Allye Energy has unveiled a major upgrade to its MAX300 battery energy storage system, positioning it as a high-power solution for fleet depot electrification without the need for costly grid upgrades.
The upgraded MAX300 can now deliver up to 400kW of DC fast charging from existing grid connections, enabling operators to expand EV charging capacity significantly faster and more affordably. The system starts at under £99,000 and is eligible for support through the UK Government’s Depot Charging Scheme, which closes to applications on 30 June 2026.
Image: Allye
Designed for both fixed and mobile use, the MAX300 combines more than 300kWh of usable energy storage with integrated DC fast charging, allowing fleets to install additional charge points and support higher-powered charging without waiting months for Distribution Network Operator (DNO) upgrades.
Jonathan Carrier, Founder and CEO at Allye Energy, said: “The Depot Charging Scheme is a real opportunity for fleet operators, but only if the technology can actually solve the grid constraint problem. The MAX300 does that, at a price point that makes the economics work, in a package that also generates revenue when it isn’t charging. We handle the full integration and we can support operators through the application. For any fleet operator who needs to electrify and hasn’t found an infrastructure solution that works yet – this is it.”
The upgraded system is based on three key engineering developments created in-house by Allye. These include the introduction of an 800V battery architecture, a redesigned lightweight chassis that reduces overall weight by 380kg, and a proprietary DC-to-DC fast charging platform built using automotive-grade components.
The 800V architecture enables higher power transfer rates while reducing energy losses, supporting ultra-rapid charging levels previously difficult to achieve in a mobile energy storage system of this size. Allye said its platform can independently manage battery packs of different voltages and chemistries within a single unit, allowing the use of second-life EV batteries from multiple supply sources.
The company has also redesigned the trailer structure to integrate the axle and towing frame directly into the load-bearing chassis. The result keeps the MAX300 below the 3.5-tonne towing threshold, meaning it can be transported using a standard driving licence.
As a fully mobile solution, the MAX300 can be deployed to construction sites, events, vehicle testing facilities and temporary charging locations. The unit can also recharge itself using public DC charging infrastructure, with a 20% to 80% recharge taking just over 40 minutes.
Robert Carter, CTO at Allye Energy, said: “A fleet operator shouldn’t have to wait months for a grid upgrade before they can charge their vehicles. The MAX300 means they don’t have to. Plug into an existing connection and you have up to 400kW of DC fast charging available immediately. Equally, you can recharge this system on-the-go from a public DC fast charger. The engineering behind that is genuinely complex – the experience for the operator is genuinely simple.
Image: Allye
“With over 300kWh of storage, it keeps going long after competing systems have run out of energy. And when it isn’t charging vehicles, that same storage capacity is earning money from grid services. It is a fundamentally different proposition from anything else on the market.”
Allye said the system is designed to tackle one of the biggest barriers facing depot electrification: limited grid capacity. By storing electricity during lower-demand periods and releasing it when needed, the MAX300 effectively increases the charging capability of existing depot connections without major infrastructure work.
In addition to powering fleets, the system can participate in grid balancing and flexibility services when not in active use, creating additional revenue opportunities for operators.
The company believes the combination of mobility, battery storage and ultra-rapid charging offers a new approach to fleet electrification, particularly for operators facing long waits and high costs associated with grid reinforcement projects.
