Carbon Monoxide Alarm - Battery Dead

[Grubber 12]

Keen to learn from the chemists/technical or battery experts out there.

Loaned the caravan to my daughter for the weekend. When it was returned MM was playing up, checked battery voltage and it was11v. Plugged in 240v, all was fine. Thought little more of it. Perhaps daughter had unplugged EHR early onsite and drained battery a tad. Next morning I could hear the Carbon Monoxide (CO) alarm kicking off. The alarm was close to its 7 year expiry so thought little more of it. Just opened the rooflight (just to be safe). That evening I turned off the gas supplies just to be sure nothing was burning. Next day, mid morning, CO alarm kicking off again. I checked the battery compartment; the battery felt warm but nut not hot. I phoned Fire angel and explained the situation and they explained that my CO alarm was a duffer. Whilst googling to find a replacement CO alarm I noticed that the alarm was reading 0ppm inside my house. This led me to think that perhaps the CO alarm was actually working correctly. Used different CO alarm from house in caravan and to my shock it also kicked off. Replaced leisure battery. No further problems.

There were no smells coming from the battery. The old battery since checked by the local garage who confirmed it was knackered. There were no other technical indications that anything was wrong once plugged in to EHU. So my question is: could we have been in danger had we used the caravan without a functioning CO detector? And also (one for the chemists or battery experts) why is a knackered battery giving off CO when being charged.

 

[Buckman]

Rather safe than sorry. I think there was a big fire somewhere recently and it may have started due to a duff battery? No one knows.

 

[RogerL]

Batteries can fail for a number of reasons - a conventional lead-acid battery has 6 cells, if it's failed because 1 cell out of the 6 has failed the voltage will drop causing the on-board charger to continue charging - but that will be over-charging the other 5 cells which will give off the gases - now the battery compartment should be sealed from the caravan interior but sometimes that sealing fails and some batteries aren't in a sealed compartment.

 

[Woodentop]

Batteries usually give off a number of gases under charge and the CO alarm is sensitive to more than CO alone.

 

[ProfJohnL]

I am really surprised that a failing battery was able to pollute the living space with gasses. This makes me suspect you don't have a battery box in the external side wall of the caravan. Is this and old caravan.

 

[Grubber 12]

I am really surprised that a failing battery was able to pollute the living space with gasses. This makes me suspect you don't have a battery box in the external side wall of the caravan. Is this and old caravan.

Battery box is on the outside.

 

[Grubber 12]

On checking, i notice there is a cable gland that has come adrift. So the battery box was not completely hermetically sealed from the caravan.

 

[Mel]

I am really surprised that a failing battery was able to pollute the living space with gasses. This makes me suspect you don't have a battery box in the external side wall of the caravan. Is this and old caravan.

Curiously, I have seen more than a couple of reports across some FB groups I frequent ☺️, about a cooking battery setting off the internal CO alarm. I can only assume that the CO alarms are sensitive to the merest whiff that works its way in. Grubber’s report is by no means unique. Over to you for the possible science.
Mel

 

[Grubber 12]

Thanks for the input. I did say in my OP that I was hoping from some input from a battery expert or chemist. Does one expect a duff battery, under charge, to give off CO?

 

[RogerL]

When we bought our present caravan we had the dealer swap our old motor-mover onto the then new caravan - once the warranty had expired we switched to using a mobile AWS for servicing who picked up that the cables added for the motor-mover hadn't been sealed so there was the possibility of battery gases leaking into the inside of the caravan - he then fixed the issue with copious amounts of silicone sealant.

 

[Gafferbill]

Does one expect a duff battery, under charge, to give off CO?

......Lead acid batteries can give off Hydrogen when being charged especially if they are failing.
Carbon Monoxide alarms can also detect Hydrogen.

 

[JTQ]

Thanks for the input. I did say in my OP that I was hoping from some input from a battery expert or chemist. Does one expect a duff battery, under charge, to give off CO?

The simple direct answer to that is "no", CO is not involved here.

