Thickness of Stainless Steel Or Normal Steel For Battery Box?

thinkingblue

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Jun 28, 2021
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0.98mm stainless steel or 1.2mm steel? Same price. Getting a battery box made by amys supplier.
Box size L580mm * W300mm * H360mm.
Box is so big because i was leaving room for 5cm thick Pir insulation i have for UK cold nights and recharge in morning use.

So there not so cold on winter, early spring, autumn, evenings, night and in the morning i guess more quickly reach temp for recharging in morning sun.
If need be, i would research adding heating pad. Thought such thick insulation would add impact protextion too xd. Already got enough off cuts off it. So its not a addition cost. Does make the box a lot bigger!
 

newbostonconst

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Stainless unpainted looks nice as long as they weld it with stainless welding wire.....What grade stainless...Some stainless still rusts.
 

thinkingblue

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im not sure if they weld it. laser cut and maybe folded and rivited? I dont l know much about stainless grades. so no idea. had wondered i guess ill just ask. each question takes ages to get a reply. hmm
 

Zwy

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0.98mm stainless steel or 1.2mm steel? Same price. Getting a battery box made by amys supplier.
Box size L580mm * W300mm * H360mm.
Box is so big because i was leaving room for 5cm thick Pir insulation i have for UK cold nights and recharge in morning use.

So there not so cold on winter, early spring, autumn, evenings, night and in the morning i guess more quickly reach temp for recharging in morning sun.
If need be, i would research adding heating pad. Thought such thick insulation would add impact protextion too xd. Already got enough off cuts off it. So its not a addition cost. Does make the box a lot bigger!
Make certain you plan for adding a heating element and controller for it.

If it is the same price, stainless is always the way to go but stainless is heavier. Did they quote aluminum?
 

Fast1one

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Stainless is barely heavier ~2%.
Stainless will always be heavier than carbon steel because the specific strength is lower. And it will be more than 2%, properly engineered. The yield strength is lower than carbon steel.

The specific strength (yield strength/density) is 27% higher for carbon steel versus stainless steel based from that table. You would have to go up a gauge or two to make up the difference. Aluminum has a specific strength that is 50% higher than stainless steel. But there are other considerations, such as fatigue strength and manufacturability.

Wood actually has quite high specific strength which is why it is used often in RVs. But it isn't great in bending and it tends to catch fire 🙃


Regarding the original question, without doing any actual engineering (just a feel) I would opt for at least 18 gauge (~1.25mm) or preferably 16 gauge (~1.5mm) stainless steel assuming it is properly supported for long spans. You can probably go down a gauge for carbon steel or double the thickness for aluminum.
 

noenegdod

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im not sure if they weld it. laser cut and maybe folded and rivited? I dont l know much about stainless grades. so no idea. had wondered i guess ill just ask. each question takes ages to get a reply. hmm
Stainless.
304 or 316. Dont let them give you 4xx series.
Dont let them rivet.
Tig/spot weld only.
Material strength between the two is irrelevant.
 

thinkingblue

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Jun 28, 2021
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Thanks for your replys! :D
Seller replied:
So sorry, stainless steel box, they have only two choices: 0.88mm and 0.98mm thickness
gb1017760126:
Also what grade of stainless steel are they thinking of using?
Is box being welded together with stainless welding wire?
Thank you
----------
I will confirm with them

So it looks like i will be choosing for 1.2mm steel after all.
 

thinkingblue

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Jun 28, 2021
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Make certain you plan for adding a heating element and controller for it.

If it is the same price, stainless is always the way to go but stainless is heavier. Did they quote aluminum?
I asked but box maker recommend steel or aluminum was not a option. i forget. Been corresponding for months!
 

noenegdod

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Make certain you plan for adding a heating element and controller for it.

If it is the same price, stainless is always the way to go but stainless is heavier. Did they quote aluminum?
Nope. Some alloys are heavier and some are lighter. Units are kg/m3 Source: https://www.engineeringtoolbox.com/metal-alloys-densities-d_50.html

A block of SS that is 39" x 39" x39" of the heaviest SS weighs 17600 lbs and is ~300 lbs heavier than a block of carbon steel that weighs 17,270 lbs which means at the most SS is 1.7% heavier but on the other end SS can be 4.7% lighter. For a battery box, weight difference is irrelevant.

Stainless Steel 7480 - 8000
Steel7850
 

Zwy

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I asked but box maker recommend steel or aluminum was not a option. i forget. Been corresponding for months!
Around here, if you can't make it yourself, you go to the local welding shops and have them fabricate it for you.

Most have a press brake and shear and a TIG welder.

Personally, I prefer aluminum for less weight and no corrosion/maintenance.
 

curiouscarbon

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Jun 29, 2020
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just hopping in here to say that i intend on using oshcut to laser cut a 1.5mm or thicker sheets of stainless steel that would assemble together using aluminum extrusion along the edges. as long as the metal sheets are thinner than ~3mm they will fit perfectly into the T slot. then since i have no idea how to weld, i would simply seal the sheet/t-slot interface with silicone or something, running a continuous bead along all borders.

the aluminum extrusion would be held together using brackets and nuts and bolts.

either that or have the sheets have a flange bent 90 degrees on two sides and bolt onto a flat sheet.

using wood is appealing because it’s so cheap and available and easy to work, but why do it gotta be so flammable?
 
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