ReVolve™ battery systems

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Counties Energy hits its ReVolve™ second-life EV battery system milestone

Also covered by Counties Energy

Customer-owned electricity distributor Counties Energy and Australian battery technology company Relectrify are pleased to announce successful milestone results from their joint deployment of New Zealand’s largest battery system using repurposed second-life electric vehicle (EV) batteries.

First announced in December 2020, the energy storage unit has undergone robust testing in the last year. The battery system, now upgraded and referred to as the ReVolve™ battery system, combines Relectrify’s BMS+Inverter technology with batteries from nine Nissan Leaf electric vehicles to store over 120kWh of energy. In its new outdoor enclosure and following the successful existing validation, this and other ReVolve™ systems will be deployed on Counties Energy’s network once certification is complete.

The updated ReVolve™ system at Counties Energy’s site

The updated ReVolve™ system at Counties Energy’s site


The results shared here are based on 500 usage cycles of accelerated lifetime testing, equating to 50MWh throughput. A usage cycle here is when a battery discharges from around 90% charged to around 10% charged, and then charges from around 10% back to around 90% charged. This is also described as an 80% depth-of-discharge.

Key Result 1: 20% extra capacity unlocked

The capacity of a standard passive battery management system is usually limited by the lowest performing series battery cell in a series system. However, the ReVolve™ battery system is not constrained by this; instead, Relectrify’s BMS*+Inverter cell-level control technology was able to unlock an estimated 20% extra capacity in the second-life batteries during Counties Energy and Relectrify’s joint testing.

This was achieved by Relectrify’s BMS+Inverter hardware and smart algorithms taking a much more optimised approach; stronger battery segments with a higher state-of-health (SoH) contributed additional energy to the system, while gentler demands were placed on weaker battery segments with a lower state-of-health (SoH).

The result is an orchestra of each segment of the battery contributing at its own optimal performance, leading to higher-performing and longer-lived battery solutions.

Key Result 2: 88% Average Efficiency

Relectrify’s BMS+Inverter enables a grid-compatible alternating-current (AC) output as used in homes, industry, and the grid, without needing a separate costly inverter. Throughout the 500 cycles of testing, the full battery system achieved a round-cycle efficiency averaging approximately 88% AC-to-AC, including charge and discharge of the BMS+Inverter and of the second-life batteries. 

This efficiency compares favourably with real-life efficiencies of new industrial storage systems, such as 84.5% round-cycle efficiency for a Tesla Powerpack installation with the University of Queensland, Australia. 

Key Result 3: On track to validate the ReVolve™ technical lifespan of 3,000 cycles

The ReVolve™ battery system is projected to have a technical lifespan of 3,000 full charge and discharge cycles; this can be between 5 and 10 years of usage depending on how the battery system is used.

After 500 cycles at around 80% depth-of-discharge in accelerated lifetime testing, the battery continued to retain far higher capacity than a standard BMS would have been able to provide with the same batteries. 

“It has been great to see our extensive testing confirm that these batteries controlled by Relectrify’s BMS+Inverter meet the core technical and functional requirements required from battery storage, in a wide variety of applications relevant to Counties Energy as an electricity distribution utility,” said Moonis Vegdani, Counties Energy General Manager Technology and Digital. 

“It is outstanding to work together with Counties Energy to understand their industrial and utility use cases for battery storage, and to demonstrate in practice that battery systems powered by Relectrify technology meet their functional and performance requirements” said Relectrify Co-Founder and CEO Valentin Muenzel.

These successful testing results and the ReVolve™ completing its certifications accreditation will open up strong steps ahead. Counties Energy will deploy one ReVolve™ to a rural location on its network to solve power quality issues on the low voltage network, and two further ReVolve™ units as an energy buffer system for high-power EV charging at Mercer on the Waikato Expressway as part of an EECA supported project.

These project results and the next steps together are a strong example of how close collaboration between leading innovative companies can contribute towards creating a more sustainable future.



About Relectrify

Relectrify is a developer of advanced battery control solutions enabling lower cost and longer-lived batteries. Founded in 2015 and based in Melbourne, Australia, Relectrify works in strategic collaboration with battery manufacturers, integrators and companies deploying large volumes of new or second-life batteries around the world.

About Counties Energy

Counties Energy is a full-service energy solutions provider and the electricity distribution provider for the electricity network that runs from coast to coast across the southern Auckland and northern Waikato regions. The company is 100 percent owned by the Counties Power Consumer Trust who holds the shares on behalf of electricity consumers. The region is one of the fastest growing areas in the country, with the company upscaling the business to meet demand, invest in core business and new technology, from battery to smart grid infrastructure. For more information:


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