Carbon Monoxide alarm just went off

laika

laika

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As I haven't run the engine for a few days or heater at all this year, it seems to be the batteries. A combination of having (probably) at least one duff battery, a dodgy "smart" pontoon power outlet which keeps disconnecting me and having had the fridge on all day without realising the power was off meant I was quite discharged this evening when I figured out I needed to switch the power back on. So the charger must have been working overtime and 3 hours later off goes the alarm. No sulphur smell. I presume this is hydrogen not CO so my risk is combustion rather than suffocating. I've opened up the battery compartment, disconnected the likely suspect and for good measure turned off the fridge and the battery charger. the "CO" level is now right down. Tomorrow I'll "do something".

They're sealed lead acid batteries. My likely suspect battery (one of 4 house batteries, and this is just a guess) is the closest to the load/charger, a different brand from the others (for reasons I can't recall), sounded like it was bubbling and the little window on top has no hint of green like the others do. The plan tomorrow is:
- See if the suspect has lost charge over night (not conclusive without a load, but I don't have a load tester. Better suggestions appreciated)
- Turn the fridge on and see how the remaining batteries cope
- Turn the battery charger back on and see if there's more ominous bubbling
- If everything looks "normal", replace the one battery.

Sound reasonable? Or should I run as fast as I can? I'd sleep with the hatch open but the forecast is for rain

All the batteries have had a very good innings and I should replace them all but I'm considering something fancier (possibly lithium) and I don't want to shell out £500 for lead acid batteries I'll replace next year.
 
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In my opinion your making assumptions to fit the crime. I think you can dismiss hydrogen as the cause because, having a comparatively low density it will have floated away upwards away from your CO sensor. Have you been using any aerosol products recently? They often contain gasses which are fairly dense and sink down, contaminating CO sensors. Is there any other source of possible contamination? Just because you are aware that you may have a battery problem doesn’t mean that that’s the cause for the alarm, I’d look for all likely sources before eliminating any.
Mike
 
No aerosols. (propane) oven had been on 2 hours earlier and that’s it for anything I can think of involving gas of any kind. Except the batteries. The readings on the co monitor went through the roof when I opened the battery locker and stuck it over the batteries for a bit.

I had no idea batteries could set off a co alarm but googling it there have been threads on here before (which is where the hydrogen idea came from)

co monitor is back to zero now. I’m keeping it by my bunk
 
mikegunn said:
In my opinion your making assumptions to fit the crime. I think you can dismiss hydrogen as the cause because, having a comparatively low density it will have floated away upwards away from your CO sensor. Have you been using any aerosol products recently? They often contain gasses which are fairly dense and sink down, contaminating CO sensors. Is there any other source of possible contamination? Just because you are aware that you may have a battery problem doesn’t mean that that’s the cause for the alarm, I’d look for all likely sources before eliminating any.
Mike
Click to expand...

You are correct that hydrogen will rise, but that's where your CO sensor should be, high up, because CO rises too.
 
It's fairly common for CO sensors to be set of by gassing batteries. When a cell fails short circuit the battery (if on charge) will gas and often sets CO alarms off. If your battery has a shorted cell it will read just over 10V. Hydrogen is indeed explosive, but the levels in the cabin that would set the CO alarm off are not likely to cause an issue, but be very, very careful near the batteries, a spark can cause the gassing one to explode. Once removed from charge, leave for a while to let the hydrogen dissipate before disconnecting it.
 
This may seem a bit 'off the wall' or even cheeky, but are you quite sure that it's not a low battery in the CO alarm itself that's causing the beeping?
 
laika said:
As I haven't run the engine for a few days or heater at all this year, it seems to be the batteries. A combination of having (probably) at least one duff battery, a dodgy "smart" pontoon power outlet which keeps disconnecting me and having had the fridge on all day without realising the power was off meant I was quite discharged this evening when I figured out I needed to switch the power back on. So the charger must have been working overtime and 3 hours later off goes the alarm. No sulphur smell. I presume this is hydrogen not CO so my risk is combustion rather than suffocating. I've opened up the battery compartment, disconnected the likely suspect and for good measure turned off the fridge and the battery charger. the "CO" level is now right down. Tomorrow I'll "do something".

They're sealed lead acid batteries. My likely suspect battery (one of 4 house batteries, and this is just a guess) is the closest to the load/charger, a different brand from the others (for reasons I can't recall), sounded like it was bubbling and the little window on top has no hint of green like the others do. The plan tomorrow is:
- See if the suspect has lost charge over night (not conclusive without a load, but I don't have a load tester. Better suggestions appreciated)
- Turn the fridge on and see how the remaining batteries cope
- Turn the battery charger back on and see if there's more ominous bubbling
- If everything looks "normal", replace the one battery.

