Fitting Battery Boxes

[SteveMac3]

Bit basic I know but how do you fit them?
Straps inside screwed down through the box to something solid thereby breaching the acid tight integrity of the box OR
Straps outside holding down box and battery but having the potential for a battery sliding about a bit in the box?

One commercial website I came across referred to using penny washers and self tappers to screw the box down and in the same breath mentioned that the box was impervious to petrol and acid. I know I'm dense but why would you want to store petrol in a battery box especially if you drilled holes in the bottom?

 

[gjeffery]

I strap down the box, containing the battery. I pack the battery inside the box, using cut sheets of 10mm closed cell foam taken from an old camping mat (kip mat).

The packing is non absorbent, and prevents undue distortion of the battery box. I also fit 25mm square fiddle rails around the battery box, to stop the battery box sliding, and to aid the straps.

 

[Guest]

If you check out Caravan shops etc. - you will find purpose designed battery box's for fitting.
Many have the strap oustide the box. It is simple matter to use high density foam blocks to 'wedge' the battery in place.

Many boats such as mine have 'DIY' box's made of ply - some glassed up internally to seal and stregthen, many actually just painted.

Penny washers and self-tappers are fine ..... many box's are designed for this in the bottom - to be screwed to timber bearers underneath. My box's albeit DIY job is actually a section of the under-bunk divided off and painted to be acid resistant.
As to petroil resistant .... this is a provision for when battery's are sometimes fitted into engine bays etc. and has nothing to do with petrol INSIDE the box.

At the end of the day .... the box is screwed to an immovable part of the boat or bearer .... straps to hold lid on and battery wedged - or strap holding battery in place, lid clipped over.

Just a final note ..... a lot of people advise against siting batterys inside cabins such as mine .... a common finding on older boats .... many advise a battery box in a cockpit or transom locker to stop vented gases collecting in the cabin .... from charging. This is a valid point - but as long as you have ventilation clearing the cabin in reasonable manner - it should not be too big a problem. The only time this could increase to significance usually if the batterys are overcharged and start gassing off .... then you get that sulphurous smell that irratates the nose .... be careful then as possible flammable hydrogen etc. may be present .... open all hatches, battery box, stop charging etc. Sounds bad - but in fact is not common and as long as all is in reasonable condition .... should not occur.

Another area where common sense and logic plays its part.

 

[Shantyman]

Nigel said . ...... be careful then as possible flammable hydrogen etc. may be present

For Flammable read EXPLOSIVE and then think again.

I would always work on the principle of sod's law of the sea, i.e. what can't happen probably will, and at just the wrong moment. For my money a battery box should be gas tight and properly vented to outside air.

Regards,

Shantyman.

 

[boatmike]

Agreed. And "vented to outside air" should mean from the TOP of the box, (hydrogen being lighter than air) to the cockpit, or some other convenient space and not to the cabin...... I have seen many battery compartments in lockers vented at the bottom. This is correct for a gas compartment (butane or methane), but wrong for hydrogen.

 

[LORDNELSON]

My batteries all sit inside a sheet of 12mm ply which has three cutouts to hold the batteries from sliding laterally inside a vented locker. They are tied down by straps attached to the ply and taken over the top of the batteries. In my case no separate battery boxes are used because the locker is a dedicated battery locker but the same system would work with batteries in individual boxes.

 

[ashanta]

I think Nigel was saying that some boats (like mine) are unfortunately designed with the battery box inside the cabin. It would be very difficult if not impossible to relocate the batteries to the cockpit on my boat. Therefore, I take all the precautions I can under the circumstances to reduce the risks to the minimum.

Regards.

Peter.

 

[kingfisher]

Hydrogen gas is completely different from propane or fuel damps.

Hydrogen is much lighter than air, so will escape immidiately from the boat.
You can keep fuel fumes and propane in a jar, without a lid. You can't do that with hyrdogen.

Also, hydrogen being a smaller molecule than carbon based fuels, can escape trough even the tiniest crack.

So even if the battery pack vents into the cockpit, it will be impossible to generate the necessary air/gas mixture with hydrogen to cause a dangerous situation.

But please don't smoke while looking directly into the box.

 

[Guest]

Older boats ...

