CO alarm activation

[Phil.]

I thought I would post this just for the interest factor however if anyone thinks I have either a CO alarm or battery charging problem please feel free to educate me.

Yesterday on returning to the boat after an hour away one of our CO alarms was chirping away. We have three such alarms the one that was activated is in the rear cabin next to the engine room. We also have one in the bedroom in the centre of the boat which did not activate and a further one in the saloon at the front. This one did not activate but it was showing a peak reading of 18ppm, I think it needs to get to 50ppm to set it off.

No solid fuel stove, gas or diesel was being used at this time or had been. So on this basis I assumed it was not CO unless it entered the boat from outside which I thought unlikely.

The only thing remaining was I had read that batteries gassing during charging may affect CO alarms. The weather was bright sunshine so the solar had the batteries in the absorption phase which temperature compensated was charging batteries at 15.05 volts. It was also very windy outside and the wind was blowing directly onto the stern of the boat. I therefore assumed that any gas being created by the batteries in the engine room was then being blown into the rear cabin and activating the nearest CO alarm. It continued along the boat but by the time it reached the centre alarm the concentration was below the activation level. Travelling still further along the boat it reached the front and registered a reading. After ventilating the boat and the alarms there were no further readings which now showed 0 ppm.

Well that's the story so is my assumption correct or am I barking up the wrong tree.

I would be interested to know if this is a common issue with CO alarms and also at what concentration the gas from the batteries would be explosive. Just to add there were no bad egg smells and the batteries were not hot.

Thanks

Edited May 14, 2015 by Phil.

[ditchcrawler]

I have heard of gassing batteries causing CO alarms to trigger

[churchward]

Was a boat more close with a running engine?

 

We has a raised ready on a CO detector once when a boat moored alongside with a roof exiting exhaust stack. Some of the exhaust entered through an open window and although the CO detector did not go off it showed a non-zero reading.

[GoodGurl]

check the batteries in the alarm, mine goes off if batts are low

[Phil.]

Was a boat more close with a running engine?

 

We has a raised ready on a CO detector once when a boat moored alongside with a roof exiting exhaust stack. Some of the exhaust entered through an open window and although the CO detector did not go off it showed a non-zero reading.

 

No it could only have been a passing boat which is why I think it unlikely that the cause was from outside the boat.

 

 

check the batteries in the alarm, mine goes off if batts are low

Internal batts ok and alarm is functioning as it should.

[Bobbybass]

We had a fixed alarm on the boat...and it often went off from the batteries charging.

 

I shut the gas off.....for several days...but let the sun come out and the solar start charging and it would go off especially if we left the boat and the doors were shut.

 

Don't get me wrong...these things need investigating..that's what alarms are for...

[mark99]

Our CO alarm went off the first time we plugged into shoreline. Gassing of batteries.

[Phil Ambrose]

Regarding the threshold for alarms to go off it is worth noting that as Phil so rightly says 50ppm is the trigger point but the level must have been holding for at least 1 hour I believe, for higher ppm readings the time factor is reduced pro rata until a point is reached where a very high ppm level will cause an immediate response from the alarm

Any reading below 50ppm for a short while is considered to be acceptable and can be caused by things such as a bit of blowback when stoking the fire or having a lot going on galleywise.

It's difficult in a NB to fulfil all the correct fitting criteria so we should expect on occasions to see readings above zero from time to time.

Phil

[DaveR]

How old is the detector? I have just had to change one of mine as it was 5 years since activation. Check the back of the unit.

 

Dave

[pearley]

I've been woken in the night twice by the CO detector picking up a gassing battery. I know it was the battery as I could smell it as soon as I went into the engine room.

[mango]

If batteries have vent holes at either end then just vent them overboard, so that you don't have to breathe noxious fumes. Obviously the hole at the other end of the battery needs to be plugged. Getting rid of a mixture of hydrogen and oxygen produced by charging batteries could also avoid an explosion.

[andyb116]

Have been called out to 2 boats with exactly the same problem as the OP, both times it was the batteries, both times the boats were on shoreline with the Chargers in absorption mode. After unplugging the shoreline and venting the engine bay overnight on testing the batteries they were knackered which was causing the gassing.

[IanM]

Ours went off when our batteries were knackered and gassing.

[Phil.]

Have been called out to 2 boats with exactly the same problem as the OP, both times it was the batteries, both times the boats were on shoreline with the Chargers in absorption mode. After unplugging the shoreline and venting the engine bay overnight on testing the batteries they were knackered which was causing the gassing.

 

Ours went off when our batteries were knackered and gassing.

