand where to change the battery. It looked to me like the alarm was wired into the boat. Reluctantly, I woke up Brent who made the same assessment.

Here are a couple of things worth pointing out (for everyone wondering why in the world we were still on our boat):

  • The alarm was no louder than a watch beeping. It’s actually a miracle Mary Grace woke up- she typically sleeps through anything.
  • The new alarm right outside her bedroom door was not going off.
  • A quick google search of Carbon Monoxide sources produced nothing applicable. We didn’t have a gas water heater or stove. The engines and generator were not running. It didn’t even make sense for Carbon Monoxide to be an issue.

Brent and I spent at least 30 minutes debating what to do. We felt 99% confident the alarm itself was the issue. It was installed in 2003 with a 10-year lifespan. Clearly, the alarm chose that inconvenient night to die.

To be safe (remember, I’m worst-case-scenario minded) I switched almost everything off on our electrical panel and checked the engine room twice while Brent began disassembling the alarm. And by disassembling, I mean he had to cut the wires.

This detail is fuzzy (keep in mind, we were SO tired), but at some point Brent and I became aware of a slight smell. Since we couldn’t really pinpoint where the smell was coming from, and nothing on our boat appeared to be wrong, we wrote that off too. If you live on a boat, you know that this isn’t uncommon.

We got back in bed with the alarm now sitting on our counter waiting to be dealt with another day.

However, another alarm began to sound. This time we not only heard it, but realized we should get off the boat. Mary Grace was already halfway out the door and busy leashing our dog. Of course, Miller slept through everything- even the alarm going off in his room- so it was quite a surprise to him when I began dragging him out of bed.

Once off the boat, Brent called the non-emergency number to see if they could send someone over to investigate. Unfortunately, the recording on that line told him to call back during normal business hours. We both sat there for a moment. Calling 911 felt ridiculous and embarrassing. We were still 99% positive the problem was us not replacing old alarms. (The new ones NEVER went off!)

Reluctantly, Brent made the call. I’m quite certain the whole island could hear the sirens as they approached the marina.

I’m not sure who felt sorrier…us seeing 3 firefighters coming down the dock at 3AM to investigate neglected, old alarms. Or them seeing all of us sitting on the dock in our PJ’s wishing we could just be in bed.

However, they were barely on our boat when all of their handheld detectors went off. And for the first time came the realization that we actually had a problem.

I’ll spare you all the details, but it took a while to air the boat out enough for them to investigate. Around 4AM one of our boat neighbors helped determine that one of our batteries was the source. And just before 5AM the fire department cleared the boat for us to return. To say that it was a long, exhausting evening would be an understatement!

Here are a few final notes from our experience:

  • The Hilton Head Fire Department was amazing! They engaged a lot with the kids and spent quite a bit of time making sure we were okay.
  • I’m sure anyone who reads our posts regularly might assume it was one of our new lithium batteries that caused the issue. (I did!) But it wasn’t. Our boat still had a couple of lead acid batteries that are necessary for certain systems. This particular battery aided our bow thruster.
  • If you are super into chemistry, you might know that it likely wasn’t Carbon Monoxide triggering the alarm. Regardless, it was equally (if not more) dangerous and I’m so thankful we finally took it seriously enough to get help.
  • We have since tested our alarms…several times. And replaced the older ones.

We went into the next day very sleep deprived with slightly grumpy attitudes, and dark circles under our eyes…but with tremendously grateful hearts that everything turned out okay. And for all the awesome help from the Hilton Head Fire Department!

UPDATE: I’ve had several requests for more technical details about what actually happened. I hoped the takeaway from our story would be to not ignore warning signs. And to get help even if you don’t think there is a problem. I can’t even pretend to understand the science behind what happened, but I’ll repeat what I’ve been told:


One of our lead acid batteries in the engine room was overcharging due to the charger putting out too many amps (the battery was not old.) That night it began bubbling battery acid which was leaking hydrogen into our boat. Hydrogen displaces oxygen which makes it very dangerous in a small space (ie. boat.) Additionally, it’s extremely flammable.


I hope this helps clear up any confusion. If you need more technical details, I’m not your girl. But I do hope this encourages everyone to make sure the detectors on your boat, RV or home are working properly!

As always, thanks for following along on our crazy adventures! You might also enjoy reading:

The One When Everyone Said We Were Crazy

Hotel 101: How to Select The Best Place To Stay

The One Where We Went To The Emergency Room

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21 Comments

  1. Amy Deutl on July 22, 2021 at 6:45 pm

    Wow! So thankful everything turned out OK. We have also had a CO alarm go off right after changing the battery and ignored it. Would love to know what the outcome was for you. Thanks!

