What happens when 100,000 chargers connect at once?

As EV charging networks grow, one question becomes unavoidable: can the software behind them actually keep up?

For operators, growth brings opportunity. More chargers, more sessions, more users. But it also brings pressure. A platform that performs well with a few thousand charging stations can behave very differently when that number rises, or when thousands of devices connect, send data, or request authorization at the same time.

That is why scalability in EV charging cannot be assumed. It has to be tested, measured, and proven.

At ihomer, we are leading the way in this area. Our Infuse team is building a CPMS testing environment that simulates real charging stations and real behaviour at a significant rate, scaling up to 100,000+ stations. This helps validate how the platform performs under pressure and gives customers the confidence to grow.

Why scalability is a real risk

In many cases, platforms appear stable until they are pushed to their limits.

When that happens, problems can surface quickly. Systems slow down. CPU and memory usage increase. Processes begin to fail. In the worst case, the platform can go down entirely.

The consequences are immediate and practical. Charging sessions may be interrupted. New users may not be able to start charging. Meter values may not be processed correctly, which directly impacts billing and revenue. In some cases, drivers may even be able to charge for free if data is lost.

This is why scalability is not just a technical concern. It is a reliability issue, a customer experience issue, and a business risk.

From working system to scalable platform

This isn’t theoretical work. It is built on deep experience in software architecture and years of delivering Infuse solutions for demanding customers.

Our backend expert Ed Bras, with over 26 years of experience (including extensive Java expertise and time in startups and financial systems), has been leading the development of ihomer’s large-scale CPMS simulation environment. He has seen firsthand where systems succeed, and where they begin to fail under real growth.

“If you're not ready to scale, the platform is going to get really slow. CPU and memory usage go up, and the system can easily fall over,” explains Ed.

This is exactly why large-scale testing matters. Operators need to understand how platforms behave before growth exposes weaknesses in production environments.

“If you're not able to process those meter values, you have no idea how much someone charged. That means you’re losing money.”

This is why scalability cannot be treated as a future problem. As Ed puts it: “There’s only one way to answer that. You have to test it.”

From assumption to proof

As EV infrastructure expands, operators, especially in large tenders, are increasingly asked to show their platforms can handle real demand at volume.

ihomer stands out here because we don’t rely on assumptions. We prove performance under real-world conditions and deliver data-backed evidence of how Infuse CPMS behaves under load.

At the core of our testing environment is high-fidelity simulation using k6, an open-source load-testing tool.

We populate a realistic CPMS setup with tens of thousands of simulated charging stations and generate authentic OCPP traffic over WebSockets. We also run different test types: load, soak, stress, and peak “thundering herd” scenarios.

The simulated chargers are indistinguishable from real ones to the CPMS. We start with single-instance testing (currently pushing toward 50,000 stations under moderate load) and are moving to multi-instance setups with intelligent load distribution to support 100,000+ stations.

We also test the broader Infuse ecosystem, including our IAM system and OCPI broker, to validate end-to-end behaviour.

Making system behaviour visible

Testing at high demand levels only becomes valuable if the results are clear and actionable.

To achieve this, the team combines simulation with observability tools such as OpenTelemetry and Dash0, to monitor system behaviour under load. This helps identify bottlenecks, track performance over time, and uncover issues before they affect real-world operations.

Building for reliability at scale

At its core, this work is about more than performance. It is about reliability.

As charging networks grow, operators can no longer rely on simple fixes like restarting systems during issues. Even short downtime can have a significant impact on operations and revenue.

This is why we follow reactive principles when designing and testing systems. That means building platforms that are resilient, fault tolerant, and able to handle increasing demand.

It also means preparing for multi-instance architectures, where load is distributed across multiple systems. This ensures that if one part of the system needs to be updated or fails, the rest can continue operating without disruption.

A shift in industry expectations

What makes this work particularly relevant is that this level of testing is still relatively new in the EV charging industry.

While performance testing is common in other sectors, applying it at this scale and with EV-specific scenarios is still emerging. Yet as networks grow, it is becoming essential.

Operators and enterprise customers are asking more detailed questions. They want proof of performance, not just promises. They want to understand how systems behave under pressure before committing to them.

This is where operators turn uncertainty into proven performance. Not by claiming scalability, but by proving it.

The future of eMobility

The next phase of eMobility will be defined by growth and complexity. Larger networks, more complex systems, and higher expectations.

In that environment, platforms will need to demonstrate that they can handle real-world conditions reliably.

By building a large-scale CPMS testing environment, our team is helping move the industry in that direction. It is turning uncertainty into measurable insight and giving operators the confidence they need to grow.

Because in EV charging, scalability is not a promise. It is something that must be proven.

Ready to test your platform?

At ihomer, this testing environment is not limited to our own platforms. We can also simulate and validate charging infrastructure independently from the underlying CPMS, helping operators and technology providers understand how their systems behave under real-world pressure.

If you want to explore how your platform performs under high demand, large-scale charging scenarios, or complex network conditions, let’s talk about how we can help: ihomer.nl/en/over-ons/contact.