Sound reasonable? Or should I run as fast as I can? I'd sleep with the hatch open but the forecast is for rain

All the batteries have had a very good innings and I should replace them all but I'm considering something fancier (possibly lithium) and I don't want to shell out £500 for lead acid batteries I'll replace next year.
Click to expand...
Five years ago my CO alarm kept sounding and discovered it was the old battery charger over-charging the batteries. I changed it for a multi-stage charger (CTEK) and have not had the problem since.

Www.solocoastalsailing.co.uk
 
PaulRainbow said:
" be very, very careful near the batteries, a spark can cause the gassing one to explode. Once removed from charge, leave for a while to let the hydrogen dissipate before disconnecting it.
Click to expand...

Some one was trying to jump start a Rib battery from a Landrover on the slip at our marina and exactly that happened . One casualty to hospital after being hit by flying debris..
 
thinwater said:
That does not prove it is the problem.
Click to expand...

Johnny Cochran could get the battery off in a criminal case but it'd lose a civil one

Low battery on the alarm was my first thought, but there's a ppm readout on the display which was high, went right down when I took the thing outside (apologies to anyone in the marina woken up late by a beeping) and went up again when I placed it over the batteries.

Thanks for all the replies. The "prime suspect" was at 10.8V this morning with the other batteries sitting at 13. However a couple of hours with the fridge on and the house bank was down to 10.9V. I know I should replace them all anyway (they've had a good innings) but I was hoping to skimp whilst planning my "next generation" power storage.
 
I had a similar experience in Leros a few years ago when faulty batteries set off the Co2 alarm. The sulphur stink was horrid and the faulty batteries were very hot to the touch.
 
Graham376 said:
Most lead acid batteries are not in fact sealed, they have a vent hole and if you rip the top label off, there's usually a flush plate (rather than filler caps) which can be prised off and the battery topped up if necessary.
Click to expand...

That used to be the case Graham, but most decent "sealed" batteries are no longer like that.
 
laika said:
Johnny Cochran could get the battery off in a criminal case but it'd lose a civil one

Low battery on the alarm was my first thought, but there's a ppm readout on the display which was high, went right down when I took the thing outside (apologies to anyone in the marina woken up late by a beeping) and went up again when I placed it over the batteries.

Thanks for all the replies. The "prime suspect" was at 10.8V this morning with the other batteries sitting at 13. However a couple of hours with the fridge on and the house bank was down to 10.9V. I know I should replace them all anyway (they've had a good innings) but I was hoping to skimp whilst planning my "next generation" power storage.
Click to expand...

From what you say the suspect battery has a shorted cell, the other others are just knackered, not holding charge. It's unlikely they died suddenly, most likely crept up on you, so it's possible you could get by on a couple of new ones for now, if you plan to fit Lithium soon.
 
One thing to take away from this is that a CO alarm is a useful piece of kit, and not only for carbon monoxide. This was a problem which needed addressing. With all the other issues I'm facing with the boat right now, batteries weren't something I was thinking about but it's good that the alarm kicked me into action rather than allowing the bad battery to bubble away gassing into the battery compartment.

With the known-bad battery disconnected, the remaining ones have been fast charging for an hour now. CO sensor is now above the battery bank registering zero and no ominous bubbling sounds. If they don't hold a charge after this I'll do what PaulRainbow suggests above: replace a couple of them and start planning the electrical re-work.
 
laika said:
One thing to take away from this is that a CO alarm is a useful piece of kit, and not only for carbon monoxide. This was a problem which needed addressing. With all the other issues I'm facing with the boat right now, batteries weren't something I was thinking about but it's good that the alarm kicked me into action rather than allowing the bad battery to bubble away gassing into the battery compartment.

With the known-bad battery disconnected, the remaining ones have been fast charging for an hour now. CO sensor is now above the battery bank registering zero and no ominous bubbling sounds. If they don't hold a charge after this I'll do what PaulRainbow suggests above: replace a couple of them and start planning the electrical re-work.
Click to expand...
At least we know you've survived the night :)
 
Laika, out of curiosity, what's the CO alarm you're using that also gives levels of CO (if i got that right?)
Only ones I've seen, and have one to install are of the simple houselike variety with a beeper and a led and that's it, either on or off!
 
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