    • momwithamap on July 23, 2021 at 5:26 pm

      Amy, We are very thankful too. I added an update to the post because so many people were curious. It’s not my area of expertise so I tried to steer clear of technical things…I was mostly just sharing to encourage people to take warning alarms seriously. But, from what we’ve been told- for whatever reason our charger started malfunctioning and was overcharging the battery. That night it began leaking acid which was filling our boat with Hydrogen.

  2. Steve on July 22, 2021 at 8:20 pm

    Thanks for posting this! Very informative! My alarm goes off in the middle of the night too! Recently had a new Lpg gas installation done by a gas safe man, and seems to have fixed it, but with the hatches open at night due to fantastic weather (for Britain!) it’s something that I will need to keep an eye on!

    • momwithamap on July 23, 2021 at 5:24 pm

      Hummm, that’s interesting that it was fixable like that. I haven’t decided how I feel about the new vs old alarms. I’m hearing a lot of people say that the older alarms will trip for hydrogen which seems important.

  3. Ashley on July 22, 2021 at 11:41 pm

    Wow! I’m glad everyone was okay. Better to be safe and a worried momma, than not to act.

  4. Rachel on July 23, 2021 at 12:19 am

    Haha I am a “prepare for worst case scenario person” also and now I’m thinking about the life vests LOL. I’m glad you called 911. I’m sure they want everyone who isn’t 100% sure about an alarm to call!

    • momwithamap on July 23, 2021 at 5:20 pm

      Rachel, I mean I feel like the life jacket thing is somewhat legit. Right??? Haha, but in all seriousness I do hope everyone takes away from this post the importance of taking alarms seriously.

  5. Brian Burre on July 23, 2021 at 12:57 am

    Some CO Detectors, particularly the older cells, are cross sensitive to Hydrogen. It was likely why the old detectors were going off but the new were not. The new sensors were likely H2 resistant. At the ppm level H2 is not a significant issue but evacuating until the matter was resolved was still the prudent thing to do!

    • momwithamap on July 23, 2021 at 2:09 pm

      I have heard that from several people…so interesting. We’re grateful the old ones went off! Wish there was a good solution to prevent this in the future. My initial thought had been to replace all the old ones (in addition to the new ones we already have installed.) But now I’m not sure that’s the wise move. So far we’ve only replaced the one we cut off the wall that night. Appreciate your insight!

  6. Samantha Laycock on July 23, 2021 at 1:57 am

    I am glad to hear that everything worked out. I can only imagine how scary that must have been.

    • momwithamap on July 23, 2021 at 2:11 am

      Thank you! It was certainly a pretty crazy night!

  7. Capt Steve on July 23, 2021 at 11:29 am

    I’m not sure why you would spare us the details on such an important subject. This long story ended with “it was a battery issue” that is no help to anyone. If you were just looking to entertain or tell people to check their alarms, fine. But, why not help people understand so they can avoid the problem and possibly even save a life.

    • momwithamap on July 23, 2021 at 11:44 am

      Thanks so much for the feedback! I am the furthest thing from an expert on this particular subject so my point in sharing the story was to urge people not to ignore warning signs that there could be a problem. I’ve had lots of people comment on social media that they have been in our shoes and made the same assumptions (low battery, faulty alarm, etc.) What was actually causing the problem was somewhat irrelevant, but I will try to add as much accurate detail as I can (again, this is NOT a subject I know much about!) One of our lead acid batteries was overcharging. It was leaking hydrogen. Hydrogen is extremely flammable, and it displaces oxygen in a small space (boat!) Hope this helps!

      • momwithamap on July 23, 2021 at 2:07 pm

        I just added an “update” at the bottom. Again, thanks for your feedback. And I hope this helps 🙂

    • momwithamap on July 23, 2021 at 2:07 pm

      Steve, I just added an update at the bottom. I genuinely appreciate your feedback and I hope this helps 🙂

  8. Marysa on July 23, 2021 at 6:42 pm

    Wow, it is good that you were able to get this checked out and taken care of! What a scary situation, and I am glad to hear that your family is safe.

  9. Luna S on July 24, 2021 at 1:41 am

    That would be a scary situation! I am glad everything ended up turning out alright.

    • momwithamap on July 25, 2021 at 10:53 pm

      Thank you, it was pretty crazy!

  10. Danielle on July 25, 2021 at 1:50 pm

    I am so glad everything turned out okay and everyone was safe!

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