Supersize Battery Box

Go by the case size first, not the amp hours. Two batteries of the same capacity are often different sizes, so the number on the label tells you nothing about whether it will go in.

The internal size on each box page is the biggest rectangular battery that will sit in it. There is more height above that, but it is narrower than the box, and that space is for the terminals, the links between batteries and the cables running off them. Battery height is usually quoted to the terminals, so the figure on a spec sheet is often taller than the case itself. Measure the body of your battery, not the top of the posts.

The 95Ah box is 280 x 195 x 205 mm inside, the 160Ah box is 367 x 205 x 200 mm, and the Supersize is 532 x 271 x 270 mm. You can send us the make and model and we will tell you which box it goes in.

In a boat, a caravan or a camper trailer, yes. An unrestrained battery is a heavy object with nothing holding it in a hard stop or a big sea, and a bare positive terminal will find a spanner, a jerry can handle or a bit of chain eventually and start to short circuit damaging equipment and causing a fire risk.

The box does both jobs at once: it holds the battery still and it puts a lid between the terminals and everything else. In a fixed installation in a shed, where nothing moves and nothing can fall on it, the box protects the battery against dirt, moisture, animals, and accidental touching of the terminals.

That depends on the battery. A sealed AGM or gel battery is fine in a normal box. A flooded battery gasses while it charges, and hydrogen in a closed cabin is the one thing you do not want, so it must vent outside.

That is what the Supersize is for. It seals, and it comes with a clamp and a steel reinforced breathing hose so the gas runs out through the hull or the floor instead of collecting under the bunk. If the battery is flooded and it is going inside, use the Supersize and vent it. The hole and reinforced hose is also used for carrying electrical cables. If the box is placed underground or in other awkward or undesirable location, electrical cables can be transmitted through that, protected by the hose.

Yes. All three take lead acid, AGM and lithium. Lithium does not gas, so it has no need of the vented Supersize, but it still needs holding down and protection as impacts can cause fire and explosion and the case size is what decides the fit the same as with any other battery.