Lithium Battery Storage for Lift 4 Efoil Battery

Fireproof(ish) vented metal box with legs for storing lithium battery from a Lift 4 efoil.

Cost was about $100 USD, less than a third of the $350 USD charged by Lift for its battery case. Other people have used military-surplus ammunition cases for this purpose, but these are hard to find and quite expensive in Canada.

It's important that a lithium-storage case be vented, as in the event of a fire, a fully sealed box can burst from overpressure, possibly resulting in a narrow jet of flame being emitted.

See video here.

The electrical box I used for this has a bottom plate intended as a cable pass-through; with some washers as spacers, this was made into a vent.

Warning! This box has never been tested with a fire, so I can't vouch for its effectiveness in the event your lithium battery ignites. I feel that it ought to keep my house burning down, but you'll need to judge for yourself before you trust it.

a) Steel Electrical Junction Box. Brand name Vevor, size 20 x 16 x 6'', IP66 waterproof.

Cost $119 CAD. You could use other similar boxes instead, but watch out for the size of the box opening rather than just its exterior dimensions. This box has an opening of 45 x 35 cm and an internal depth of 15 cm, which was just big enough to accommodate the battery.

b) 4 x ABS caps, 1.5"

c) 4 x fender washers

d) 12 x 0.5" washers

All the remaining hardware (bolts, nuts, panel) came with the electrical box.

Remove the backing plate from the box. Discard/recycle it.

Drill holes through the centres of the ABS pipe caps.

Attach the inverted ABS pipe caps to the back of the box using the fender washers and the nuts and bolts that came with the box. The legs make it easier to grab and move the box when the heavy battery is inside.

Attach the metal panel to the opening at the bottom of the box with the screws provided. Do not use the gasket, as this will make the panel opening more-or-less airtight, and you want it to be able to vent in case of a fire. Rather, put one or two small washers between the box and the panel at each screw to create a small gap around the edge of the panel.

IMPORTANT: The Lift 4 battery is much larger than a typical ebike battery, with a capacity of more than 2 kWh. If a battery fire occurs, the box will get extremely hot and there will undoubtedly be sparks. Even if no flames escape, then, it's likely that any nearby flammable materials will be ignited.

So keep your lithium battery box somewhere like in the middle of a concrete floor. I have a fireplace I never use, so the box lives there. I hope I never have to find out whether this works or not!