powerhouse design

[random]

Hi folks.  A couple weeks ago, a cougar (or equivalent) put its pointy little claws through two of my plastic gas cans, which I've been leaving outside next to the van.  Currently I only have physical space for the 4 pseudo-deep-cycle batteries that are now under the floorboards of my van.  It is clear that the next thing I need to do is build a powerhouse.

Concrete is relatively cheap (about $3 for a 50-pound bag) and gravel is plentiful (the whole place is sitting on decomposed granite) so I'm going to try casting my own bricks in 1-gallon plastic water bottles.  If that doesn't work I'll probably go to cinder-blocks.

In any case, my next project is to construct a powerhouse.  There are some conflicts inherent in this little project.

1.  Hydrogen emission during charging.  The area where my batteries are currently stored is well ventillated, but we're talking a new storage area here, and I certainly don't want to build myself a bomb.
   
2.  Freezing.  It gets down to around -15F in the winter.  No good freezing your battery bank.  When I set up the van I never really considered freezing, but apparently I've been lucky.  That, and the battery bank has usually had a pretty decent charge on it since I've been using power primarily from my generator.
   
3.  Ventillation.  I need to build this powerhouse in a way that lets me run the generator inside.  Current measures are different from what was in use in the past, and are stopgap.  If I have to work on the generator (which needs to be done once in a while) I don't want to be doing it in the snow.
   
4.  Gasoline storage.  Gotta get the plastic cans out of kitty's reach.
   
5.  The freakin' bees.  In the summertime, any hole into a building on the east or southeast side is an openv invitation to the local bees to build a nest there.  Two years ago the little buzzers made a nest behind the refrigerator in our trailer and it was a real mess to deal with.
   
   

So there are some interesting conflicts here.  I need to keep the battery bank area well ventillated but as warm as possible.  I need to keep the bees out (1/8" hardware cloth should take care of that one).  I need enough ventillation to run the generator inside without poisoning myself on CO when I have to go inside to do whatever (as in add fuel, I customarily add fuel while it's running if it runs low).  I need to keep the gasoline separated from the rest.

Last summer I think it was, we dug out a place for the powerhouse, in the side of a hill.  That side of it can be about 8 feet.  That side is also closest to the road, so if we ever hook up to the grid I'll want to bring the gridline in to the powerhouse as a distribution point.  

I'm thinking the best place for the battery bank is up against the hill on that side so the earth can provide some insulation.  Probably on the south side of that area.

Not sure quite how much space to leave for the battery bank.  I run a workshop so I'll want to leave plenty of space to expand the battery bank later as batteries become available at the right price.  I'm thinking store the batteries on several stacked pull-out drawerlike thingys for easy access when servicing them.  

I should probably have a solid wall between the batteries and the generator, and another solid wall to keep the gasoline stash separated.  The whole thing seems like a lot of work.

What have I overlooked here?  Has anybody done something similar?  What did you do wrong or right?

[Volvo farmer]

I recently went through this. My design seems to work pretty well so far, though we've only been out here less than a month.

If money is an issue, I think it is much cheaper to build with conventional materials. I had almost enough stuff left over from building my house to build this whole shed. A carpenter buddy of mine put the whole thing together in less than a week. It houses my batteries, inverter, charge controller and generator. It's 8'x 16' (maybe 20'?) and is big enough for everything with room to spare

 

Keep in mind a couple of things. Code requires something like 30" in front of your batteries and in front of your  equipment for servicing. I was advised to build a partial wall, put the service equipment on one side and the batteries on the other. It turned out well. This is taken from standing just inside the doorway

For batteries, I was advised that they will self-heat themselves somewhat with charging and discharging. I built a plywood box, lined it with 2" foam and pond liner material, and put a sloped lid on it with a vent at the high side for hydrogen. This sits directly on the other side of the wall from the power panel, keeping the runs of heavy gauge wire as short as possible. I don't know how well this will work in the winter but it seemed the best solution to keep them warm.

Since my batteries are in a box, I just put the generator in the same room. I don't know if I'd store gasoline in there or not, my generator is LP. Maybe build a very small 3'x3' box outside the shed for gas?

The one thing I had to give up with this design was DC in the house, the run was just too far and the wire would have had to be too large to run any sort of DC load.

Hope this helps

[nanotech]

As for the filling of the petrol, I'd take a design hint from the automotive manufacturers.  They generally put the fuel tank as far from the engine as possible, and use a remote filling tube to the tank.

Is there any way of doing this in your situation?  Maybe go to the wrecking yard and grab the rubber filler tube from a Chevy pickup ('81 has dual tanks on the Camper Special which have REALLY long rubber filler tubes).  That way you could have a closeable, designed-for-gasoline, remote filler for the fuel.

Most also have the vapor line for the release of vapors from the tank.  Would be handy to be able to hook that up so you don't have to worry about vapors in with the running engine.

Heh, and as for the bees, you could always have a diverter valve on the generator's exhaust so that when you're not required to be in there, it fills the hut with exhaust, then when you need to go out there, switch the exhaust to outside and ventilate the hut!!  No worry about bees in there then!!

(the above paragraph is totally in jest.  In no way would I ever recommend doing it for real!!!)

[DanG]

Three words: EYE WASH STATION. However you can manage one, 3 or 4 gallons of water mounted on wall just away from battery area with an easy to use gravity fed valve and wash wand on hose to flush eyes, face, hands etc. ASAP in case of mishap. Some neat simple commerical units are available and require annual flushing plus they had their own preservative pack for the water - for a DIY'r I might ask a pharmacist what to use.

