Lead Acid battery Installation

[shewitt]

I am looking to move my batteries to the floor void just above the keel which is not ventilated. I have seen some lead acid batteries with plugs and plastic pipes connected to disperse any gas away to a vent. Has anyone come across this type of set up and where can I get them? Any advice on installing lead acid batteries in a none ventilated compartment would be appreciated.

Thanks in advance

Wayne & Sue


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[halcyon]

One point to concider is that the void above the keel is the first to flood from any water leak. This means that you are likley to flood them and loose battery power, and anything connected to it.

Brian

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[MainlySteam]

This is something I would be interested in others views on too as the importance of ventilation seems a little over emphasized for the typical small boat installation.

Hydrogen is of low molecular weight (the lightest of anything) so will sqeeze through any microscopic crevice - it is also much lighter than air so rises rapidly. This means that if the batteries are to be put in a covered and vented box, then the lid has to be designed to trap the gas and vent it from the lid. Usually this is not how it is done and so the results are of no effect (large installations will use fans though).

In my own boat the compartment holding the batteries is vented to the outside of the boat but from the side of the box and just below the overlapping lip of the lid which means, in fact, that the gas goes out of the crevice between the lid and down under the lip overlapping the side of the box into the cabin once the lid fills with gas - the lid actually creates a trap for some gas (like an inverted glass plunged into water).

This has never worried me as I have never heard of a hydrogen gas explosion on a boat which occurred spontaneously rather than when the batteries were being worked on (no doubt it has happened but must be very rare). Once the gas escapes (which as pointed out above it will do as slickly as a snake) it will rise to the top of the cabin and vent from any cracked hatch, etc and I cannot imagine a normal boatload of batteries creating enough hydrogen to present a hazard in the cabin. Before checking the batteries I always allow a few seconds to elapse for any gas to rise after opening the box (and also do so when opening a cell) - in my view only seconds are needed because of the buoyancy of hydrogen.

So, in my opinion, putting aside the real danger from flooding as mentioned by another, batteries can be safely placed in the bilge from a gas point of view as long as the bilge has some free ventilation upwards (through the sole hatch cracks or up the inside of the hull between it and the linings). They should, of course, be placed in an acid proof box and if placed in a position where metal objects can fall on them they must also be covered.

Note that my comment on venting is contrary to much advice (but not contrary to alot of practice) and should be regarded in that light.

John

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[ongolo]

Hi mainlysteam,

for a change I have to agree with everything you say.


regards ongolo

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[MainlySteam]

/forums/images/icons/smile.gif and /forums/images/icons/smile.gif again

Regards

John

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[William_H]

Hello Wayne and Sue. No one has mentioned the fact that hydrogen is produced when charging. So if you have a high currwent smart charger you have far more concern than if you have a solar panel or wind generator with only occasional engine generator charging. There are some magic little computer type fans available noww which could be fitted into a duct and connected to operate when the engine is running. This may aleviate your fears. It doesn't seem to be a major issue in boat design that I have seen. Light aircraft use a sealing lid and hoses about 1cm id one in and one out into the slipstream they have an angled cut facing into or away from the slipstream. This idea may suit although you would need larger tubing and a means of stopping water ingresas. I note also that electric cars require positive ventilation when being charged. Regards will

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[halcyon]

We bought out dual voltage chargers back in 1983, charging up to 14.2 - 15.2 depending on battery type, before droping to float charge. We used to include a control output to run a fan to extract any gas on the high charge rate. I think only one firm actually used this facility, and I do not know to any boats blowing up from hydrogen gas.
So you are probably not far off.

Brian

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[Phoenix of Hamble]

Wayne and Sue,

I think you should pay particular attention to the comment about flooding getting the batteries wet....

The very time when they get flooded is the very time you'll most need them....

Anyone who has sailed for long enough will have experienced water coming into the bilges through spray/pooping/broken seacocks etc etc...

I would personally be very hesitatant to put batteries in the bilges unless you invest in waterproof enclosures for them at the same, at which point I guess the interesting debate about venting becomes much more relevant..

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[Phoenix of Hamble]

Thinking a bit more about this, I guess we should also ask if you use gas on board at all (butane/propane!) or indeed any other fuel (perhaps with the exception of diesel)... if so, then this is another VERY good reason for not putting batteries in the bilge unless you are VERY diligent about running the pumps before starting up.. and even that action is dangerous if the batteries are in the bilge...

I respect other peoples opinions, but I think its seriously misguided to put batteries in the bilges.. if it made sense then all the big manufacturers would have done it years ago in their relentless pursuit for more accomodation space...

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[MainlySteam]

I suspect that one reason, perhaps the main one, that production manufacturers do not put the batteries in the bilge is because the bilges are so shallow that they will not fit. I have certainly seen batteries in the bilges of well thought out modern custom designed vessels with deeper sections (for collectors of Yachting World there is an excellent example, Troubadour, reviewed in detail in the January 1998 edition).

Also, just as batteries do not spontaneously ignite their own hydrogen, they also do not spontaneously ignite LPG's or other inflammable fuels as it is suggested that they do. If they did we would be having at least hydrogen explosions every day of the week.

John

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[halcyon]

One boat builder fitted them between engines, pipe splits leaking large amounts of water. Of cause the auto bilge pump decides not to work, result flooded engine room and batteries. Resulting in loss of EDC throttles, engines, all nav equip, vhf infact all power. The real downside was that they were also mid channel ( English ), with only flares.

Brian

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[shewitt]

Thank you all for your help. It would appear to me if I can install batteries which can be man handled (110 a/h ?) inside a water tight box with a top exit vent pipe which has a extractor fan for boost charging, piped to the outside. The chargers/ regulators set to charge the batteries without gassing off I should be ok

PS

This installation is only for my service batteries my engine start battery is actually positioned higher then the engine in a separate locker. I could also use the start battery for emergency supplies such as tri color and instruments in the case of flooding

Regards

Wayne & Sue


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