positioning a battery in a sealed space ??

[lenten]

i have got a 15 foot outboard powered open boat with a well sealed airless front cuddy-------i want to install a 100ah battery in the cuddy----- the weight will balance the boat better ---but does a battery need ventilation??------thanks

 

[LadyInBed]

Gel or AGM will be fine without ventilation.

 

[William_H]

Probably ok with an open topped lead acid battery assuming that charge rate from the outboard engine will be quite small. Just be careful if you fast charge it from a mains charger. ol'will

 

[PaulRainbow]

i have got a 15 foot outboard powered open boat with a well sealed airless front cuddy-------i want to install a 100ah battery in the cuddy----- the weight will balance the boat better ---but does a battery need ventilation??------thanks

It should have a vent. All you need to do is to drill a small hole for the battery breather tube, making sure no water can get back down the tube. The tube needs to rise, as hydrogen is lighter than air.

I would fit an AGM battery, avoid open cell batteries.

 

[PaulRainbow]

Probably ok with an open topped lead acid battery assuming that charge rate from the outboard engine will be quite small. Just be careful if you fast charge it from a mains charger. ol'will

What happens when the OP arrives at his boat after it's been on shore power for a couple of days, with a shorted cell ? The cuddy will be full of hydrogen, one little spark and:

 

[Bilgediver]

What happens when the OP arrives at his boat after it's been on shore power for a couple of days, with a shorted cell ? The cuddy will be full of hydrogen, one little spark and:

View attachment 124519

Not only spectacular but a hospitality case if hit by the flying battery top as someone in our marina foundcout

 

[Deleted member 36384]

Not only spectacular but a hospitality case if hit by the flying battery top as someone in our marina foundcout

Did they enjoy the canapés?

 

[Bilgediver]

Did they enjoy the canapés?

Couldn't tell us as face and chin wrapped in bandages when they returned.

 

[boatmike]

I posted recently that my Moody 35 had the batteries in a closed locker under the bed. Having been involved with commercial boat and shipbuilding in a past life I have always been taught that lead acid batteries should be in a vented compartment to stop hydrogen build up. In fact Lloyds have insisted on it. I got a mixed reaction from others though saying in effect "don't worry about it" and I do reflect that Moody 35s were built to Lloyds standard reputedly? Nevertheless I intend to vent the underbed space to atmosphere with the addition of a small grille as suggested by another member. Don't think it requires a lot but I still think totally closed compartments is a bad idea. Can't hurt and just might avoid a possibly catastrophic situation even if it is an unlikely event.

 

[Momac]

I am sure many boats have a bow thruster or anchor winch battery located in a space that is not ventilated directly to the outside air , like under the floor of the front cabin .
The boat safety scheme for inland waterways craft allows a sealed type battery in such a space.

 

[PaulRainbow]

I posted recently that my Moody 35 had the batteries in a closed locker under the bed. Having been involved with commercial boat and shipbuilding in a past life I have always been taught that lead acid batteries should be in a vented compartment to stop hydrogen build up. In fact Lloyds have insisted on it. I got a mixed reaction from others though saying in effect "don't worry about it" and I do reflect that Moody 35s were built to Lloyds standard reputedly? Nevertheless I intend to vent the underbed space to atmosphere with the addition of a small grille as suggested by another member. Don't think it requires a lot but I still think totally closed compartments is a bad idea. Can't hurt and just might avoid a possibly catastrophic situation even if it is an unlikely event.

As i said in the thread you refer to, being beneath a bunk or a sofa isn't necessarily a sealed space. My batteries are beneath a saloon sofa, but if the gas, the Co alarm in the aft cabin goes off, so definitely not an airtight space.

The OP here describes a "well sealed airless front cuddy ", if that's the case, it needs ventilation.

 

[PaulRainbow]

I am sure many boats have a bow thruster or anchor winch battery located in a space that is not ventilated directly to the outside air , like under the floor of the front cabin .
The boat safety scheme for inland waterways craft allows a sealed type battery in such a space.

In which case the BSS is flawed (no surprise there i guess).

If the space isn't airtight (typical under bunk space) then standard wet cell batteries will be fine, any hydrogen can escape. If the space is airtight, a sealed lead acid battery can still gas, vent hydrogen and with the aid of a spark, explode.

 

[Momac]

If the space isn't airtight (typical under bunk space) then standard wet cell batteries will be fine, any hydrogen can escape.

That's more or less what I have but I would not like to say gas can escape freely and certainly it cant escape freely directly to the outside air. The area where the bow thruster battery is located in a bilge area under a lift out floor panel and the area is connected to an adjacent fairly large bilge area.

 

[lenten]

thanks for all replies been helpful-----the basis for this enquiry was me blowing up a battery whilst charging on a car many years ago---- my 15 hp yamaha has a very low charging rate and any faster charging will be done in a barn with the cuddy open-----an open boat can be very wet-----spray/rain or both so i can t think of any practical way to vent without some dampness getting into cuddy-----there will be no switches in cuddy so no sparks??---on balance i think i will position battery in cuddy and open hatch to ventilate when possible

 

[Buck Turgidson]

What happens when the OP arrives at his boat after it's been on shore power for a couple of days, with a shorted cell ? The cuddy will be full of hydrogen, one little spark and:

View attachment 124519

That battery appears to have a vent pipe connected.