Rethink Energy had a chat with Californian start up Axiom Energy this week, which baffled our writer with talk of a “virtual” battery to help most US grocery chains to keep their food refrigerated, for less money. Turns out that talking to CEO Amrit Robbins, while Axiom once had the idea that a traditional lithium ion battery could help, it was the software which the company developed to leverage that battery which eventually became a virtual battery. Customers asked for the software without the lithium battery and he began selling licenses to it online. Its Axiom Cloud is simply a cloud app which initially takes input from store sensors, and collects these with its own instore hub, with a 4G…