Battery Containment - Necessary?

[WStayton]

A battery housing question:

For my envisioned whole-house system I planning to have 24 each US Battery US-1800 6 volt batteries, in three chains of eight batteries each.  I had originally thought to have all of these on their own shelf/table, as near to the generator as possible, to minimize the voltage loss by having a long cable, and directly under on end of the roof solar array, for the same reason.

However, somebody (I forgot who . . .) said that they should be confined in their own containment box because of hydrogen-oxygen from electrolysing the water/electrolyte in the batteries during charging.

What I had originally envisioned was to have them sitting out in a 20' x 30' "room" with all the rest of the pieces/parts for this puzzle.  This "room" has a four foot door on one wall, a three foot door on another wall which is also one of the ingress routes for the living space and, as such, is opened frequently, along with four windows scattered around the perimeter.  The space is currently uninsulated and sheathed with texture 1-11 material.  The space seems to be reasonably tight, but it is far from hermetically sealed. My thought was that the batteries were better off sitting out in this space where the hydrogen, which is much lighter than air (think: Blimp/Deringeble(sp?)) would dissipate without making a bomb (think: Hindenberg), and where I have full and complete access for maintenance/monitoring/checking/testing.  Do I need a hermetically sealed container that is positively vented to the outside to ensure that I won't have a problem, or is the natural dissipation, convection, advection enough to ensure that this won't be a problem?  Any thoughts??

As always, thanx for your inputs!

Regardz,

Wayne Stayton

[mobile_bob]

the problem with hydrogen is its ability to make for an explosive mix over a fairly large ratio of oxygen to hydrogen
iirc as little as 5% hydrogen in the room air and you have a bomb.

depending on battery technology, wet cells offgas profusely compared to agm or gell cells which contain and recombine the vast majority
of the gasses you are concerned with.

you might consider a hooded area with a small pancake fan to evacuate the area over the batteries while they are being charged heavily

you might also consider placing the engine intake air so that it might such up anything too?

i plan on placing my batteries on the back side of the generator room wall, sharing the same wall makes for short cable runs through the wall
the battery room will basically be a subdivision of the larger room such that i can not only keep down the hydrogen issue but also climate control far more economically.

as my plans have morphed a bit since buying the little house in my home town, i am now thinking of using the rear 14 ft of the 40 ft container
to use as the generator and separate battery/control room.  this change is making me study submarine design/engineering to make most effective use of my small space.  at least my space is square with flat sides unlike a submarine so it should be much easier.

bob g

[LowGear]

WOW!

What a brainstorm!  Take the off gassing from the batteries and feed it back into the generator like the geniuses do on automobiles with the electrolysis jugs.

You heard it first here!

Casey

[Lloyd]

Hi All,

FLA's start gassing at about 13.8 volts 70 degrees and reach their max gassing at 14.4 and above. The created hydrogen is explosive at 4% in free air...so the the bigger the bank the more potential, which is increased by by the decreased total air volume the smaller the battery room gets.

So ventilation is very important. A natural convection is desired to a fan ventilation system due to the potential spark hazard of the fan motor.

There are off the shelf battery boxes, made of aluminum or roto-molded plastic which have the inlet exhaust ports.

Batteries also last longer the cooler they run, that is a very important consideration on locating the banks. Keep them away from heat generating equipment, and other sources of heat.

A battery room constructed of concrete or block on the north side of the building is the best local. Well ventilated and then the only need for boxes is to contain any electrolyte spill.

AND FINALLY THE BEST INVESTMENT THAT YOU CAN MAKE TO YOUR BAT BANK BESIDES THE PROPER SIZE WIRE AND CHARGER IS the water Miser vent cap. http://www.flowsystemsusa.com/water-miser-vent-cap.html



I have a 12 year history with these caps...and I won't install a bank with out them. I know they flat work, and every client that balked in the beginning bc of the added costs, has agreed that they flat out, are the best investment they made.

