Two Irish engineers are focused on a big project: to turn old car batteries into green power units. The duo aim to replace petrol and diesel generators with a range of products powered by repurposed electric car batteries. 

The Range Trailer is an Irish made mobile clean energy platform for use on farms, mobile retail, businesses or home. Built with a second-life battery pack, this innovative high-capacity energy storage unit (24-72kWh) makes it easy to harvest power when it is free (solar) or low cost and to use it at peak. It also makes an ideal back-up 'generator'. 

The devices, currently at prototype phase, are made from old, repurposed batteries and can store energy for up to a year, which means users can avoid paying peak rates to fire up generators. They also require no maintenance, and offer a cleaner alternative to petrol and diesel.

Range Trailers are programmed to check the weather forecast and decide whether to charge overnight using cheap night-rate electricity or to wait and use solar-powered energy the following day. The product has been shortlisted for an Innovation Arena award from Enterprise Ireland.

Circular economy

Recently displayed at the Ploughing Championships, Minister Ossian Smyth TD described it is an excellent example of the circular economy. "Range Therapy, the Irish company behind the innovative product, is pioneering the reuse of Irish-owned large battery packs, for a range of storage options," he said.

"This capacity to reuse Li-ion battery packs will be so important in the future as we transition to sustainable transport and a wider sustainable energy ecosystem.”

Minister Ossian Smyth TD cuts the ribbon on Range Trailer with a power tool, powered by Range Trailer of course.

Eamon Stack, co-founder and managing director of Range Therapy, pointed out that with energy cost and energy security being such a major issue these days, the purpose of Range Trailer is clearer than ever: “Giving farmers, and many more people, a way to store a large amount of electricity means they can make significant cost savings, help the environment and do a great favour for the national grid. 

"It makes perfect sense to invest in a large solar project once you have a Range Trailer to store the power. For example, 18,000 dairy farmers milk their cows at 4pm each day – just at peak demand for the national grid. Range Trailer would allow them to store off-peak low-cost electricity and use it to power their machinery at grid peak.”

War has focused people’s minds

Dr Barry McMahon, co-founder and director of Range Therapy, said: “While the climate emergency is our biggest challenge, it seems the short-term energy crisis, caused by the illegal invasion of Ukraine, has focused people’s minds. 

"We are proud to design and build this innovative Irish product. And the static version is as important as the mobile unit – same great technology. The next stage for Range Trailer is to link several of the products in a local area and build a Virtual Power Plant (VPP). Already successful in many countries, a VPP can offer the national grid another alternative to expensive and polluting peaker plants.” 

According to the Business Post, the two inventors are aiming to raise at least €500,000 to develop a series of products they believe can replace petrol and diesel generators with a cheaper, more environmentally friendly alternative. 

The idea underpinning their firm – which is not a commercial entity, they said – began more than 15 years ago, when they began equipping older electric motorbikes with newer batteries. 

'Upgrade the battery packs of older Nissan Leaf cars'

“Over time, we started to do the same thing with cars,” Stack told the Business Post. “We started working with a business in the Netherlands to upgrade the battery packs of older Nissan Leaf cars in Ireland.”

“We grasped that there were going to be a lot of second-hand batteries available – within five years we will have 10,000 used batteries available every year, in Ireland. And that will go up to 50,000.

“So on the one hand we have the problem of how to get rid of the batteries that are no longer suitable for cars, but that are ideal for energy storage. And on the other hand we have needs – we need to get rid of noisy diesel generators, and we want to have fast chargers for cars without having to draw on the grid all the time.”

Recently, the firm launched a line of products designed to meet both of those needs.

Eamon Stack.

Static version of the same product

As well as the mobile units, Range Therapy is also developing a static version of the same product, which uses the same technology but can be bolted to a wall.

Stack and McMahon are not seeking to make money out of their invention – “we’re not out for a fast buck”, says Stack. But it believes the company can become profitable and is targeting social investors as part of its funding round.

It is also working with Enterprise Ireland and expects the government to invest in its technology in order to scale up production and move to market.

“The challenge for us is that our prototype has to be translated into production in the next two years,” says Stack.

“Our product is a significant benefit to the government and can help it to deliver on its own climate policies. So we would expect the government to be a significant funder.” 

