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When attaching a 90kg/210lbs battery box underneath my car (where the gas tank used to be) it seems like a good plan to make sure it doesn't fall off and slide underneath the car in case of a (mild) accident. Do DIY conversions normally take such things into account, and if so: how?

I can imagine both non-destructive (thick bolts, or clever cushioning) and destructive (crumple zone like) attacks.

What does the community think?
 

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What does the community think?
I don't think any significant efforts are made for gas tanks ... even 50+ Gallon tractor trailer gas tanks are rarely more than just a metal or plastic container.

And the Batteries contain a very small fraction of the energy potential of the gasoline.

Gasoline has ~36 kwh per Gallon... The potential energy EVs carry is a tiny fraction compared to what ICE vehicles carry.

I also know propane delivery trucks don't do anything more than put a single ratchet strap to hold a whole truck load of compressed combustable gasses.

I also know the vast majority of chemical HAZMAT transport companies for delivery or disposal ... also rarely do more than have several 55 gallon drums being held to the side of the truck with a single ratchet strap... sometimes if the 55 Gallon is full... it is delivered on a pallet and it is not secured inside the trucks at all.

In short ... we are already very comfortable with far greater risks... using next to nothing for safety devices.

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That having been said...

I recommend inertia triggered switches / relays / disconnects ... Ground fault detect , etc ... I recommend a chemical resistance and fire resistance battery box... I recommend catastrophic ventilation considerations.... I recommend knowing your vehicles designed crumple zones before you choose where to put components... I recommend designs that would rather sacrifice things... instead of people ( like me )
 

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When attaching a 90kg/210lbs battery box underneath my car (where the gas tank used to be) it seems like a good plan to make sure it doesn't fall off and slide underneath the car in case of a (mild) accident. Do DIY conversions normally take such things into account, and if so: how?

I can imagine both non-destructive (thick bolts, or clever cushioning) and destructive (crumple zone like) attacks.

What does the community think?
I think the average DIY battery box hanging under a car, with 1/8" steel angle iron edges, and plastic or plywood box, is probably WAY safer and stronger than a fuel tank full of gas. a little battery acid won't kill anyone (compared to gas). Probably BETTER if it breaks away in an acident ad shears cables, thus opening any circuit.

I am however NOT a fan of the throw-the batteries-in-the-backseat crowd. ;)



d
 

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There is a lot of mass to contend with especially with lead acid. ICE fuel tanks won't have as much mass and so can be held with a couple of steel straps and four M8 bolts. Oil is considerably lighter then lead.

The mounting for the batteries needs to be able to handle the static weight of the pack and also the dynamic loads when cornering and bouncing off speed humps and kerbs as well as collisions.

Also the individual batteries should also be secured to prevent them leaping about within the box or cage.

I think regardless of the lack of care or security of other hazardous materials we should ensure that our own house is in good order and avoid any potential (pun) for bad press.;)
 

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It IS a challange to find solid mount points for racking.... all the modern sheet metal floorpans are a bit flimsy. But, if care is taken to bolt down in multiple points and over reinforced areas, I'd say the steel edged racks make the whole car stiffer and stronger than OEM in some cases!
 
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