Hydrogen detection

Tigelowe · May 2016

Hello,

Is anyone using a hydrogen detection device to turn on a vent fan in their battery room? My batteries and electronics are in an 8'x12' well house. The well house is close to air tight. I will usually open the door during the absorption stage but I am not always home to do so. I have 16 Trojan 370AH batteries charged by 3KW of solar.

The cost of a hydrogen detector is steep at around $1000. I'm looking at the 'SBS-H2' and 'HGD-2000'.

Any other ideas to control hydrogen would be appreciated.

Thanks,

Joe

mike95490 · May 2016

I built my battery shed with open eves to vent hydrogen, I think the detectors also have a 6month life on the sensor elements, we always had false alarms and installed new elements to silence them.

You can use a simple voltage sensor to sense the absorb voltage and trigger a vent fan from that.

vtmaps · May 2016

Hydrogen is hard to contain... it's much lighter than air, and a passive vent at the high point of the well house will allow it to escape.

Are your batteries exposed? If so, that is an improper installation... electronics should not be in the same room with exposed batteries. The batteries should be in a box. The box should be vented to the outside of the well house.

The conduit with the battery cables should enter the battery box below the tops of the batteries... hydrogen rises and will not enter the conduit.

By the way, keeping your electronics away from exposed batteries is not just about hydrogen... sulfuric acid mist emanates from your batteries and can be a corrosive influence on your electronics and wiring (and your nasal cavities).

What controller do you have? ... some controllers have a voltage controller aux output that can power a small fan.

--vtMaps

Ralph Day · May 2016

I had a hydrogen detector years ago. It would get polluted and sound quite often. My battery box is power vented all the time (not just via vent fan aux).

I'd suggest you box the batteries and passive vent them, don't forget to install an inlet vent too.

Tigelowe · May 2016

Thanks Mike, VT, Ralph,

I will box the batteries and passive vent the box.

-Joe

Mangas · May 2016

I have a hooded DC air extraction system.

The CCs' and AGS' energize the two DC fans installed over the battery banks when voltages are in higher ranges. Air is exhausted from the solar mechanical room to the outside.

Works great.

simmtron · May 2016

My propane detector seems to work as a hydrogen detector in my RV. During the day when the batteries were charging in the "basement" compartment and all the windows were close my propane detector would go off. I fixed this by cutting a hole in the door of the battery compartment and installing and installing a 2 1/2 inch computer fan that is directly connected to a small solar panel. Whenever the sun is up the fan starts and vents the compartment. No more Propane alarm.

zoneblue · June 2016

With an arduino and little soldering, you could try something like this:
https://www.sparkfun.com/products/10916

However batterys gas at fairly predictable times, and you ought to be able to just use something from your controllers AUX system, that triggers on voltage or charge stage.

WaterWheel · June 2016

I programed my charge controller to turn on a little relay I installed when the battery voltage is above 53.5v. My inverter has the same ability.

My vent fan runs on 48v and the signal the charge controller and inverter send is only 12v thus the relay.

ramloui · June 2016

To keep things in perspective, I looked at the flammability and explosion limits (4% and 18.3% respectively) for hydrogen. I computed that to attain a dangerous mixture of hydrogen in air in a 8' x 14' enclosed area (assumed 8' ceiling) you would need to decompose about 0.6 kg of water for a flammable atmosphere or 2.6 kg of water to get to an exploseve atmosphere. That is quite a quite a lot of water.

How much time would be needed to decompose all that water at the charging conditions? I don't know but you should also consider that as the hydrogen is being evolved, some is escaping the building at a rate that depends on its tightness.

So, look at the rate at which you add water to your batteries. That is the amount of water that turned to hydrogen (and oxygen). If you add less water to your batteries every time you go check on them (thereby opening the door and letting a lot of H2 escape...), I would not worry about it.

Cheers!

vtmaps · June 2016

ramloui said:
To keep things in perspective,
<snip>
I would not worry about it.

I tend to agree with your analysis... but I acknowledge that people have been seriously burned and injured by hydrogen (from a battery) explosions. I wouldn't downplay the dangers of hydrogen just because I believe my own analysis.

--vtMaps

ramloui · June 2016

vtmaps said:

I tend to agree with your analysis... but I acknowledge that people have been seriously burned and injured by hydrogen (from a battery) explosions. I wouldn't downplay the dangers of hydrogen just because I believe my own analysis.

--vtMaps

Yes, agree completely. You have to be aware of your specific circumstances: a battery box is a different analysis and, at any moment in time, concentration of hydrogen is highest where it is emitted... near the battery. Create a spark and kaboum.

Dave Angelini · June 2016

You do have to design for the bozo factor sometimes. I try and screen these future clients to the other solar guy. Agree with both of you that for average people in decent size rooms that I have never heard of a Kaboom. Anyway stay clear of these folks in the attachment and have a good week-end!

Hydrogen detection

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