If Tony wants to move away from diesel equipment he shouldinvestigate this product now. Though everything about the
technology is being down played and hidden, (at least regarding
the zinc air or lithium air, electric car) while older lithium battery
technology recoverse R&D costs. Before the industry moves and
license everywhere the next generation lithium air and zinc air
batteries, actually utilizing air as energy contribution to the battery's
power, efficiency, driving distance and life cycle.
https://www.ecochunk.com/1339/2012/07/26/eos-energys-160kwh-zinc-air-battery-could-end-range-anxiety/#more-1339 
The in article, company link, is erroneous, and not a british company
but US. Not mentioning much or anything about the air breathing
battery for electric cars.
It's this, which I believe is an all US company.
https://www.eosenergystorage.com/custom/automotive-2 And this news on the page about the zinc air battery. I think
other companies are trying to make it lithium air too.
https://www.eosenergystorage.com/energy-storage-update-zinc-air-and-frozen-air-move-forward/ The site use to be a lot better and more professional than this, as
if hiding itself from the world, and only approaching companies on
its own as its main way of promotion and selling. The last news
link appears to be 2013, just after they were involved in testing the
zinc air car above in 2012. Now sitting on everything publicly and
emphasizing privately the storage capacity and storage use of the
zinc air batteries.
Sound familiar a la Tesla's wireless Tesla Coil technology, technology
getting with everything from wireless energy, to antigravity technology
teleportation, aethericity and not electricity moving in wires and wireless
and overhaul of all physics, metallurgy, medicine, cosmology, you
name it. Being sit on for 100 years now.
I doubt zinc air and lithium air, batteries, for cars and other commercial
and house hold gadgets, plus storage and industrial use, like
gold mines, will be sat on much longer.