It is common on older boats to have battery's in under-bunk situations .... the accidents that occur with this ? I haven't actually heard of any except where some twit stows an unsuitable object there .... !!
The amount of gas produced should only be a small amount and not normally a problem .... my locker would clear any hydrogen gas produced quite easily as its not sealed down for that reason. If the battery(s) are producing a lot of gas .... then there is something wrong with the system / charging .... as the battery(s) are then being 'cooked'.
I have looked at siting it in a cockpit locker ......... but at the end of the day - like most older boats the cockpit lockers actually are not sealed off completely from the cabin anyway ... the only one on mine that is - is the Calor Gas locker ..... which vents o/board etc. The only way I could move the battery's to an outside locker would be to cut the aft part of the stbd cockpit bench and set a locker for them .... basically a battery box 'hung' from under the bench etc. with the cut bench section then hinged as a lid etc. ........ on second thoughts - the boats survived 30 odd yrs like it - it can stay as it is till battery's are no longer the hunking great blocks as now !!!
/forums/images/graemlins/crazy.gif

I am very interested to hear about actual accidents having occurred with battery(s) having been sited inside .... it's not that I don't believe ... it's that I want to know what happened !!

 

[tugboat]

>For my money a battery box should be gas tight and properly vented to outside air.<
If the box is airtight with a vent pipe all that will do is prevent any buildup of pressure in the event of gassing. The gas will not escape as there is no circulation and therefore no ingress of air to let the gas out. Thus the gas is locked in with a couple of possible spark generators. In the world of compromise which is boating, my own preference is for the batteries to be allowed to breathe freely with good ventilation all round, and try (through maintenance) to avoid any sources of ignition. All IMHO of course. PS Tugs rule OK. /forums/images/graemlins/laugh.gif

 

[silverseal]

I found a double battery box in a local supermarket, as I needed to have a box for 2 x 110amp service batteries. It cost about £5 complete with lid, held on with bungy cord and is sold as a small plastic storage box.
It has a nice large outer lip at the base, so a number of screws can be inserted into the plywood below, without affecting the integrity of the box itself, so it remains acid tight.... rather better than most "proper" battery boxes which I have seen.
I'm off now for an extended cruise courtesy of P&O, round a small island south of Hampshire - shame I paid £40 grand for it

 

[SteveMac3]

Thanks guys, my installation will be under a bunk as existing. It is vented but I shall add some battery boxes and put the straps under the boxes and over the top. The batteries will be wedged in the boxes with an old camping mat that I have.. And I will use the idea of some cleats to stop the box sliding about.

 

[William_H]

Most safety standards for battery charging facilities require a room with fireproof door and positive ventilation to outside. This for charging about 12 batteries at a time and may be a typical beaurocratic overkill. Obviously most boats have bateries in the cabin and you don't see fires from batteries like you do from petrol or gas leaks. I certainly think that if I had a large battery bank especially when using a smart charger I would fit a small computer type 12 volt fan to ventilate when charging. This I uderstand is a requirement for electric cars with lead acid batteries. As for the battery box it needs to be able to contain the battery when inverted and you need to make sure there are no screw heads into the box which could wear a hole in the plastic case of the battery. regards will

 

[Guest]

\"inverted\"

If my boat ever went inverted - I'm gone !!!

I would consider that any box / locker or whatever that has a lid - would have to be really good to a) survive the weight of average boat batterys inverted on its lid, b) to keep the acid / fluid completely inside the box...... given that to have such a situation would often be a violent action and not as you read in novels .... the slow roll !!

Given that the box is vented ....... that means whatever direction the acid / gas was going in prior to inversion is now 180 degrees out .............

As to separate room with firedoor and ventilation - yep my 25ft motor-sailer has plenty of room for this ....

/forums/images/graemlins/cool.gif

 

[snowleopard]

my domestic batteries are prevented from sliding around in their locker by a liberal application of DIY shop aerosol foam. there is also a wooden bar across the top of the locker to stop them falling out if inverted.

boxes for the engine start batteries are strapped down to shelves with dollops of sikaflex underneath to stop them sliding. the batteries are held in the boxes with more spray foam.

when a battery needs changing it is the work of a few minutes to chisel out the foam.

 

[fireball]

Turn the jar upside down to store hydrogen!

 

[Guest]

You can try this in lab ....

A gas suffers a difusion over time irrespective of its relative density .... with the surrounding gases except where so dismilar that they cannot mix.
The scenario of inverted jar will hold for a period - but eventually the gas will difuse and disperse to atmosphere exterior if any small leak etc. Same with jar right way up with heavy gas .......

fact not fiction.

Hydrogen is a gas that disperses rapidly as it is completely acceptable to atmosphere ..... and the amount produced by a charging battery is not so great.... unless seriously at fault.