Case Study: The ULTRA Project

Supporting the introduction of next-generation battery cells with next-generation electric charging infrastructure.

In May 2020, UK Research and Innovation (UKRI) and the Advanced Propulsion Centre UK (APC) invited UK-based organisations to submit R&D project proposals. These proposals needed to accelerate the development of low- or zero-emission technologies whilst creating more jobs and capability within the UK supply chain.

Petalite partnered with a consortium of organisations developing and integrating next-generation Li-ion cells to provide a step-change in battery efficiency and performance.  Our role was to progress our next generation DC charging solution to offer the requisite reliability and scalability that the transition to battery electric vehicles (BEVs) will continue to demand.

The result of the project, known as ULTRA, was an increase in technological- and manufacturing-readiness across the consortium. At Petalite, we achieved power density enhancements and manufacturing efficiencies that are critical to the upcoming commercialisation of Petalite’s next-generation DC fast charging solution.

What was the objective of the ULTRA project?

The Ultra-powerful cells for Low-emission Transport (ULTRA) project’s primary aim was to advance the manufacture and deployment of the consortium's innovative battery cells to pre-production stage whilst utilising a UK-based supply chain.

The power-dense, Ultra-High Power (UHP), and energy-dense Ultra Energy (UE) cells promised a step change in power output, range and charge speeds that would better meet market needs and speed up the transition to low- or zero-emission vehicles.

What was Petalite’s role in the project?

Petalite’s role in this project was to progress the capability and manufacturability of EV charging infrastructure. This would support the market adoption of the consortium’s battery development efforts. Petalite envisioned a next generation DC charging solution. Built from the ground up to convert, distribute and deliver power for charging BEVs, the next-generation DC fast charging solution would address the fundamental issues of reliability, scalability and efficiency seen in existing solutions. This vision aligned with the goals of the ULTRA consortium.

Petalite’s next-generation DC fast charging solution vision hinged on the feasibility of a three-phase PowerCore. This proprietary, patented DC power supply promised high-power charging capability with the requisite reliability, scalability and efficiency due to its novel topology and current source design – known collectively as SDC technology.

Petalite had recently proven the concept of a single-phase PowerCore in the rail industry and there was a clear synergy between Petalite’s vision and the proposition being developed by the other members of the consortium.

Petalite joined the consortium and, at the end of the 3-year project, would need to be capable of charging an electric Light Goods Vehicle (eLGV) that embodied the rest of the consortium’s efforts. The charging solution had to be prototypical of Petalite’s next-generation DC fast charging solution and manufactured using processes like those which could be used for serial production.

Challenge:

Petalite had three years to build a prototype of its next-generation DC fast charging solution, capable of charging an eLGV within a few hours. This meant Petalite would need a total power supply in the region of ~120 kW.

When the project began, in May 2021, each PowerCore could output up to 5.4 kW - combining the 900 W output from each of six in-house designed single-phase transformers. That meant ~22 of the existing PowerCores would need to be paralleled. Whilst that wasn’t a technical problem – the Petalite PowerCores are uniquely stackable - there were two clear reasons why that number would need to be closer to six to appeal to industry.

Firstly, the PowerCores measure 1000 x 536 x 95 mm to slot in and out of a standard server tray for easy expansion and maintenance. These dimensions meant that the space required for only 120 kW of total power would be far too high for the market to accept. Secondly, the cost of producing each PowerCore needed to be around four times lower to be competitive on a £/kW basis.

This presented a technical challenge. Petalite needed to:

• increase the power density of the PowerCore
• reduce the cost of producing it, fourfold.

Solution:

Petalite set out to tackle this challenge by building a new, three-phase version of the PowerCore. It would have the same reliability, scalability and efficiency characteristics as the single-phase version, but capable of outputting far more power. The dimensions of the PowerCore remained the same, but the circuitry design and components used inside were revised a number of times – including our proprietary transformer.

The PowerCore was adapted from an air-cooled- to a liquid-cooled system. Not only did this increase the efficiency of the PowerCore through improved heat extraction, but it also mitigated the impact of dust on reliability. The liquid-cooled system was off-the-shelf at first, allowing the design to be iterated more readily, before being replaced by an optimised, bespoke solution.

Petalite engaged prospective manufacturing partners throughout the project, ensuring that designs and processes were optimised with serial production in mind.

Results:

In July 2024, Petalite successfully sustained a DC output of 120 kW using six PowerCores. Each of the PowerCores were able to output up to 20 kW of power and were manufactured using processes and components that were representative of the those which will be used in serial production. It now takes tens-of-minutes to manufacture each PowerCore rather than multiple hours.

The dimensions of the PowerCore, designed to fit a slot-in slot-out mounting solution, remained the same as did the cost of producing each unit. Petalite achieved the fourfold increase in power density and proportionate decrease in £/kw.

This success has been supported by new team members joining Petalite throughout the project. What began as a group of 16 employees is now 52 people strong. Our company growth is expected to reach 78 employees by June 2025.

As a result of the achievements reached throughout the ULTRA project, the technology readiness level and manufacturing readiness level of Petalite’s Power Cores has progressed from level 3 to level 6.

Reflecting on the project, APC UK's Senior Project Delivery Lead, Matt Shillito, remarked that "the progress made by Petalite as part of the APC-funded Project ULTRA has been fantastic. It has been exciting to see the company evolve its product and develop as an organisation over the course of the project, now reaching the point of having a technically cutting-edge and commercially attractive product ready to bring to market. One of the biggest obstacles to the adoption of zero-carbon vehicles has been the availability of charging infrastructure, so Petalite’s innovative design with its inherently high uptime and fast charge capability promises to help tackle this, bringing convenient vehicle charging to more locations in an affordable way."