I am rather hoping my 10 month old Trojan batteries are not knackered. They seem to hold charge very well as normal and there is no bad egg smell. Is battery gassing not a normal occurrence during charging healthy batteries?

[andyb116]

I would hope there not knackered, don't know the absorption voltage figure for Trojan batteries off the top of my head, but may be a tad high. Also if your battery box/engine bay isn't well ventilated these 2 factors could give you the problems you are getting. As an aside, when working on American RV's were they have Trojan batteries fitted under the entrance steps, they always seemed to have remote breather pipe kits fitted to the vents on the batteries.

[MtB]

There seems to be plenty of things that will set off a CO alarm other than CO.

 

There are occasional anecdotes on gas engineer forums about particularly brutal farts even setting them off. Not sure I believe them though!

[Phil Ambrose]

There seems to be plenty of things that will set off a CO alarm other than CO.

 

There are occasional anecdotes on gas engineer forums about particularly brutal farts even setting them off. Not sure I believe them though!

Huh, you've never met my dogs then.

Phil

[BruceinSanity]

There seems to be plenty of things that will set off a CO alarm other than CO.

 

There are occasional anecdotes on gas engineer forums about particularly brutal farts even setting them off. Not sure I believe them though!

I thought that was gas detectors, not CO, because the detector is triggered by any alkane gas and farts are rich in methane.

 

We've had our Trojans trip the CO alarm in the engine room when first on the shoreline, getting a bit of gassing towards the end of the absorption phase. Leaving the stern doors open sorts it. ISTR the last time this was discussed on here, someone said that the alarm trips well before the H2 reaches explosive concentration, so it's just a nuisance alarm.

[ditchcrawler]

I thought that was gas detectors, not CO, because the detector is triggered by any alkane gas and farts are rich in methane.

 

We've had our Trojans trip the CO alarm in the engine room when first on the shoreline, getting a bit of gassing towards the end of the absorption phase. Leaving the stern doors open sorts it. ISTR the last time this was discussed on here, someone said that the alarm trips well before the H2 reaches explosive concentration, so it's just a nuisance alarm.

Interesting as on 2 occasions I have had my CO detector go off in the middle of the night. on both occasions I was on a shore supply with the battery charger on. Now my charger only puts of a maximum of 4 amp but having Trojan batteries I have it set to its highest voltage.

Also some posted about an aerosol for testing CO alarms which I cant find now, Help

[Phil.]

Interesting as on 2 occasions I have had my CO detector go off in the middle of the night. on both occasions I was on a shore supply with the battery charger on. Now my charger only puts of a maximum of 4 amp but having Trojan batteries I have it set to its highest voltage.

Also some posted about an aerosol for testing CO alarms which I cant find now, Help

Is this the sort of thing your looking for.

 

http://www.gasfm.co.uk/co-detector-tester-spray-3331-p.asp

[sjc]

I know sometimes smoke alarms chirp when they are cold, this is a sign the batteries within the device are degrading. One of ours does this overnight when it is cooler, but is fine during the day. I assume this applies to CO alarms as well, do they give a full alarm, or a single chirp indicating low battery ?

[ditchcrawler]

Is this the sort of thing your looking for.

 

http://www.gasfm.co.uk/co-detector-tester-spray-3331-p.asp

Thanks for that I googled for ages

[ditchcrawler]

I know sometimes smoke alarms chirp when they are cold, this is a sign the batteries within the device are degrading. One of ours does this overnight when it is cooler, but is fine during the day. I assume this applies to CO alarms as well, do they give a full alarm, or a single chirp indicating low battery ?

Mine was 7 years old and the life is supposed to be 5. New one arrived from Amazon this morning

http://www.amazon.co.uk/gp/product/B00ABGEL62?ref_=pd_ybh_7

[MtB]

I know sometimes smoke alarms chirp when they are cold, this is a sign the batteries within the device are degrading. One of ours does this overnight when it is cooler, but is fine during the day. I assume this applies to CO alarms as well, do they give a full alarm, or a single chirp indicating low battery ?

 

 

BS-compliant CO monitors have sealed in batteries and a 'whole appliance' expiry date. The battery is designed to work well beyond the expiry date.

 

But I can't answer your question as I've never encountered one past it's expiry date yet!

[ditchcrawler]

 

 

BS-compliant CO monitors have sealed in batteries and a 'whole appliance' expiry date. The battery is designed to work well beyond the expiry date.

 

But I can't answer your question as I've never encountered one past it's expiry date yet!

The one I have just bought is I think the one recommended by the BSS for fitting on boats and has 3 dry cells in it.

Kidde 7DCO Carbon Monoxide Alarm Digital Display 10 Year Sensor and Warranty