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Palarran · 16-10-2018, 09:51

I'm thinking about relocating my battery bank from the stern of the boat to a spot under floor boards in a forward berth area. Possibly even under the berth itself. I know the batteries gas when charging if lead acid and that would need to be addressed. Is there anything obvious about locating a large house bank in this area?

mikedefieslife · 16-10-2018, 10:38

Flooded lead acid batteries give off hydrogen gas, you’d want good ventilation. Normally you wouldn’t want what is the heaviest item on the boat, anywhere near the bow.

ranger58sb · 16-10-2018, 11:16

It could be a good application for sealed valve-regulated AGM batteries... if your situation can deal with the rest of the typical AGM requirements.

And/or depending on your target voltage, Firefly Carbon Foam AGM batteries bring the advantages of being sealed and valve-regulated, but they're said to be better in a usually-PSOC (partial state of charge) environment.

There are lots of threads about pros/cons of AGMs, and Maine Sail's "marine how to" website goes extensively into it too...

-Chris

hellosailor · 16-10-2018, 11:22

Even AGMs can outgas, so they still need to be vented overboard.

Running any battery forward may be problematic, because you're going to need pricey thick cables with low voltage loss to connect them back to the charging source and distribution panel in the stern. Pricey, and often a nuisance to run.

**JPA Cate** · 16-10-2018, 12:51

Also, if they are FLA batteries, they are heavy. Their present location is where the designer thought that weight should be, perhaps the boat is even strengthened there to support them, but it is also the shortest run, with least voltage loss.

Ann

Palarran · 16-10-2018, 19:05

This situation is a little different as the thick heavy wire right now is running from the stern about 50' forward to my 12v distribution panel. By moving them the lead wire would be about 8'. It's also still about 14' back from the bow. My sterns are very heavy due to extra equipment installed in the aft compartments. This would definitely help with the balance of the boat and also move the weight lower in the hull. Access is very good and I can have a secure platform installed for the batteries. I'm just not sure how to go about venting the bank. And, is there a danger to having them in below the waterline and in a berth in general.

billknny · 16-10-2018, 19:33

Quote:

Originally Posted by Palarran

This situation is a little different as the thick heavy wire right now is running from the stern about 50' forward to my 12v distribution panel. By moving them the lead wire would be about 8'. It's also still about 14' back from the bow. My sterns are very heavy due to extra equipment installed in the aft compartments. This would definitely help with the balance of the boat and also move the weight lower in the hull. Access is very good and I can have a secure platform installed for the batteries. I'm just not sure how to go about venting the bank. And, is there a danger to having them in below the waterline and in a berth in general.

There is a danger, albeit a small one.

I know of three boats with well built battery boxes that were passively vented overboard, that had a loose cable connection spark and explode accumulated hydrogen. Anyone sleeping on top the batteries would have been seriously injured.

Having said that, I do sometimes still sleep on top of my batteries...

Uncle Bob · 16-10-2018, 21:58

Quote:

Originally Posted by Palarran

I'm thinking about relocating my battery bank from the stern of the boat to a spot under floor boards in a forward berth area. Possibly even under the berth itself. I know the batteries gas when charging if lead acid and that would need to be addressed. Is there anything obvious about locating a large house bank in this area?

Hi, the only real issue that I can see is that in the remote offchance that the hull is even partially flooded due to whatever reason then the batteries are all flooded as well leaving no power for bilge pumps, radio etc.

**Jim Cate** · 16-10-2018, 23:52

Hydrogen is very light and has very small molecules, making it kinda hard to seal up and contain. But that is good for ventilation, where you want to get it out of the boat. So, if you can rig a vent line that goes only upward (no loops) and exits on deck somewhere, the forces of nature will generally get rid of the gas. The production rate isn't too great, either, so you don't need a big flow. If you are worried, a small muffin fan forcing the flow could help with the ventilation of the box.

Jim

rom · 17-10-2018, 00:52

Lagoon puts the batteries under the aft port berth (at least on L440 & L450). So more than a thousand boats out there, never heard of any problem. Yes, once a friend of mine woke up at night because of that typical battery smell, it was the starter battery going well above 15V. Starter batteries are under the floor, aft cabins.

FWIW, I have relocated the house battery (1000Ah@12V) in my L440. Put it in the big cockpit locker. Much better balance, better safety, less & shorter cables.

mikedefieslife · 17-10-2018, 04:44

Quote:

Originally Posted by rom

Lagoon puts the batteries under the aft port berth (at least on L440 & L450). So more than a thousand boats out there, never heard of any problem. Yes, once a friend of mine woke up at night because of that typical battery smell, it was the starter battery going well above 15V. Starter batteries are under the floor, aft cabins.

FWIW, I have relocated the house battery (1000Ah@12V) in my L440. Put it in the big cockpit locker. Much better balance, better safety, less & shorter cables.

What type of batteries though?

Emouchet · 17-10-2018, 10:15

My FLA batteries are under my bunk, but I mostly sleep at night.

Since the batteries get charged by solar, they gas out during day time, when port holes are usually open.