New batteries triggering gas alarm???

[Oscarpop]

We have a haztec gas alarm with the sensor next to the floor panel that holds out batteries.
We changed the batteries today from sealed to wet.
Since then every time I lift the floor panel the gas alarm goes off.
The gas is isolated and we have never had this problem before in 4 years of owning the boat.
Any ideas?
I thought th e detector just detected cooking gas and not vapour from batteries .

 

[Mistroma]

Carbon monoxide and gas sensors are sensitive to hydrogen. The level of sensitivity depends on the type of sensor but it has been commented on frequently in this forum in past years. I think that some brands can be much more sensitive to hydrogen than carbon monoxide and will be triggered when close to a charging lead acid battery. Same is probably true of gas sensors.

 

[sarabande]

If the Haztec is set up to detect LPG, then hydrogen will also trigger it. I am surprised that your batteries are producing so much hydrogen*, but Seath's specification will tell you how many ppm (parts per million) the system will find.

https://www.youtube.com/watch?v=m3dAFInO7i0


Any other sources of flammable gas ? Repainting or varnishing with a high solvent paint ? Methane from biological activity in the bilge ?


Or even, you might have an LPG leak.


*normally it will just float upwards to atmosphere, but if the battery compartment is pretty well sealed, the gas could be retained in bulk; in which case you need to get some ventilation in there.

 

[bitbaltic]

I flattened a big house battery last season which killed it. Not knowing this I put it back on charge and it didn't stop charging, started cooking, and set off the CO alarm (domestic type). Also have the haztec (sensor lower down than the batteries) which is set up for LPG, not CO, and did not go off.

After eliminating an LPG leak I would be a bit concerned about what you might be doing to those batteries.

 

[sarabande]

After eliminating an LPG leak I would be a bit concerned about what you might be doing to those batteries.

Just wondering if the charger is set for "Sealed" instead of "Standard", or similar. Hence possible overcharging.


Any voltage readings, Oscarpop ?

 

[GHA]

If the Haztec is set up to detect LPG, then hydrogen will also trigger it. I am surprised that your batteries are producing so much hydrogen*.

My alarm will go off as well when charging if they are on absorption for a while. But even the gas soldering iron will set it off, very sensitive devices.

 

[Oscarpop]

Batteries are new today .
Trojan t105s.
Voltage is 13.1v which was the same as the last .
It could be a go as leak, but it would be some coincidence.
No gas leaks in 4 years. Gas isolated for n 2 hours , and as soon as I fit the batteries it goes off when I lift the floor.

Also checked the charger . No mods needed for wet batteries . Master volt mass.combi.

If other forumites have a similar reaction with the same sensor, then I'll take it as hydrogen
Chwers

 

[Mistroma]

Batteries are new today .
Trojan t105s.
Voltage is 13.1v which was the same as the last .
It could be a go as leak, but it would be some coincidence.
No gas leaks in 4 years. Gas isolated for n 2 hours , and as soon as I fit the batteries it goes off when I lift the floor.

Also checked the charger . No mods needed for wet batteries . Master volt mass.combi.

If other forumites have a similar reaction with the same sensor, then I'll take it as hydrogen
Chwers

It does sound as if it is the batteries as the gas was isolated for hours and alarm still triggered when battery cover lifted plus batteries are brand new.

You say that no mods. needed for your charger but float is giving 13.1V. Trojan suggest 14.8V tapering to a 13.2V float. I believe that some T105s may now use Trojan's Smart Carbon™ technology and did see 13.5V float in one recent document.

It would be worth checking the correct settings in case you have one of Trojan's newer T105s. Also pretty common for chargers not to be set to reach 14.8V during daily recharge. I read a report a few years ago where one user reported improved performance and longevity after setting his charger to Trojan's preferred figures.

 

[Lon nan Gruagach]

You might test for hydrogen sensitivity by making some* and pouring it (upwards) onto the sensor.

In a bowl of water place 2 wires with an inch of stripped insulation. Place a water filled upturned jar over each stripped wire end. Apply low voltage dc to the wires. One jar will fill with oxygen, the other hydrogen.