That said, there can be other serious risk factors other than CO involved in attempting to charge lead acid batteries with various failure faults.
Way better not to try, and of course if it has a fault, it's pointless trying anyway.

I don't claim to be specifically an expert in this field, but a practicing engineer for many decades some of it involving LA batteries, "one" picks up a level of understanding of them.

 

[otherclive]

Thanks for the input. I did say in my OP that I was hoping from some input from a battery expert or chemist. Does one expect a duff battery, under charge, to give off CO?

As Gafferbill says CO detectors can cross sense hydrogen. Here’s info from Drager experts in gas sensing technology. If you battery box was not sealed into the caravan there could be a leakage path.

https://www.draeger.com/Content/Documents/Content/hydrogen-application-info-wp-pdf-10994-en-master.pdf

 

[ProfJohnL]

Thanks for the input. I did say in my OP that I was hoping from some input from a battery expert or chemist. Does one expect a duff battery, under charge, to give off CO?

This is a caravanning forum and whilst there may be a "Battery Expert" who caravans and might read this forum, I honestly think if you are looking for a chemical analysis I think you should really be asking on a chemistry or battery site.

Whilst many of us may have an opinion about what has happened, the fact this is a an anonymised forum, you have no way of verifying if the information provided here is accurate or should be believed. For information of the detail you seem to be seeking, you need to contact a verifiable expert.

From a practical point of view, the battery box should be room sealed to prevent any gasses of fluids from entering the living space. There is some doubt as to whether the battery was producing CO, or whether it was another gas that the CO monitor responded too. Either way that gas should not have gained access to the living space. As I pointed out before the external battery boxes should be fitted to provide a means of external ventilation to allow any gases to escape outside.

All batteries use chemical processes to operate. Depending on the materials and construction of the battery, they can produce gasses. Generally it will be when they are charging, but it could also arise when they are supplying current. Lead Acid batteries are known to be able to release hydrogen gas if they are overcharged. Hydrogen is the lightest known gas which means its will naturally rise to the highest point, and it has the smallest atomic size which makes it able to pass through some materials that you might consider to be impervious. It is also highly flammable, which is why Lead Acid batteries should not used in enclosed living space like caravans, hence the room sealing I mentioned above.

Another reason for room sealing, is that if a battery is producing hydrogen, usually from a damaged cell, and the fact H is high flambale even explosive, if the hydrogen is ignited ic can literally cause a battery to crack open or explode! If this happens you don't want the sulphuric acid in the battery from splashing all round a caravan. its far better to contain it the battery box.

 

[Gafferbill]

Just for the record ......
my post in this thread contains facts which can be readily verified by conducting an Internet search of industrial expert companies who make CO detectors.
If I give an opinion I preface it with "IMO"

 

[otherclive]

Just for the record ......
my post in this thread contains facts which can be readily verified by conducting an Internet search of industrial expert companies who make CO detectors.
If I give an opinion I preface it with "IMO"

The link to Drager in my post #13 references one such expert company whose products and systems have been used widely in industry and defence fir many many years.

 

[otherclive]

The OP may be interested to know that several boat owners have had similar experiences put diwn to battery issues.

CO alarm and unusual battery condition

I got to the boat last night to find the carbon monoxide alarm beeping. It showed a value of 125 and ok battery. Removing it from the boat stopped the alarm so I think the detector was ok. I disabled the alarm, closed the forepeak door, opened the fore peak hatch and went to sleep in the...

forums.ybw.com

 

[Martin_E]

It’s fairly common for duff batteries to set off CO alarms. Don’t forget a battery box isn’t sealed to the outside, gasses can vent externally, caravans have drop holes and lower ventilation and the gases can enter the van through them if the conditions are correct.

Also like an lpg leak in the front locker or in a Bailey a side locker can sometimes be smelt internally, wind etc in the right direction will puff it up through the vents. I speak from experience of this, so no I can’t direct you to where this is documented on the internet as I haven’t looked 🤔

 

[otherclive]

I suspect that we are now talking amongst ourselves 😂