Ventilation of Battery Compartment

[davisr]

Thanks Gord for pointing out that it is Yandina Marine Electronics that manufactures battery compartment ventilation fans specifically for boats. From what I can tell from searching around the internet, Yandina is the one of the few (if not the only) company in this niche. Google searches for "battery compartment ventilation" and similar searches usually bring up about four different types of results:

1. The present discussion on Cruisers Forum and the earlier posts on this subject from 2006 (the one Gord initiated).

2. Discussions among U-Boat and submarine enthusiasts about how flooded cell batteries used to be ventilated under the sea. Interesting. Cool drawings. Damn, those were some huge battery banks.

3. Products for use in the solar and transportation industries

4. Urgings by the US Coast Guard and other official voices that it is necessary to vent battery compartments when charging flooded cell batteries. No references, though, on how to vent.

It seems, then, that Solitude, Blue Stocking, and James S are on to something when they suggest that most cruisers don't bother to vent battery compartments with flooded cells. It seems that if venting were the norm, and there were a big demand for battery compartment venting systems, then there would be a variety of marine-related products out there and a variety of discussions about them on this forum.

It is hard, though, to ignore what Gord said at the beginning of this discussion, and I quote him here:

"ABYC E-10.7.10 states:
A vent system, or other means, shall be provided to permit the discharge from the boat of hydrogen gas released by the battery."

Does this mean that builders and surveyors tend to look the other way when it comes to this rule?

Thanks,
Roscoe

[James S]

Originally Posted by davisr

Does this mean that builders and surveyors tend to look the other way when it comes to this rule?

Thanks,
Roscoe

So do production boats vent to the outside?
If so who and how do they do it.

[S/V Antares]

Just Curious!!--how many of you REALLY think your boat meets the relevent ventilation specs to which these valuable posts refer.

Avisor, Good question. I do not currently have a vent system but after reading the thread (even the menutia) I will be adding one to the battery bank in my seat locker. Just to keep dock lines, sponges and other assorted items intact.

[Stillraining]

If venting as per a calculation I remember Gordy doing some time ago about concentrations needed for a Hydrogen explosion..It seems that venting like James does to a larger volume area of the boat that can or does eventually escape through less then air tight confines as any boat i have ever been aboard surly is...will eliminate the explosion risk to virtually zero..no?..also....is there really a health risk in a small amount of Hydrogen intake in the volume we breath of say a 40'boat..?

Now if your equlizing i definetly see a need to have a very open boat to aid exhaust but not so convinced under normal usage.

Now if you smoke your coments of concern will be severly prediguest against by me, so be forwarned...

Just asking honest questions.

[Roy M]

The health risk (beyond explosion of hydrogen) might actually be more due to the sulfuric acid vapor from the electrolyte. That's what is actually charring the inside top of plywood battery boxes or other vulnerable surfaces in a contained space.

[sailvayu]

Just a note in all this, ABYC makes no distinction between wet cells and AGM as far as installation regulations go. So any argument about what batteries vent and what do not is mute. The recommendations apply no matter what battery is installed. The rational is that it is possible the AGM could be replaced with a wet cell at any time, therefore the installation must meet the recommendations for wet cell period. I have discussed this with ABYC headquarters, there are no questions far as they are concerned. The recommendations apply no matter what battery is installed.

Wayne Canning, AMS
projectboatzen.com

[davisr]

Based on several different google searches that I have done with key words such as "battery explosion boat" and "battery explosion sailboat," it appears that battery explosions were a major concern during the WWII era. There were quite a few US subs that sunk for this very reason. See
U.S. Submarines Lost through Enemy Action and through Accidents

Then I found this discussion on the Hull Truth titled "What really causes a battery to explode?" What really causes a battery to explode? - The Hull Truth

Also I found this case report of an accident that occured at a boatyard in Calfornia: NIOSH FACE Program: California Case Report 07CA004 | CDC/NIOSH

It seems that in the Hull Truth discussion and in the California accident report there is an over-arching theme: manual connection of jumper cables or charging cables are a common culprit. Sparks ignite the gasses. Another issue sometimes in the mix is charge-rate.

[Stillraining]

Yep...this why you always connect the jumper cables to the dead bat. first or remove them from the just jumped battery last..So your not doing it with charged jumper cables eliminating any spark potential.

[Morganministry]

Originally Posted by Roy M

The health risk (beyond explosion of hydrogen) might actually be more due to the sulfuric acid vapor from the electrolyte. That's what is actually charring the inside top of plywood battery boxes or other vulnerable surfaces in a contained space.

