# Building battery boxes: welding and design



## Tremelune (Dec 8, 2009)

I'm nearing the point where I'll need to start stuffing EV components into my project, and my fabrication skills are near zero. I plan to hire pros for mission-critical welds (subframe, motor mounts), but for battery boxes and brackets here and there, I was planning on giving it a whirl myself.

I'm a definite beginner, but I'm comfortable with a MIG welder. I was planning on buying a Millermatic, but they're fairly pricey, and I wonder how much welding I'll do in my life outside of this project. Is there a cheap decent alternative? Stick welding? Seems simpler and perhaps good enough. I like aluminum for lightness, but then I couldn't weld stuff to existing parts of the car.

Is there a better place to ask this question that is more focused to fabrication and battery box design? I was just gonna slap some angle-iron together in a cube, and bolt the batteries inside. If I put batteries in the engine bay, it seems wise to have the batteries in some kind of waterproof container, but then I begin to worry about heat dissipation...

Any good links for designing and building battery boxes...?


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## jonescg (Nov 3, 2010)

What is the space available? Is it broad and not very high? Or is it tall with a small footprint?

I managed to fit 18 kWh of battery in the space of the fuel tank of the Honda Prelude with room to breathe, but the Mini is a fair bit more compact than this.

So long as everything is separated from the cabin, and waterproof, you are probably best off working to the shapes available, and attaching to as many existing pickups as you can.


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## latimer (Aug 29, 2018)

For a project this small, you can go with a small Chinese IGBT-based welder. A few have been tested by welders on Youtube and will require some adjustments, but are pretty good for small jobs. 

MaksWerks Reviews - $300 250 Amp Chinese MIG Welder

THE CHEAPEST "MIG" WELDER ON AMAZON - REVIEWED!!!



As far as building battery boxes is concerned, take a look at this video series done by ZeroEV


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## nicolaskn (Feb 27, 2019)

I picked up a Klutch ST80i from northen tools on sale for about $160. Should be good enough for you to build a battery box. I'm using my welder for mounts for accessories and controller that way I can have a bolt in system in the event I ever plan to scrap the car to someone who wants to use shell with gas engine.

I did as you and sent the motor cradle to be welded professional.


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## x.l.r.8 (Oct 20, 2018)

The real question is exactly what you have asked. Yes a cheap welder will be adequate, a used mig will be better, gass less welding is never ideal and material and prep makes a lot more difference than the name on the box. That being said there is a very important number stamped on the box and it’s duty cycle. Especially if you start to weld more and more. I started off with a portable Sip welder, 6 months later it was deemed useless. I ended up spending a fortune on a censors 160 mig and 30 years later it’s still amazing. It’s heavy and a pain to move around, it’s HUGE and newer mugs are 1/3 of the size but is 80% duty cycle at full power means I can weld all day. Personally I would look for a used mig with a decor to duty cycle and enjoy cleaning metal to spotless condition and learning to weld. Then if you find it’s no longer doing the jobs you need then weigh up farming out the work or buying something that will last a lifetime. A selection of old angle grinders with wire brushes and flap wheels would be a better investment than a shiny new welder in my opinion.


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## Duncan (Dec 8, 2008)

Back in the day when dinosaurs roamed the earth you could easily tell a good welder - it was the one you could NOT pick up

Today with inverter technology that is no longer true - I bought a medium quality MIG about 2 years ago - about $600US 

Compared to the ones I used 30 years ago it's a miracle!! - the inverter technology and all of the rinky dinks about starting the arc make it incredibly EASY to use


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## CanadaLT28 (Oct 15, 2011)

I am just starting the battery box as well, big enough for 4 Volt packs (but installing 2 for now). I have bought an Everlast MIG welder and it was the best thing I could have done. Good price and good service (if needed, mine did). Use the Argon/CO2 gas mix as you will get a much better weld then a flux core.


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## Tremelune (Dec 8, 2009)

I watched a bunch of videos on stick welding, and it seems like a good compromise in terms of cost/complexity, skill, and versatility. Equipment is about half the cost vs MIG, you can use it for steel, aluminum, and others, and the learning curve is shallower.

The main downside is slag, uglier welds, and difficulty with thinner-than-one-eight-inch metal...I'm not too concerned about that presently. This is probably the route I'll go for a toe-dip into fabrication.


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## CanadaLT28 (Oct 15, 2011)

Tremelune said:


> I watched a bunch of videos on stick welding, and it seems like a good compromise in terms of cost/complexity, skill, and versatility. Equipment is about half the cost vs MIG, you can use it for steel, aluminum, and others, and the learning curve is shallower.
> 
> The main downside is slag, uglier welds, and difficulty with thinner-than-one-eight-inch metal...I'm not too concerned about that presently. This is probably the route I'll go for a toe-dip into fabrication.



MIG is easiest if you are a newbe and the cost difference is not that much.


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## jonescg (Nov 3, 2010)

I bought an old buzz-box stick (SMAW) welder from the Quokka (like Craigslist, only Perth specific) and I've learned how to weld satisfactorily. It's only good for steel (stainless is OK) but I wouldn't bother trying to weld aluminium with a stick welder, no matter how good the fancy rods are. It won't be as pretty as a TIG welder and probably not as strong.

I found you can weld 1.6 mm steel tube is you are very careful and put some effort into not blowing holes, but it's always good to gusset any junctions anyway.


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## DrGee (Aug 22, 2018)

How about building a battery box out of wood? Including fireproof lining?


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## arber333 (Dec 13, 2010)

DrGee said:


> How about building a battery box out of wood? Including fireproof lining?


Yes, wood is good material. Nice to work with and intelligent regarding moisture. 
A friend made a wooden battery box for his electric boat couple of years back and i think it still works. 
In my EV i use exclusively wooden plywood cover for my rear battery box. From 15mm ply it is stiff and i can load it with stuff and i dont fear for my cells underneath.

I wouldnt recommend you just strap your battery box in your EV. Think about where the fittings would go and then make them from either Alu or steel and temporarily screw them on. Then i would recommend you glue them in with epoxy glue and use bolts to fit them in your chassis.

For box floor i would recommend you use rubber mat 3mm to keep things isolated even in case moisture would come through.

EDIT: Plywood is excellent chrashworthy material. It crumples on impact draining energy and leaves no sharp points whereas carbon or fiberglass are more risky in that regard.


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## Shebang (Aug 30, 2019)

How much space is available?


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## DrGee (Aug 22, 2018)

arber333 said:


> DrGee said:
> 
> 
> > How about building a battery box out of wood? Including fireproof lining?
> ...


think these are good points here. Especially the part about securing the metal fixtures to the wooden box with both screws and epoxy. In the right environment, wood can give metal a good run for the money


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