Ideas for ventilating battery compartment

[slowpoker]

Batteries need to be cool and ventilated from the explosive gasses they generate, specially the flooded types; therefore the engine compartment is not the best place.
If you have an enclosed compartment, how would you ventilate it? Or do you?
A small intake grill on the cabin side to suck in cool air while a small computer fan blows it towards the engine compartment through a hole in the bulkhead?
What if that fan blowing is then, inside a flexible duct, directed towards the alternator to keep it cooler also, but with the danger of igniting those explosive gasses from the batteries?.
Or the fan blowing into the duct, towards the outside of the vessel like a bilge blower which makes another hole for water to come in ?.
If this venting duct is combined with the existing bilge blower duct hole, some of this air/ gas mixture will settle down the bilge duct into the engine's compartment and deep bilge anyway, so why bother doing that.
The batteries could be charging from several sources; shore power battery charger, engine alternator and even solar panels and wind generator, which is my case for 6 batteries in that enclosed box space.
In all these cases, the batteries would benefit from being ventilated since they will generate heat and gasses while being charged.
What other ways you ventilate your batteries?
Many electronic gadgets reside near batteries in most boats and that is the case in this compartment.
Things like monitoring gauges, Ammeters, Voltmeters, ACR, also 1-2 both switches, other switches, buss bars, shunts, fuses and many connections that will corrode faster if all those corrosive gasses are present.
What do you do to try to avoid explosion, heat and corrosion?

[TeddyDiver]

Battery ventilation should be separated from other compartments. Hydrogen gas is lighter than air so it doesn't settle in the bilge. Battery Room Hydrogen Gas Ventilation Calculator by SBS Battery

[UNCIVILIZED]

Wow, I used the calculator & am amazed at how much ventillation is recommended. Especially when figuring for just one battery. Since due to some of the hydrogen demo's I've seen, it's tempting to treat the stuff pretty casually. Oops.

To the OP, might you rig up a powered ventillation system in the manner of an eductor? That would create good, continual air flow, without the fan's motor being in direct contact with the air from the compartment if done right. At least in theory. Though I've never seen nor heard of using such a system to ventillate battery compartments.

A blower rated for such environements could be an option. Though there still might be some small margin of danger present from the perspective that moving air creates static charges. Time for some studying on this.

[Dockhead]

You can't vent hydrogen gas except straight up. It is far lighter than air and is the least viscous substance on earth and so you cannot hold it or direct it with ducts or anything. You should just forget about hydrogen gas -- it is not a problem. It is gone almost instantly.

The reason for venting batteries is not hydrogen, but hydrogen sulfides and other stinky byproducts of the chemical processes; also to help keep them cool.

My boat has blowers to vent the battery boxes. Like engine room ventilation, they run whenever engine or generator is running or high temp in the boxes. Air is drawn in from the bilge and exhausted through the transom.

[TeddyDiver]

Hydrogen explosion is defineatly a risk. Not a high propabilty one but if it happens it can be destroy a boat quite badly so not to be taken lightly. To avoid one having no connectors of any kind in the battery compartment and good ventilation are essentials. Note the size of the battery compartment has no effect on the fan requirement but the over loading does.

Might consider battery vent tube instead?

BR Teddy

[Dockhead]

Originally Posted by TeddyDiver

Hydrogen explosion is defineatly a risk. Not a high propabilty one but if it happens it can be destroy a boat quite badly so not to be taken lightly. To avoid one having no connectors of any kind in the battery compartment and good ventilation are essentials. Note the size of the battery compartment has no effect on the fan requirement but the over loading does.

Might consider battery vent tube instead?

BR Teddy

Just make sure there's nothing which can catch and hold the gas. There should be small vent holes in the top of the battery boxes.

"Hydrogen has been portrayed in the popular press as a relatively more dangerous fuel, and hydrogen in fact has the widest explosive/ignition mix range with air of all gases except acetylene. However this is mitigated by the fact that hydrogen rapidly rises and disperses before ignition, and unless the escape is in an enclosed, unventilated area, [the risk] is unlikely to be serious."

https://en.wikipedia.org/wiki/Hydrogen_safety

[Snowpetrel]

https://youtu.be/d_TnsHu2u4c

Sent from my SM-G930F using Cruisers Sailing Forum mobile app

[GordMay]

Originally Posted by Dockhead

.. and unless the escape is in an enclosed, unventilated area, [the risk] is unlikely to be serious."

Like a typical battery box.

[Dockhead]

Originally Posted by GordMay

Like a typical battery box.

??

Mine have blown ventilation, plus small holes in the top to let out hydrogen. I don't know about others, but Moody did it right.

I wonder what ABYC say about it?

[masonc]

Don't use a computer fan to vent hydrogen, it won't be explosion rated and you may cause an explosion instead of cure it. In solar,we use battery box vent fans that are switched on by the charging inverter to vent the gassing. Batteries only gas when being charged aggressively. You don't want the fan running all the time.
https://www.altestore.com/store/deep...ilation-p2287/
If your charging source is solar, then a fan driven by a small solar panel would probably work very well.

[masonc]

You can use a Simple Switch device to control the fan.
https://www.altestore.com/store/encl...ve-high-p1400/

[GordMay]

Originally Posted by Dockhead

... mI wonder what ABYC say about it?

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

[GILow]

Originally Posted by Snowpetrel

https://youtu.be/d_TnsHu2u4c

Sent from my SM-G930F using Cruisers Sailing Forum mobile app

I dunno mate. I suppose that shed would fit on the foredeck but it is gonna play merry hell with our windward performance and I think it might foul the staysail.

[GILow]

Originally Posted by masonc

Don't use a computer fan to vent hydrogen, it won't be explosion rated and you may cause an explosion instead of cure it. In solar,we use battery box vent fans that are switched on by the charging inverter to vent the gassing. Batteries only gas when being charged aggressively. You don't want the fan running all the time.
https://www.altestore.com/store/deep...ilation-p2287/
If your charging source is solar, then a fan driven by a small solar panel would probably work very well.

I would assume the "proper" fans are brushless to avoid creating sparks.

But I would go to great extremes to avoid creating a system that depended on the fan to provide ventilation since the fan would be prone to failure and present an additional risk to the boat. Passive systems first, there are plenty of good diagrams on the world-wide-wait.

[kas_1611]

Originally Posted by masonc

Don't use a computer fan to vent hydrogen, it won't be explosion rated and you may cause an explosion instead of cure it. In solar,we use battery box vent fans that are switched on by the charging inverter to vent the gassing. Batteries only gas when being charged aggressively. You don't want the fan running all the time.
https://www.altestore.com/store/deep...ilation-p2287/
If your charging source is solar, then a fan driven by a small solar panel would probably work very well.

And everything on your boat is EX or EEX rated? All those cable connections, electrical gizmos, switches etc?