Venting Battery Compartment

[Ted10028]

Bumped into a guy on the docks today who said my battery compartment should be vented. He said when charging a battery may produce harmful flammable hydrogen gas. It worried me a little since I have 2 big batteries when combined about equivalent in size to 5-6 car batteries. Batteries are in main cabin and next to black water holding tank. Any thoughts?
PS: how do you prevent battery overcharging?

 

[dlochner]

Venting is an issue with Flooded Lead Acid batteries, it is made worse by old battery chargers. AGM batteries rarely give off any hydrogen.

Hydrogen is the lightest element, so it will naturally rise out of the battery compartment, it doesn't need massive ventilation, just a way for the gas to rise up and out. If the batteries are in boxes, the boxes need to be ventilated. It is easier to reach an explosive level of hydrogen in a battery box than in a large space with some ventilation.

Modern three stage chargers will alleviate much of the gassing issue because they are voltage limited.

 

[kandrzejczyk]

I am using lithium ion batteries and they don’t have that problem

 

[dlochner]

I am using lithium ion batteries and they don’t have that problem

The USCG requirements for inspected commercial vessels using LFP batteries do require active ventilation and a bunch of other things. The concern seems to be dissipating heat and any off gassing from the batteries if they should get hot. The electrolyte for some Lithium batteries is flammable. The rules are oriented towards commercial vessels using electric propulsion.

 

[Ted10028]

Venting is an issue with Flooded Lead Acid batteries, it is made worse by old battery chargers. AGM batteries rarely give off any hydrogen.

Hydrogen is the lightest element, so it will naturally rise out of the battery compartment, it doesn't need massive ventilation, just a way for the gas to rise up and out. If the batteries are in boxes, the boxes need to be ventilated. It is easier to reach an explosive level of hydrogen in a battery box than in a large space with some ventilation.

Modern three stage chargers will alleviate much of the gassing issue because they are voltage limited.

thanks, do you think my 2004 Catalina 320 has a modern 3 stage charger?

 

[Davidasailor26]

thanks, do you think my 2004 Catalina 320 has a modern 3 stage charger?

Hard to say what was used originally and what it may have been replaced with by a previous owner. You’ll need to check the make and model and we can go from there.

 

[dlochner]

thanks, do you think my 2004 Catalina 320 has a modern 3 stage charger?

Who did the LFP installation? The battery charger should have been changed to one compatible with LFP batteries, along with a number of other modifications to the electrical system. LFP done right is great, LFP done wrong is a disaster waiting to happen.

As to venting, LFP batteries need venting to dissipate heat. If the BMS is senses excessive heat it will shut down the battery.

 

[Ted10028]

Who did the LFP installation? The battery charger should have been changed to one compatible with LFP batteries, along with a number of other modifications to the electrical system. LFP done right is great, LFP done wrong is a disaster waiting to happen.

As to venting, LFP batteries need venting to dissipate heat. If the BMS is senses excessive heat it will shut down the battery.

Batteries are standard flooded batteries.

 

[FastOlson]

thanks, do you think my 2004 Catalina 320 has a modern 3 stage charger?

You earlier stated that your boat has two big batteries. And you want to know what kind of charger it has.
Have you looked closely at these items? if there are no longer any labels, take pictures and post them up.

 

[dlochner]

Batteries are standard flooded batteries.

Sorry, I saw another post and that it was you who said you have lithium batteries. A photo of the charger and the batteries will help us identify them and give better advice.

 

[Don S/V ILLusion]

Perspective is important. While it is theoretically possible to accumulate H gas in a closed compartment from off-gassing , there are literally thousands of Catalinas roaming around which, for whatever reason, we’re designed to store their batteries in interior unvented compartments. I’m unaware of the statistics of how many have blown up.

 

[Tom J]

thanks, do you think my 2004 Catalina 320 has a modern 3 stage charger?

I doubt it. My 2003 C310 had a dumb charger that tended to overcharge the 4D's. At times the gas vented from the batteries set off the flammable gas alarm when the boat was closed up. I had installed a smart controller on my solar charging system, and this did a much better job of maintaining the batteries. I avoided using the dumb charger.

 

[jssailem]

Ted…
Let’s examine the issue. If batteries are over charged by their charger then there is a possibility for the fluid in the battery to reach boiling temp. When boiling the electrolyte (a mixture of Sulphuric acid and water) could break down into venting Hydrogen gas. Fortunately this gas is lighter than air and will vent away. Choosing a “smart” charger can help to not let this happen. Not charging the batteries unless you are present and making sure that there is adequate ventilation while the batteries are charging can mitigate any risk. Maintaining the water level in the batteries will help to prevent boil over. Using a smart charger with a temp sensor to shut the charger down if the battery over heats is another preventative measure.

