Nuvation Energy’s battery management solution, powered by ADI

Stationary energy storage leader Nuvation Energy offers a configurable battery management system that supports a wide range of chemistries, allowing owners to source batteries from multiple sources, including spent electric vehicle batteries.

Energy storage systems (ESS) are essential in transitioning to a renewable-based, decentralised energy grid. They play a critical role in addressing the challenges of the intermittent nature of renewable energy sources and satisfying the increasing demand for energy by electric vehicles (EVs).

By storing excess electrical energy in batteries and releasing it during peak demand, ESS helps stabilise the grid by balancing energy supply and demand.

Ensuring ESS efficiency, from batteries and control systems to connectivity infrastructures, requires a safe, reliable and scalable battery management system (BMS). Innovation is needed to advance ESS capabilities, increase operational reliability, strengthen preventative safety measures and reduce the total cost of ownership.

For its next ESS innovation, Nuvation needed a trusted partner. It chose Analog Devices, Inc. (ADI), an industry leader known for its deep domain expertise, extensive field support and precision BMS cell monitors to help solve Nuvation’s new technical problems, cater to market need, and facilitate getting to market faster.

A shared vision for the future

Nuvation Energy and ADI have worked together for a decade. In 2021, the Nuvation-ADI relationship accelerated when both companies recognised they shared a vision for the future, including reusing EV batteries in second life and expanding the electrification ecosystem.

Nuvation turned to ADI to collaborate on its next advance, Gen 5, targeting the ESS equipment and offering high and low voltage BMS designed for long-term reliability. Over the next two years, Nuvation worked closely with ADI as its trusted partner to integrate past technical accomplishments and solve new issues, covering:

• A comprehensive range of voltages and temperatures – Nuvation selected ADI’s LTC6811 high precision cell monitor to integrate with its BMS. Working together, the technologies can more accurately monitor and manage high and low voltages (from 60V to 1,500V) and higher energy-density lithium batteries. Nuvation’s cell balancing and state of charge algorithms help maximise the usable capacity of the batteries and decrease system downtime.
• Multiple battery profiles and chemistries – ADI’s BMS cell monitor sensors enabled Nuvation to develop a flexible battery management solution that could be programmed to support the voltage and temperature ranges and charge/discharge profiles of many types of batteries. The sensors also allow ESS providers to source batteries with different chemistries and capacities from a wider pool of vendors.
• Integration – Nuvation Energy’s BMS prepares ESS installations for future augmentation, as newer batteries with newly designed management profiles and chemistries may be added, and its configurability helps simplify the integration of these batteries.
• Support – Nuvation’s BMS solution supports lithium-based batteries, as well as batteries employing other chemistries. Lithium-based primary batteries are more expensive than other chemistries but are optimum for energy storage and faster charging. Low use secondary batteries, added for redundancy, allow for more cycle time. They use cheaper chemistries but may require longer charging times.

Passive vs continuous cell balancing

The time an ESS spends in downtime during battery charging can be costly to the system operator. Reducing downtime and avoiding damage during charge and discharge cycles are essential for a productive ESS.

The following presents two methods for balancing cell charge and compares efficiencies:

Passive cell balancing utilises voltage change data acquired at the top of the charge cycle. Depending on the amount of imbalance in the batteries, this may result in a reduced operation period for the ESS as cell balancing brings all the cells to a full charge. The BMS monitors cell voltage and temperature and provides crucial data to the power conversion system (which converts AC to DC and vice versa) to help ensure it does not damage the batteries during charging and discharging and initiates preventive safety measures when needed.

Continuous cell balancing utilises Nuvation’s G5 BMS and ADI’s precision measurement technology. Cell imbalance is periodically estimated when the fastest charging cell reaches 100% state of charge. Nuvation’s BMS balances the remaining cells during system operation. This process enables the ESS to resume full operation quickly.

A second life marketplace

After 8 to 10 years in an EV, the battery packs retain 70% to 80% of the original charge capacity. This can be leveraged for up to an additional decade in stationary ESS applications.

ADI’s precision cell monitors help build trust between EV battery buyers and sellers. They provide accurate cell voltage and current data to determine the battery’s state of charge across its lifecycle and as the battery comes out of EV operation into the second-life marketplace.

“An EV’s BMS is designed specifically for use in an EV. While appropriate to that use, better performance and scale can be achieved with a BMS designed for stationary energy storage,” said Michael Worry, Nuvation Energy CEO.

“Our customers choose Nuvation Energy’s BMS for second-life applications in stationary ESS because it’s specifically designed for ESS, allowing for that improved performance and scale.”

There are clear economic and environmental incentives for nurturing a secondary battery market – a critical component of Nuvation and ADI’s shared ecosystem strategy.

Organisations that manage high volumes of used batteries can create new revenue sources where batteries can be repurposed to store excess power generated by wind and solar.

The total cost of ownership is reduced as the lifetime value of a battery – ~30% of the cost of an EV – is amplified. Extending a battery’s life also puts less stress on mining raw materials and decreases the number of batteries going into landfills.

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