[RE-wrenches] Battery Box Construction

Fri Jan 29 15:20:42 PST 2016

Luke,
I have used a number of coatings over the years. My go to coating is made by 3M, I believe its called Heavy Duty Performance coating. 3M rates it resistant to Sulphuric acid at something like a 15% solution, but I have seen some boxes I made in the early 90s that were pig-sties and the coating looked good. The best most durable coatings I’ve used are Marine bilge and engine paints that are epoxy based. In the jargon of today, bomber. Around $250.00 a gallon. I have a cabinet shop apply the stuff since they have the ventilation set up for dealing with the fumes, and drying racks. I’ve used two “bedliner products” One deteriorated after a few years from normal gassing” The other seams to be fine. Pans are thin gauge stainless. 

Rigidity for the plastic boxes is achieved with angle stock. Angle, and channel are stainless, but I have used aluminum both plain and anodized, and etched and painted and saw a plain one that’s fifteen years old and the aluminum looks ok.

The plastic boxes are light duty in that you wouldn’t set a heavy tool box on top or certainly sit on it. They aren’t flimsy like the commercially made HDPE boxes, which I actually like, and use a lot. I’m sure to let my clients know this, and they are all told that if my electrical room or shed becomes a storage room/shed, they are fired!

The price range for a box that would hold (16) L-16s or that equivalent volume is 1,000-2,500. I have found that a decent basic plywood box that is coated inside and has a tray pushes the bottom end of that scale. I’m a serious woodworker and have a commercial shop and still can’t blow one out for much less.

 I think my boxes hold up well because I make sure that if passive ventilation is used, that it actually is working. I have had to alter intake and exhaust ports, both location and volumes to get air to move. The physics are beyond me. My preference is dual power vents, one being a back up. I like to install indicator lights so that my clients have a heads up if one goes out. Some die prematurely and some live long healthy lives.

On a final note. I DO have a lot of systems out there with plywood boxes. Sometimes the clients insist, and I tell them to make one. I also do a lot of pro bono work for the elderly, vets, and backwoods folks who have fallen in hard times, and there funds are scant.

