[RE-wrenches] Battery Box Construction

Shasta Daiku mjmorningstar at gmail.com
Fri Jan 29 09:08:38 PST 2016


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> 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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