battery location - safety aspects

[mike uk]

I know this subject has been discussed before especially as regards weight distribution but I am interested in any views on the subject of battery gasses ie corrosive gasses affecting electronic components or build up of explosive gasses in bilges.

My Mac 26X is a later model (steps down companionway). The starter battery is located in the steering console strapped to the deck. Its a tight squeeze but it just fits. I dont know if this is standard from the factory or if the UK supplier put it there or maybe the previous owner. There are also two house batteries in plastic battery boxes at the very back of the aft berth, again strapped down.

My concern about the starter battery is that there are a couple of electronic devices mounted inside the console and the instruction books for these devices warn against damage from corrosive battery gasses. Its also quite hard to check electrolyte levels where it is. So I was thinking of moving the starter battery and putting it under the port quarter seat. There are two holes fairly high up on the side of this compartment. Are these vent holes? If so, they vent into the main saloon and presumably into the bilges (if battery gasses are heavier than air). So I wonder if the compartment would need some motorised ventilation? I am thinking here about the explosive nature of the gasses if allowed to build up.

Also, what about the house batteries. Its quite easy to check electrolyte levels in the house batteries where they are, and from a weight point of view I presume it is better to be too far back than too far forward. But are they emitting possibly explosive gasses into the boat and ultimately into the bilges??

In short, the question is where is the best place to put the batteries and do they need additional venting? Any views would be much appreciated.

[Pouw Geuzebroek]

Mike, I have a 1999X and it was fitted with one battery inside the steering pedestal only. I have added a second battery in a battery box, on the starboard side Aft, just between the end of the bed and the back end board. That is now my starter battery and the one inside the pedestal is the house battery. Both are so called 'no maintenance' batteries which you can not fill, these have standard a gas valve fitted, so when over charging the gasses are released, preventing an explosion. I think (but I am not an expert) the gas problem only occurs when overcharging. So I should not worry to much about that.

[Duane Dunn, Allegro]

Neither of those locations are the normal US factory location. It sounds like either the export company or the local dealer is doing their own installs. Perhaps there are European regulations that preclude the normal US location. The US factory location is under the small seat just aft of the galley. They provide a metal strap that holds a single group 24 battery in place attached to the seat sitting on the port ballast tank tube.

Even in the US the factory does not supply the battery, it is a dealer installed item.

This single battery handles all the electrical needs for the motor and the house.

I added a second battery to my system simply connected in parallel.

In this picture you see mostly the added battery which sits strapped to a plywood base that is also under the battery strapped in the factory location. The one in the factory location is at the bottom tucked mostly under the fiberglass. This does make it hard to check the level in the battery in the orginal location. A battery box would be better, mainly to contain any spills. I added the insulating caps to protect against any accidental shorting problems. The shunt for my amp hour meter and my negative buss bar are on the plywood next to the battery. My wiring is still a combination of new marine grade wire and the original non-marine white lamp cord that the factory uses.

[TonyHouk]

Hey All,
I think European regulations require the batteries to be installed outside of the cabin. I read that somewhere but I can not remember where though. I hope that helps and happy sails, Tony

[Duane Dunn, Allegro]

I don't think that can be it as they each have batteries in boxes at the far end of the aft berth inside the cabin. This particularly wouldn't make sense for normal sail boats which usually have the batteries down low in the bilge spaces.

Maybe there are some wierd distance limitations on the wire runs that force the batteries to be installed farther aft.

[norbert]

as reported before: starter battery starboard aft at the transom (inside! ) at the nearest position to the engine. house battery under the cooler liner next to the cb housing in the cener of gravity. if i ever will add a 3rd one it will be on the same spot.

i have a 100 litres (~25 gallons) water tank in the bow under the v berth for better weight distribution. if you do not have additional ballast in the bow this may be the place to install your house battery.

[Robert M. DeVore]

Mike, I believe battery gases are not heavier than air and will not seek the
bilges. One should attempt good ventilation and avoid placing electronics close to the battery because battery gases increase corrosion.

[kmclemore]

Mike, I believe battery gases are not heavier than air and will not seek the bilges. One should attempt good ventilation and avoid placing electronics close to the battery because battery gases increase corrosion.

Most lead-acid batteries ('wet cells') outgas pure hydrogen, which is considerably lighter than air and will easily drift up and out any opening. However, it is also violently flamable when kept contained and allowed to become concentrated (I believe I told my battery explosion story somewhere else on this forum, so I won't repeat it here).

And it is also true that these types of batteries emit a 'mist' of acid which can condense on nearby cool items (like metal brackets, etc.) and will damage them. It is particularly bad when the battery has been charging for quite some time and has become quite warm, whilst the surrounding air is cool.

As for me, I like keeping battries about as well ventilated as I can... but then I lost my eyebrows and skin to one once, so I guess I'm just kinda cautious (fortunately both grew back).

[Moe]

My dual batteries are mounted on plywood in the same location as Duane's. I don't like that much weight being so far from the centerline.

While I could balance it with an equal weight of water under the cooler on the other side, in the event of being swamped, the water weight essentially goes to zero (as does the water ballast) and the battery weight stays the same.

So I've put two small fenders under the plywood, and a larger one between the outboard battery and the hull, to provide at least some extra floatation there. I'd like to get even one more in there.

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Moe

[Duane Dunn, Allegro]

I find my battery weight to port is pretty much offset by the cooler weight to starboard along with the pantry weight (forward dinette seat locker). I'm still amazed that with all the stuff in and on my boat it still sits right on it's line front to back and aide to side. I was sure when I went to 27 gallons of gas in the cockpit it would be butt heavy particlarly with a 60lb extra outboard hanging off the transom. Still sits right in line with the boot stripe.

[Moe]

I've considered that the weight of ice and food in the cooler will help offset the batteries, in normal operation. But in a swamped situation, that ice, and much of the food, is positively bouyant.

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Moe