Range Trailer: Four main uses

  • Just Power – no peak rates: technically called “peak shaving”, this massive energy store means you never pay peak rates: and energy is free if you have solar excess to recharge!;
  • Just Power back-up – no maintenance: this power back-up, technically called Uninterrupted Power Supply UPS, requires no maintenance contract;
  • Just Power for mobile retail – no pollution: this powerful portable generator (5.5kw – 22kw AC) makes no noise, no fumes or no CO2 + no big fuel bill!;
  • Just Power to charge EV – no queue: fast charge your EV (CCS or Chademo) @20kw or bring your own fast charger on holidays. 


  1. Low cost energy – charge with solar PV or off-peak rates – four times cheaper than petrol generator;
  2. Zero carbon emissions – fume-free; CO2 free;
  3. Zero fumes and particulate matter;
  4. Silent operation;
  5. High-capacity storage : 24kWh to 60kWh;
  6. Second life battery – circular economy;
  7. Portable or Static – your choice;
  8. Fast charge the trailer option – AC 6.6kw (future DC fast charging option);
  9. Another reason to instal solar;
  10. It’s Irish. 

More about the Range Trailer:

  • Charge Range Trailer with solar or off-peak night rate

The best use of a solar investment is to store all the excess power and use that energy 'when the sun don’t shine'. Range Trailer offers large capacity storage, enough to power your business or home for days.

  • Static storage and clean power

Static storage is known domestically as a 'powerwall' or commercially as an Uninterrupted Power Supply (UPS). Range Trailer technology is available in a non-trailer format to serve this purpose. The battery pack and inverters can be attached to a wall and integrated into the commercial or domestic energy system.

  • Intelligent energy decisions

Its RangeSoft application reads the state of charge of the battery, checks the weather for tomorrow (if you have solar) and decides how much off-peak power to add to the battery. We call this  our 'ain’t no sunshine in the morning' algorithm. 

Back story

"We have been co-funded by the Local Enterprise Office in Kildare," says Stack. "We built the Range Trailer in the county with an expert designer and welder. The main components are the trailer, the main frame, the shock absorbers, the inner frame (with suspended battery pack), the technology floor (inverters and relays) and the touch screen UI." 


  • 24kWh: €10,000
  • 40kWh: €15,000
  • 80kWh €20,000


EV Fast Charging: €7,000
Trailer Fast Charging: €1,200


Monthly: €500-€1000. 

Clear advantage  

Reuse of Irish EV Batteries for EVs, Range Trailer and Powerwalls

"The Range Trailer has a clear advantage over other storage devices – it reuses battery packs from EV," says Stack. "This is the circular economy in practice. We don’t just reuse the battery cells. We use the modules, the BMS (battery management system) and the complete CAN monitoring built into an EV. We source inverters and relays from used EV where possible." 

Domestic Energy Storage Unit – the 'powerwall'

"The same circular economy strategy and technology will be found in our Domestic Energy Storage Unit – the 'powerwall'. You can use the portable unit if you have space for the Range Trailer, or you can bolt the battery to your wall and fit the technology in a neat cabinet.  

"The Domestic Energy Storage Unit is web enabled and you can monitor and control it from your favourite mobile device: phone or tablet or laptop. 

"Our 'Ain’t no sunshine in the morning' software is our magic sauce. This checks the weather forecast at  midnight, and based on the current state of charge of the battery and expected load tomorrow, decides how much low-cost night energy might be needed to top-up battery." 

First Irish EV battery extension

  • "We have brought back three Muxsan kits for installation in Ireland," says the company. "The first Irish Muxsan installation has already been done in Barry’s own car. His 2011 Leaf went from range of 87km to 217km (on the clock but 197km on a long trip). Emile of Muxsan was impressed that we completed the installation without needing any intervention from Muxsan.
  • "Eamon has received further training on the Leaf Gen 2 upgrades. The Gen 2 upgrade is slightly easier than Gen 1, due to improved wiring by Nissan (the Muxsan electronic connection to the Leaf are plug and play). And there is more room in the Gen 2 boot to fit the extension battery in one single 18cm layer."

Battery packs hold value for years

"We want to emphasise that adding a battery extension pack to your Leaf is a long-term investment," says Stack. 

  • Your Leaf becomes a 40kWh EV and will be more useful and valuable;
  • The longer the car is kept on the road the greater the reduction of its annualised carbon footprint – no more 10 year scrappage as EV last 25 years;
  • The new battery pack is very valuable high-quality Li-ion pack with in-built BMS. It will retain much its value for up to over 25 years. Its first life will be in your Leaf but it can continue life as a Powerwall or grid storage asset long after the car passes its viable life;
  • Upgrading these early EV will improve its 'witness' value. Many people use the poor range of early EVs as an excuse not to consider an EV – you are an early adopter and a very important ambassador for EV adoption.