Lloyd

[Tom Reed]

My Hawker batteries came with those caps. After 3 years the battery tops are still nice and clean. They do drink about 1.5 gal of distilled water a month though. Watch it when you snap the caps down though as they do tend to spit out the vent holes in the caps.

[LowGear]

1.5 gallons of water a month?  How many batteries?  Is that normal?  Did you ever run them with standard caps just to get a bench mark?

Casey

[Lloyd]

Did you ever run them with standard caps just to get a bench mark?

Casey

For the doubting thomassss someone else has already been there and done that http://newsgroups.derkeiler.com/Archive/Rec/rec.boats.cruising/2005-07/msg00019.html

From the same thread
Re: Hydrocap - for lead acid batteries

    * From: Spammerdontbother@xxxxxxxxxxxxxx (gs)
    * Date: Wed, 27 Jul 2005 20:31:54 GMT

>On Wed, 27 Jul 2005 11:53:07 -0400, Doin it right <none@xxxxxxxxxxx> wrote:

>Maynard G. Krebbs wrote:
>
>> On Tue, 26 Jul 2005 19:29:28 -0400, Larry <noone@xxxxxxxx> wrote:
>>
>>>Someone corrected me a while back. They said that PT Barnum never said,
>>>"There's one born every minute."
>>
>>
>> I believe it was a friend of PT Barnum's who told him one day, "PT, if
>> there were a sucker born every minute, you'd find a way to take his
>> money."
>> Mark E. Williams
>
>Hate to break the bad news, but the technology used in these hydrocaps
>DOES work and is based on sound engineering principles.
>
>They are kind of spendy though.

some people are just too cynical :-)

Hydrocaps were also used in the manned submersible arena for a long
long time and were mentioned in Frank Busby's Manned Submersibles
book (pg 325) which was published in '76 ... so they've been around
for quite some time.

- Ed

[mike90045]

Hey, two types of caps here:

1) water miser - the yellow flip top, that contains and returns the microspray from the bubbling battery.  I have them, much easier than unscrewing the caps, and trying to place them while checking water.

2)  hydro caps - $$  have a catalyst that re-combines the O & H gas from the bubbles.  Must be removed before battery equalization, as the amount of gas generated creates too much internal heat and ruins the caps.   They have a 5 year lifetime, eventually, the catalyst stops working.


For me, the water miser have kept the tops of the batteries cleaner, by trapping all the mist, and saves where to put the cap when filling.  I don't think they save a lot of water, I still average just over a gallon a month with 8, L16 batteries.

I've also heard the hydro caps are hard to find in stock anywhere.

[Tom Reed]

Yes the Hydro caps contain a platinum catalyst hence the BIG$ for them. Didn't know about the 5 year life expectancy thought.

[WStayton]

Couple of thought and a couple of questions:

1) I was thinking that if I had the batteries exposed and accessable from both sides, monitoring and servicing would be MUCH easier that if they were in a cramped boc and I had to basically crawl in through an access hole to get to the batteries.

2) I was thinking that I would have to water them weekly or, if they were equipped with hydrocaps, at least look in/at them weekly, even if water wasn't required that frequently.  Though hydrocaps are supposed to eliminate/vastly-reduce watering, if they fail after a few years, I can see some of them not being up to spec and failing after six months or a year, and the big dummy, having planned on them being good for six years, could fry/kill some of the batteries due to low electrolyte.  If I am using three strings of batteries in parallell, as planned, having a battery failure in one string is going to transfer stress to the other two string and, maybe, cause them to fail early sooner. Long and short, like my dad used to say, don't trust anybody but your mother, so I would be monitoring them once a week anyway, and crawling through the entrance hatch to a battery box anyway, so, from my view point, I might as well save the $25.50 per battery!