On battery room venting: Hydrogen is about 30 times lighter than N2 and O2 so it screams upward, rising faster than bubbles in water. When hydrogen is produced it's in a constant outgassing that you NEVER want to allow to build up against the ceiling - a small amount of draw (or smokestack effect in non-living area airspace) vented off at the highest point (not near the highest point, THE highest point) in battery room is all that is needed.

That's how the power division did it at my old workplace for a basement 32' x 8' Edison cell bank using "not-enough-draft to blow out a candle" from a 2"x10" vent exhaust but 24/7/365 ON with sail-switch alarmed, low rpm, explosion-proof squirrel cage fan. It goes w/o saying there should be no source of spark or heat on or near the ceiling, the fan motor is to be mounted outdoors or in seperate protected airspace, and explosion proof enclosed lighting fixtures were used only on walls.

The batteries will give off real acid vapor (not just odor events) at times, first rising up from heat then cooling and drizzling down to corrode metal, lungs, hair, clothing, etc. The steady bleed of positive pressure venting or draw-off will catch alot of that during unattended operation, but designing in cross ventilation with doors, or door and window, or door and roof hatch on opposite sides of longest dimension of room makes it nicer to work around when attending to service or repair duties.

And for the slab floor - Hosing or rinsing off the battery cases and floor as needed should be do-able. Allow for a floor drain even if only to dry sump or pipe run just to outdoor edge of slab; meerly planning to allow the rinse water drainage to exit through entry door is not wise since someday you may meet a stream of acid exiting while you are trying to enter.

~

[Don Cackleberrycreations]

You might consider an outside fuel tank  say a 15-30 gallon drum and run a fuel line to the generator. This would keep fuel vapor out side the shed greatly reducing the chance of explosion should a spark occure (trust me second degree burns are no fun as I discovered the 4th after an accident during the set up of a professional fireworks display)

The exaust can also be routed to the outside  though personally I would have the generator in its own small enclosure  and run the powerline into the shed .

The batteries should be well vented as well Hydrogen gas poses a real danger in an enclosed space.

[Bruce S]

To this one I would add. Keep a box of good ole baking soda near. It's the one thing that with water will nuetralize battery acid and those nasty burns that comes with getting it on the skin.

It is one of the items commonly found in eye wash fluids. 1 Tablespoon per quart is the eye wash station ( as I look at the unit in our battery testing area).

Hope this helps

Bruce S

[random]

It looks like the hole in your battery box is about 1-1/2" diameter, and it looks like there's a bit of space between it and the absolute top of the box.  I'd be concerned, about two things.  First, a single hole makes it harder to ventillate the box, two holes on either end would allow some minor air currents to help with the ventillation.  Second, I'd want a hole about 6" in diameter minimum.  So basically instead of one hole 1-1/2" in diameter in the middle near the top, I'd want 2 holes 6" in diameter at opposite ends and at the top of the box.  Maybe it's no big deal, but I've seen pictures of the Hindenburg disaster and I don't want to go there... paranoia can pay off.

[random]

"Three words: EYE WASH STATION."

Good thought.  Now, the temperature outside the powerhouse will be (worstcase) -20F so how do I keep the water in the eyewash station in liquid form?

If I'm going to be popping the tops on the batteries, I'll have a 1-gallon jug of distilled water in hand.  It will come from in the trailer and it will not be frozen.  I'm gonna stick with that unless I can be sure my eyewash station won't be full of ice.

I appreciate the suggestion, but some folks live in warmer climates... I lived in California for many years and the concept of water freezing outside was one that just about didn't even come up.  Where I live, it's a definite concern.

It's kind of scarey to think about what conditions in Antarctica would be like.

[Volvo farmer]

Hi Random,

I believe the actual pipe is 2.5", though the fitting on the end is slightly smaller than that.  There's also two smaller vents near the bottom of the box, in the opposite end. I had a local guy with some solar install experience vent the box and this was his design. I'm not real worried about it. I've just never heard of very many real world examples of people blowing up their power sheds because of hydrogen gassing. Cross ventilated with 6" holes would perhaps be safer, but would also let a lot of cold air in in the winter, which I'm not too keen on doing.

[elvin1949]

Random

 Bruce s gave you all you need to know to set up a good "eye-wash-station". Please do.

Not having one almost cost me my sight.

A battery blowing up in your face is not something i want to go through again.BUT if it happens i am now prepared.hope i never need it.

Be careful and have fun

later

elvin

[Bruce S]

Random;

   Since you're going to have the batteries in the "shed" keep the eye-wash station in there.

The closer to the working area the better. Shouldn't be too hard to make use of a plastic milk jug. Put a hole in the bottom that will accept a neoprene or rubber hose, hot glue the hose in place. Using a hook and string, fill the jug with neutralizing solution and hang above work area. I pretty sure that with it in the shed, it won't get to the freeze point since even the batteries during usage and outgassing during charge will put out enough heat to keep things above the freeze point.

Lived in Lakeshore,MI back in '73 and it got COLD there, we did this and did not have a freezing problem.

The power shed was more for the barn than anything else, and we used the car & tractor batteries to run heaters for the horses and chickens, but it always seemed to be nice and toasty in there.

I've been up in the Klondike's during a winter, can't and really don't have any further desire to get any colder than that.

Antarctica IS NOT a continent I want to visit :--)

Hope this helps

Cheers

Bruce S

[random]

"I pretty sure that with it in the shed, it won't get to the freeze point since even the batteries during usage and outgassing during charge will put out enough heat to keep things above the freeze point."

I'm skeptical about the freezing issue, but it won't cost much to find out for sure.  Thanks guys.