Higher power: Ford designs roof-mounted electric car battery, revealed in government patent files

Sometimes when a company patents a name, brand, image or technology, it's simply to prevent rivals from using it - but in the case of Ford's roof-mounted spare electric car battery, we're not sure anyone else was considering it.

Revealed in patent application drawings in the United States Patent and Trademark Office's published documents, Ford has designed a storage-pod-like, roof-rack-mounted spare battery which can be installed for long trips to recharge the EV's battery along the way without the need for a charging station.

It seems like a good idea in some ways, but there's a slightly confusing - probably obvious to most - aspect of this design.

Battery packs for electric vehicles are famously quite heavy, adding hundreds of kilograms to a car's weight when compared to ICE counterparts, so the idea of putting one on a car's roof is somewhat unexpected.

For a battery pack to be worth bringing along, mounted to a vehicle's roof, it would need to have enough capacity to add significantly more range than the pack's aerodynamic disadvantage and weight would subtract, and would need to weigh rather a lot.

On a forum for Ford F-150 Lighting owners where the patent was noticed last week - aptly called LightningOwners - several users expressed confusion and concern about the idea of a vehicle becoming too top-heavy.

It seems like a good idea in some ways, but there’s a slightly confusing - probably obvious to most - aspect of this design.

However, as might be expected, the post also points out something that Ford fans might have noticed - the patent drawing uses a Bronco for its example, which is currently not available as an electric car.

The patent filing goes on to explain that the roof-mounted battery pack can be installed or removed as needed, and can charge at home with a standard wall-mount and EV plug.

It also comes with a plug to charge the car it's mounted to, rather than being constantly connected to the vehicle's main battery - and also features remotely controlled valves to allow air through for cooling when in use, or to stop debris entering the pack while driving.