3) About a "hood" for hydrogen collection:  If I built what would effectively be a hipped roof structure and then hung it from cables/pulleys such that I could lower it over/onto the batteries when I wasn't actively  servicing/inspecting the batteries and provided some form of airflow into the bottom of the "hood" and out of the top - would this be sufficient to alleviate the explosion risk???
Using a piece of stainless flexible exhaust tubing to conduct the air to the engine intake, would be pretty easy, and would cover the outgassing during charging, and pretty foolproof:  charging=>engine running=>air flow through hood   However, I THINK that the batteries would still outgas some during during solar panel charging, so I would have to have some form of air flow inducement during solar charging, also.  Would another couple of pieces of stainless exhaust tubing, of maybe 3" diameter,  run up to a vent through the ceiling/roof provide enough flow to eliminate the risk of explosion, or would they need some form of "forced" convection/ventilation to be safe?  I assume that during charging the batteries will warm up, at least slightly, so I would have some natural convection from that, no?

 If I need additional air flow, beyond natural convection, I'm kind of at a loss of how to do it without having a sparking electric motor in the airflow and thus create ANOTHER explosion risk  I guess I could fabricate some sort of remote drive using pulleys and belts, such that the motor wouldn't be in the exhaust stream, but that looks like ANOTHER $500 fix for a $5 problem!  <grin>  Any ideas, guys?

4) About the cost of the hydrocaps:  I have a hard time justifying adding $25.50 to a $47.00 battery from Sam's Club - especially since I think that I SHOULD look into them every week, anyway, just as a matter of good operating practice.  At $25.50 per battery times twenty-four batteries, I see $600 +, growing wings and flying away, without really doing anything for me!  And, I think that they don't COMPLETELY eliminate outgassing, so I would STILL need some sort of vapor/gas collection "hood" to ensure that I don't have an explosion, yes?

Response are solicited, please!

Thanks for reading/commenting, guys!

Regardz,

Wayne Stayton

[mobile_bob]

i am thinking that a hood much like that used on a kitchen range could be fabricated from wire mesh, covered in fiberglass matt and resin would result in a very light structure that could be raised quite easily.  attaching a drier vent hose on top and mounting a small 4" pancake puter style fan
could work adequately to evacuate any hydrogen. those little fans draw very little power and only need to be running when the batteries are charging and maybe when they are under a heavy discharge (that could be an intermittent operation set on a timer for good measure)

you could also make the armature/skeleton of the hood out of 1/4 wire welded to shape, cover it with cloth (i can't remember which one, but it shrinks tightly with a heat gun and  a water spray) and then layout fiberglass woven matt with resin over it all, makes for a really lightweight and
strong assembly.

bob g

[rcavictim]

Cheap wooden strapping to make a very lightweight space frame.  Use screws and glue.  Staple gun, 10 mil poly vapor barrier sheet plastic.  Voila.  If it starts to levitate above the support of the suspension ropes you know you have a hydrogen problem!

[mike90045]

Till you fill a room with batteries, weatherstrip the doors & windows, caulk and paint the walls and ceilings, I doubt you will have much of a hydrogen collection. wood framed with tarpaper and wood siding, roof sheeting, is pretty leaky at the seams, and I doubt you get much buildup in an outbuilding.   One instance where weatherstrip does not pay. 

Now a finished basement in a house, with a brushed vacuum cleaner upstairs....... Roof removal !

[mbryner]

You're making this too complicated.  Just build a plywood box, 4 x 4 or 4 x 8' x 2-3 ft high.   Vent hole on side near bottom, and another vent hole on side near the top.  PVC pipe out top vent thru wall to outside.  Cheap, easy, and very safe.   To check the water all you do lift off the lid.  or even make the lid hinged.

Most of us here on this site have to admit to leaving tools laying around more often than not.  You don't want to accidentally lay down a wrench across a couple of terminals in an open string of batteries.  That would be worse than the H2 bang you're talking about.

Marcus

[LowGear]

Geezzz,

I think my feelings are hurt.  I come up with this incredible idea about venting the batteries to the intake on the engine and no one gives me an "atta-boy".  You're not going to tell me the hydrogen generators for automobiles are bogus are you?

Are there sparks from a brush-less motor?

Casey