BMW UK – including MINI – has partnered up with Off Grid Energy to breathe new life into spent batteries from the brands' PHEVs and EVs. Rather than going off to be stripped and recycled, they will instead be repurposed to provide off-grid, portable power for a variety of purposes – including mobile chargers.

With BMW rapidly scaling up its EV and PHEV fleet, including the much-anticipated BMW iX3, in the coming years there will be a lot of batteries reaching the end of their useful lives for powering cars. And it's an issue which will only get more pressing in time, with the Group aiming to have 25 electrified models – half of which will be EVs – on the road by 2023.

But, like with other brands, the problem of surplus batteries is also a potential blessing by reusing them in 'second life' applications. This is where Off Grid Energy comes in.

The UK company specialises in providing clean, sustainably-produced power for off-grid settings including construction, utilities, events and remote locations. Since 2011 it has been working with an array of high-profile organisations, charities and – importantly – automotive brands. In fact, the company boasts one of the largest fleets of energy storage units in the world, with its devices predominantly working on the basis of intelligent generation and battery storage. This means some are charged from the grid and then transported to provide power away from it, or use on-board generators to charge, before turning them off for quieter and lower-emissions use.

BMW and MINI's partnership will see the Group supply Off Grid Energy with batteries from its EVs, to be used – perhaps slightly ironically – in creating a module to use for off-grid EV charging.

A prototype is already up and running. Using lithium-ion battery modules from a MINI Electric the charger has a capacity of 40kWh and can charge an EV at up to 7.2kW – equivalent to a regular on-street AC charger. To prove the concept, it will be used at BMW and MINI events over the next 12 months.

Obviously, at the moment even older electrified BMW Group cars are relatively young, and the company warranties its batteries for eight years or 100,000 miles. Even after this period a battery will likely have 80 per cent of its original capacity remaining and continue to be effective for a number of years more. However, there will inevitably come a point where a replacement is sensible.

When the supply of spent BMW batteries does start ramping up, Off Grid Energy is already planning to up-scale its charging system. In time, it wants to build an off-grid charger with up to 180kWh of capacity, providing multiple chargers capable of delivering power at up to 50kW – or the equivalent of a public fast charger.

As with all second life applications for EV batteries, extending their useful life will elongate their ability to deliver a negative carbon balance. Whilst it varies per manufacturer, an EV will typically pay back its carbon debt after around 30,000 miles – or around three years' driving for most people. Add ten years to that figure and you have a large negative carbon balance. What's more, EV batteries are almost 100 per cent recyclable.

Danny Jones, Managing Director Off Grid Energy said: “Off Grid Energy’s business model has been built with sustainability at its core, from the way we make our products and the materials we use, through to the environmental impact of our technology. We’re extremely excited to be in partnership with BMW Group UK and use our technology to give BMW and MINI electric vehicle batteries such a valuable second use.”

Discover EV's take

With the UK lacking in battery recycling capacity, and second life being a far better use of 'spent' cells, BMW's partnership with Off Grid Energy is a welcome one. In the popular media you don't have to search hard to find someone making derisory comments about charging EVs off-grid, and the difficulty in doing so. This solution is a step in the direction of answering those critics.