I believe that is actually Hydrogen Sulfide gas. Nasty stuff. You do not want to breath it.

Scott

[Not Sure]

Originally Posted by Stillraining

Yep...this why you always connect the jumper cables to the dead bat. first or remove them from the just jumped battery last..So your not doing it with charged jumper cables eliminating any spark potential.

As an addition to the above, the correct procedure to hook up a battery is to always connect the positive(+, generally red cable) side of the battery first. Then connect the negative(-, generally black cable) side.
To remove the connections you do so in the reverse order, i.e. remove the negative(-) side first, then remove the positive(+) side last.

Also, it's not that you entirely eliminate sparks in this method, but rather that you mitigate or minimize the sparks or potential for sparks, thereby minimizing the chance of ignition of any explosive vapors. (You'll usually still get a small spark when connecting the (-) terminal after the (+) terminal, for example, but nothing near the sparking that is present if you use the (+) terminal to complete the circuit.)

[Roy M]

Originally Posted by Morganministry

I believe that is actually Hydrogen Sulfide gas. Nasty stuff. You do not want to breath it.

Scott

Sorry, Scott, that's not part of the chemical reaction or environment of a battery gas discharge. Holding tanks give off H2S, not lead-acid batteries. Here's a confirmation source: The Basic Chemistry of Gas Recombination in Lead-Acid Batteries

The sulfuric acid in the electrolyte can be carried out of a flooded battery (as well as sealed) in a vapor state, un-ionized. It's even nastier than H2S because it begins corroding tissue on contact.

[cal40john]

Originally Posted by Not Sure

As an addition to the above, the correct procedure to hook up a battery is to always connect the positive(+, generally red cable) side of the battery first. Then connect the negative(-, generally black cable) side.
To remove the connections you do so in the reverse order, i.e. remove the negative(-) side first, then remove the positive(+) side last.

Also, it's not that you entirely eliminate sparks in this method, but rather that you mitigate or minimize the sparks or potential for sparks, thereby minimizing the chance of ignition of any explosive vapors. (You'll usually still get a small spark when connecting the (-) terminal after the (+) terminal, for example, but nothing near the sparking that is present if you use the (+) terminal to complete the circuit.)

Doesn't matter which side you connect first, you can get sparks. On cars most everything is ground which is why the procedures exist, and what they have you do is connect and disconnect the negative on the car frame away from the battery. To accomplish the same on a boat you would need to break or make connections the first place your mains are attached to something else.

John

[dkirby_jwa]

I just curious what the guys that sell the electric propulsion systems would say about this? Electric Yacht - Electric Yacht: Electric sailboat auxiliary systems that are Cost-Effective, yet CLEAN, GREEN and QUIET
Seeing as how most of the installs that I see on the links and there websites replace engines with batteries in the same compartment and nothing is mentioned about vents. Some of these installs are 8 ~ 12 volt batteries.

[davisr]

Good point. The website suggests that 6V flooded cell batteries be used and that they be stored in the quarterberth or engine compartment. No mention of ventilation. Guess they don't want to bring up the subject of ventilation, but seems that they would want to mention this for liability purposes. Probably in the fine print once you buy it.

I still keep thinking that passive ventilation of battery compartments is the norm - especially since Yandina Marine Electronics appears to be the only company that makes venting fans specifically for personal watercraft, and since there are so few discussions out there of how to vent a battery compartment.

The Electric yacht motor company would probably tell you in the fine print that you must vent your battery compartment, but then not tell you how to do it. This is what other companies seem to do. It's what the Coast Guard does and apparently the ABYC as well.

Maybe it's the lack of specifics that lead most people to passively vent their batteries, hope for the best, and spend their money on things other than venting fans, etc.

That's just my guess based on everything I've read.

[Morganministry]

Originally Posted by Roy M

Sorry, Scott, that's not part of the chemical reaction or environment of a battery gas discharge. Holding tanks give off H2S, not lead-acid batteries. Here's a confirmation source: The Basic Chemistry of Gas Recombination in Lead-Acid Batteries

The sulfuric acid in the electrolyte can be carried out of a flooded battery (as well as sealed) in a vapor state, un-ionized. It's even nastier than H2S because it begins corroding tissue on contact.

Thanks, That was my bad. you are right.

I was thinking of H2SO4 which is sulfuric acid and not Hydrogen sulfide.
Its been a while since I've had to think about chemistry.

Either way, you don't want to breath the vapors.

Thanks,
Scott