Michael Morningstar

> On Jan 29, 2016, at 9:08 AM, Shasta Daiku <mjmorningstar at gmail.com> wrote:
> 
> I have always been dismayed with wooden battery boxes used in professionally installed power systems. It seems vey DIYer/HomePoweresque. Where else is wood used in electrical installations? I have on occasion built some BB plywood core boxes, sheetmetal outer skin/ FRP inner skin/ raw edges and corners banded with SS angle/ rubber gaskets with lots of latches.
> 
> I build boxes that are made of either plastic or metal depending on the environment and usage they’ll see. Plastic, that is HDPE or acrylics, I order online cut to size, or from a glass shop. 1/4” thickness. Metal, heavy gauge sheetmetal, I have cut by fabricators, and then coated with non-corrosive/conductive coatings by a cabinet shop.
> 
> Here are some general guidelines
> 
> -With either material, I keep the panels sized small. Less than 2’ x 2’ is nice, both for shipping and handling. 
> 
> -Panels can be attached to each other using H and U channel, and angle stock (which also gives rigidity). Lids are usually sectional rather than a heavy 
>  single lid. Sometimes, on plastic lids I rout rabbets on the connecting seams so that the there is a half lap joint.
> 
> -Plastic can be drilled and tapped. I generally avoid using adhesives because they are toxic as Hell and pieces want to slide out of alignment.
> 
> -When batteries sit on metal racks, I enclose the racks with acrylic sheets using rare earth magnets. Magnets are attached to the acrylic with epoxy or the 
>  magnet will have a counter sunk hole and machine screws can be used.
> 
> -I seldom build a box with a back wall. Instead, I apply a sheet of FRP (fiberglass reinforced plastic) to the wall that the box sits against, smooth side out.
>  Side panels butt against, and are attached to the wall using U channel or angle stock. This accommodates a wall that may not be flat or a 
>  wall/floor intersection that isn’t square. Corners, That is sides to front pieces are made with angle stock. They knock apart by using wing nuts or 
>  magnets. That way the front of the box can be removed for placement/replacement.
> 
> -I stopped using hinges for lids along time ago, when I started making lids that were sectional. Lately I run a length of U channel against the back wall, the 
>  length of the box. The width of the channel is wider than the thickness of the sheet, so that the sheet will slide in easily. The lid section is removed rather 
>  hinged up. You know the saying “Don’t let the lid hit you in the head!"
>  
>  -Over the years I have tried a lot of coatings in my metal boxes. All have held up well, but I have found that engine compartment type undercoatings to be
>   my favorite.
> 
> -If I have a say in the power room/shed design, I will specify a concrete slab with a shallow basin for the batteries to sit in. The basin has a floor drain and is epoxy coated. Otherwise I have a sheetmetal tray fabricated and have it coated. The tray is separate from the enclosure.
> 
> 
> -In very hard use applications I have the box made by a company that outfits utility and work trucks with beds and boxes. These are just large custom
>  “truck boxes” 
> 
> -With smaller banks, I have successfully retrofitted both gang boxes and truck/utility boxes. The simplest setup being adding some cross members to a  
>  $300.00 gang box so that the batteries sat elevated within. That makes a very nice servicing height! Again interiors are coated.
> 
> Growing up, I had a lot of exposure to both industrial off-grid power systems (mining, oil/gas, research, telecomm) and Maritime systems and thats
> where my sensibilities originated. Lately I have found myself the sole off-grid specialist in a fairly vast area, and so what Im doing mostly is replacing battery banks. Lots of battery banks, and lots of rotten, corroded, nasty toxic boxes! A few weeks ago my helper and I donned Tyvex suits, rubber gloves,
> goggles, and respirators to Demo a box that was in a dilapidated and soon to be be razed structure. The general contractor and client stood by laughing and commented that it looked like a scene from Breaking Bad!
> 
> 
>> On Jan 28, 2016, at 9:18 PM, Ray Walters <ray at solarray.com <mailto:ray at solarray.com>> wrote:
>> 
>> Thanks for all the replies so far.  I've tried foundation waterproofing membrane for a couple of years, but found it will deteriorate in high acid concentrations.  IT gets all gooey and begins to dissolve.  It had peel N stick adhesive, and seemed like a good idea, until later.  (it was HDPE?) 
>> I've seen construction 10 mil plastic sheeting hold a gal of acid for many months, so I know that at least works for acid.
>> 
>> The pond liner looks good as well as Roy's wall plastic, but the 1/8" polypropylene would seem to be possibly more durable for about the same $$.  Plastic welding looks relatively easy with a heat gun and special tip on a soldering iron, too.  I'll report back on what we actually do.
>> 
>> As always thanks for the input, and I welcome all further comments.  I feel battery enclosures are a somewhat neglected part of off grid design. 
>> R.Ray Walters
>> CTO, Solarray, Inc
>> Nabcep Certified PV Installer, 
>> Licensed Master Electrician
>> Solar Design Engineer
>> 303 505-8760
>> On 1/28/2016 7:06 PM, frenergy wrote:
>>> Add to the list...I've had good luck with Grace roofing underlayment: tough and to a degree, self-healing, sticks to itself (and anything it comes in contact with) very well making seams secure, easy to find at building supply store, sticks aggressively to battery box sides without mechanical fasteners, experience has shown it resists acid.  As with other solutions, something to uniformly distribute the weight and irregular bottoms of batteries should be employed.
>>> 
>>> Bill
>>> Feather River Solar Electric            
>>> Bill Battagin, Owner
>>> 4291 Nelson St.
>>> Taylorsville, CA 95983
>>> 530.284.7849
>>> www.frenergy.net <http://www.frenergy.net/>
>>> 
>>> On 1/28/2016 5:35 PM, Allan Sindelar wrote:
>>>> Ray,
>>>> Just a couple of weeks ago we installed a 24V HUP set in an existing installation. We had an existing plywood battery box made of Baltic Birch (the 9-ply 12mm thick plywood typically used for cabinet drawer carcases) with a liner made of 40(?)-mil pond liner material. We removed the six cells from the steel case, set the case in place in the plywood box and lowered the cells into it. However, the box had a non-removable 5" wide strip across the top rear, and we needed to slide the entire 1100 pound case back about 8" in order to fit both steel cases.
>>>> 
>>>> Before setting the steel case in the box I sprayed the floor of the pond liner with a layer of the new spray pulling lube from Klein Tools, then set the steel case in place and lowered the cells. Using a Porta-Power and some blocking, we slid the case into place with little effort. 
>>>> 
>>>> You might find that vinyl pond liner works well in a plywood box. We found it at a Home Depot.
>>>> Allan
>>>> 
>>>> Allan Sindelar
>>>> allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
>>>> NABCEP Certified PV Installation Professional
>>>> NABCEP Certified Technical Sales Professional
>>>> New Mexico EE98J Journeyman Electrician
>>>> Founder (Retired), Positive Energy, Inc.
>>>> 505 780-2738 cell
>>>> 
>>>>  
>>>> On 1/28/2016 3:25 PM, Ray Walters wrote:
>>>>> Hi All; 
>>>>> 
>>>>> We're looking to improve our battery box construction, and are considering using 1/8" think polypropylene sheeting.  I've used small premade boxes before, but this will be for a HUP install, and we would want to build the box around the batteries after.  Does anyone have experience/ comments on welding plastic?  The alternative would be to just seal the seams with acid resistant caulking. (silicone, Geocell, ?) 
>>>>> I've had good luck in the past just using 10 mil plastic sheeting stapled up on the inside of a plywood box, but we will be scooting 1000 lb batteries around on it, so I don't think the sheeting will hold up. 
>>>>> 
>>>>> Thanks, 
>>>>> 
>>>> 
>>>> 
>>>> 
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