Battery ventilation on 26x

[tp56ihs]

Just wondering about battery ventilation. My 1996 26x has 2 batteries under the seat aft of the sink. If I charge these lead acid deep cycle batteries in the boat there will be some hydrogen gas generated. Do you think that the cabin ventilation is good enough or should I somehow vent or move batteries ?

[kmclemore]

Unless you've somehow hermetically sealed the access ports to the bilge, I doubt you'll have a problem. Hydrogen gas is very light and will escape quite easily using the first crack it finds.... similarly, it will also escape your cabin through the hatch. I've never heard of a battery explosion on a Mac. That being said, the usual precautions should be observed when charging - disconnect the charger from the mains BEFORE you disconnect it from the battery to avoid sparks (right near the source of the hydrogen gas).

[Tomfoolery]

That space is open at both ends (under the galley and into the stern 'bilge'), allowing for a lot of diffusion and dispersion. Those spaces are far from air tight. I don't worry about it, but you could always add a louvered vent to the cabin in the vertical surface that makes the front of the seat pedestal, if you want more air flow through that area.

[mastreb]

Hydrogen won't build up in a Mac. It's very aggressive about moving up and actually only collects in sealed dome-like areas. There's nothing like that on a Mac that's rightside up. No need to worry about battery ventilation on these boats.

[Chinook]

One thing you might want to pay attention to involves the installation of electronic components. It's sometimes tempting to install small things inside the battery box. When I was installing controllers for my 2 solar panels, I noticed that the instructions advised against installing them too close to the batteries. I'm not sure, but I suspect the manufacturer felt there was possible hazard spark. I installed mine on the outside face of the battery box, in the aft berth airspace.

[seahouse]

Under some situations batteries (mostly flooded lead-acid, but others do at times as well) emit toxic acid vapours, or it can splash when being checked, handled or filled. Pull a cap off a discharged battery being heavily charged and hold a flashlight up to the electrolyte if you want to see a visual demonstration of the vapours being generated.

Also witness the corrosion that happens at the terminals - it's mostly from the close proximity to the acid fumes and vapour coming from the battery. I would not want any sensitive electronics, or anything sensitive to corrosion anywhere near that environment, particularly in a confined area. Newer flooded lead-acid batteries have a porous recombinant matrix inside the caps that helps this but does not eliminate it. The matrix also somewhat "explosion-proofs" (like a flame arrestor) the battery itself from flammable gasses (from an ignition source outside the battery case) as well. It's one reason to not remove the caps from a battery when recharging it, like they did in the old days before the caps were made this way.

-Brian.

[Highlander]

Well I installed a bilge blower for various reasons & purposes of ventilation
http://i844.photobucket.com/albums/ab1/ ... 010053.jpg

I have two of these adjustable vents one in the head the other in the V Berth
http://i844.photobucket.com/albums/ab1/ ... 0009-1.jpg

http://i844.photobucket.com/albums/ab1/ ... 010021.jpg

http://i844.photobucket.com/albums/ab1/ ... 010005.jpg

I also installed grill vents in the front of the rear S/B dinette seat & on passage side of the same seat where the ladder is as my battery charger is there & creates a lot of heat in there this also gives lots of ventallation for the batts

J

[tp56ihs]

Thanks All. Good info I feel better now. Thin I will keep any electronics out of the battery area.

[bobbob]

Would this be a concern with AGM batteries?

[seahouse]

AGM's vent too, but very rarely, and under unusual circumstances. There is a valve that opens to release gas when it exceeds a certain pressure. Below that (which is normally) and it's a recombinant effect; the gasses get "recycled" back into the chemical process.