You can manage this risk like the many boat owners have been doing for many years.

 

[dlochner]

Ted…
Let’s examine the issue. If batteries are over charged by their charger then there is a possibility for the fluid in the battery to reach boiling temp. When boiling the electrolyte (a mixture of Sulphuric acid and water) could break down into venting Hydrogen gas. Fortunately this gas is lighter than air and will vent away. Choosing a “smart” charger can help to not let this happen. Not charging the batteries unless you are present and making sure that there is adequate ventilation while the batteries are charging can mitigate any risk. Maintaining the water level in the batteries will help to prevent boil over. Using a smart charger with a temp sensor to shut the charger down if the battery over heats is another preventative measure.

You can manage this risk like the many boat owners have been doing for many years.

This is incorrect. The hydrogen gas is not produced by boiling, it is produced by electrolysis. When direct current is applied to water the bond between the hydrogen and oxygen in a water molecule is broken and oxygen, with the cathode attracting one gas and the anode the other. Bubbles form, and because the gases are lighter than the electrolyte, they rise to the surface giving the appearance of a boiling liquid.

If simply heating water (sulfuric acid is mostly water), causing it to boil created hydrogen gas we'd all be in trouble every time we made a pot of tea or pasta.

Electrolysis - Wikipedia

en.wikipedia.org

 

[JBP-PA]

Regardless of your charger, lead acid batteries should be vented. Note that batteries should be vented up, not down like propane lockers. Hydrogen rises and dissipates quickly, This makes it very easy to vent even inside the cabin. You just need to make sure there is a path for it to escape. Unless you're battery boxes/ compartment has been modified to close off the factory vents, they should already have sufficient venting.

 

[FastOlson]

Under discussion is a popular hull model made by a company still in business, with a long record of good customer service. Besides asking questions of total strangers on the 'net, just call up Catalina.

 

[Ted10028]

I doubt it. My 2003 C310 had a dumb charger that tended to overcharge the 4D's. At times the gas vented from the batteries set off the flammable gas alarm when the boat was closed up. I had installed a smart controller on my solar charging system, and this did a much better job of maintaining the batteries. I avoided using the dumb charger.

I am surprised the battery compartment is not sealed off with vents leading outside? Apparently catalina does not see it as a problem? what do

 

[Ted10028]

Under discussion is a popular hull model made by a company still in business, with a long record of good customer service. Besides asking questions of total strangers on the 'net, just call up Catalina.

I have always found their customer service nonexistent. If you have a telephone number that someone answers for service please let me know.

 

[Scott T-Bird]

My 1999 320 had a dumb charger and I replaced it (previous owner was on a mooring and never used it). It was located behind the galley bulkhead in the port lazerette. I put my new charger in the stbd side locker in the v-berth to be closer to the batteries. The boat came with two 4D AGM batts replaced in 2015 so obviously not original. I'd be surprised if your batteries are original, but not surprised if they are FLA.

So everybody understands the layout. The batteries are all located under the stbd settee in the saloon. It's a big, open space with 3 separate lids covering the 3 large openings. There is room for 2 4D batteries and a GRP 27 auxiliary battery plus a lot of space for the holding tank, hoses and whatnot. Cushions cover the lids so ventilation is very limited. The batteries sit in trays, so they are in open air within the compartment. The compartment is open to the bilge, but obviously that is lower level. Bilge covers are not vented but it is open to the compartments on the port side. I wouldn't say any of these compartments are vented, but they are relatively large open areas underneath the cushions. The area is also open to space behind the head area. There is a lot of open air underneath the furnishings.

First thing I would check is to find out what charger you have and most likely make an upgrade. If you actually have FLA batteries that are not sealed, I would think about an upgrade there, too. Obviously, I would consider the current health of the batteries.

 

[dlochner]

I am surprised the battery compartment is not sealed off with vents leading outside? Apparently catalina does not see it as a problem? what do

In normal usage, the amount of hydrogen produced is pretty minimal. Yes it it is explosive if contained in small area and exposed to an ignition source. Probably the greatest danger comes from being enclosed in an unvented battery box, In that small volume it is easy to build up an explosive level. Most of the storage compartments in our boats are not that well sealed. Once the hydrogen enters the cabin, it will quickly dissipate into the atmosphere through the natural cabin ventilation. As long as the there is an escape route hydrogen will escape.

Compared to the danger of propane and it exploding, the danger of a hydrogen explosion is next to zero.