Prismatic Battery Box and Clamping Ideas

2710 Views 2 Replies 3 Participants Last post by electro wrks, Nov 16, 2017

goingbush

Discussion Starter · Nov 14, 2017

I have ordered (and paid for) 46 x Sinopoly LFP 200 AHA cells for my EV Build so now I need to get off my butt and build some battery boxes.

I am doing so in accordance with Australian National Standard NCOP14 which states

2.3 Battery Restraint
The batteries that power the vehicle must be fixed in position so that they will not easily break free in a crash and thus create a hazard to the driver, passengers or other road users. The battery restraint system must adequately withstand at least the following crash accelerations:

Front impact 20 g (i.e. 20 times the battery weight);
Side impact – – – – 15 g;
Rear impact 10 g; and
Vertical (rollover) impact 10 g.

An impact sensing (G force) switch should opened in the event of an impact.
Battery restraints must be designed so that during fitting and maintenance operations, either the restraints or any tools required cannot easily provide a short circuit path for the battery terminals or other exposed wiring and connections. Similarly, it is recommended that insulated tools are used for fitting or maintenance operations.

I will have 4 battery boxes, one box for example contains 12 cells @5.8kg = 70kg , which must be able to sustain a 20g frontal impact = 1.4 tonne force on the battery box (, obviously any Human will be dead after a 20g Impact so really its a moot point if the batteries survive or not .) My EV is a 4x4 and though I think the posted G Ratings are Excessive I don't want my cells bouncing around on rough tracks.

Most pictures of Prismatic battery enclosures Ive seen would not be able to sustain such loads, And even some Australian EV's I've seen that have passed Engineering inspection don't seem to comply, for example using Thule straps to hold down the cell packs, i would not have thought acceptable.

I have not decided yet but thinbk I will make my boxes from Polypropylene with Lexan lids & Steel girdle around to comply with the load rating

Can people please share photos of their battery box, clamping / hold down ideas , below is one I found by googling but it wont work in my situation as space wont allow.

Image from http://www.mightyboyev.com/Battery Upgrade October.htm

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Duncan

· #2 · Nov 14, 2017

Hi
here in NZ those high specifications are for a battery inside the passengers compartment

My interpretation is not that the batteries won't move under those loads but that they won't escape under those loads
Which is a bit easier to achieve

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electro wrks

· #3 · Nov 16, 2017

goingbush said:
I have ordered (and paid for) 46 x Sinopoly LFP 200 AHA cells for my EV Build so now I need to get off my butt and build some battery boxes.

I am doing so in accordance with Australian National Standard NCOP14 which states

I will have 4 battery boxes, one box for example contains 12 cells @5.8kg = 70kg , which must be able to sustain a 20g frontal impact = 1.4 tonne force on the battery box (, obviously any Human will be dead after a 20g Impact so really its a moot point if the batteries survive or not .) My EV is a 4x4 and though I think the posted G Ratings are Excessive I don't want my cells bouncing around on rough tracks.

Most pictures of Prismatic battery enclosures Ive seen would not be able to sustain such loads, And even some Australian EV's I've seen that have passed Engineering inspection don't seem to comply, for example using Thule straps to hold down the cell packs, i would not have thought acceptable.

I have not decided yet but thinbk I will make my boxes from Polypropylene with Lexan lids & Steel girdle around to comply with the load rating

Can people please share photos of their battery box, clamping / hold down ideas , below is one I found by googling but it wont work in my situation as space wont allow.

Image from http://www.mightyboyev.com/Battery Upgrade October.htm

It good to pack the cells tightly in a box. But as they age and swell, as most seem to do, it might be nearly impossible to remove them with out cutting open the box. A better design would be to have a simple sliding bulkhead(s) with adjusting bolts that pushes the bulkhead(s) to clamp the cells in place. When the cells need to be removed, loosen the bolts and bulkhead(s) and the cells will easily come out.

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