In a previous post, we introduced Electric Era's multi-layered approach to quality, highlighting how processes like Qualification Test Procedures (QTP) are fundamental to building reliable products. Reliability doesn't happen by accident; it's proven through meticulous testing. Now, let's take a closer look at one of the most critical aspects of our QTP: validating performance in harsh environmental temperatures.
Ensuring our Battery Energy Storage System (BESS) operates flawlessly, whether in the peak of summer or the dead of winter, is paramount. To support our rapidly growing fleet and ensure best-in-class reliability in any climate, we conducted an exhaustive thermal qualification campaign.
Simulating the Extremes: The Test Setup
To truly understand our system's limits, we couldn't just rely on vendor component specifications. We needed to test the entire assembly as it operates in the field. To do this, we placed our Qualification Test Unit inside a 4'x4’x6' thermal chamber.
Our goal was to simulate real-world conditions as accurately as possible. This involved:
- Applying Loads: We used external DC power supplies to simulate the high-current loads of charging.
- Simulating Sunshine: Heaters were placed inside the enclosures to replicate the added thermal load from direct sun exposure.
- Meticulous Monitoring: We attached 17 Resistance Temperature Detectors (RTDs) to critical components—like the main contactor, precharge resistor, and the site controller CPU—to collect detailed temperature data throughout the tests.
From Low to High Temperatures: The Tests
We subjected the system to a series of demanding tests. The primary test cycles ran at the Nexus system's nameplate operating temperatures of +45°C (113°F) and -25°C (-13°F).
But we didn't stop there. To find potential weaknesses early, we pushed the design to its absolute limits with an extreme test series at +60°C (140°F) and -40°C (-40°F), going well beyond the specified operating range. These tests included steady-state operation, transient pre-charge cycles, and, most importantly, cold-start boot-ups after being "soaked" at freezing temperatures overnight.
Key Takeaways: From Data to Design Upgrades
This rigorous testing is not about a simple pass/fail grade; it’s about gaining a deep, root-level understanding of our system to make it better. While the system performed well in the high-temperature tests, the real value came from the opportunities for improvement we discovered.
- Improving the Cold Start: The tests revealed issues with telemetry during cold starts at -25°C and below. Identifying this in a controlled lab environment is exactly why we test—it allows us to engineer a solution before it can impact a customer site. We're now actively working with our component supplier to resolve these cold boot issues.
- Enhancing Thermal Management: At low temperatures, we saw a significant 20°C temperature gradient across the electrical enclosure. Our data showed the existing heater couldn't distribute heat evenly in the absence of airflow. This led to a key design change recommendation: upsizing the heater and, crucially, adding an internal fan to equalize the ambient temperature.
- Verifying Every Detail: Our initial test plan missed directly monitoring the high-current cables. In the spirit of thoroughness, we ran a follow-up test specifically to characterize the temperature of these cables. The results gave us confidence that even under a heavy load, the cable temperature remains safely below that of the main contactor, which was the hottest recorded component.
These findings have already been translated into action. Design upgrades, including active internal temperature monitoring and active control of the fan and heater, are already in progress.
Conclusion: Building Trust Through Testing
This deep dive into thermal qualification is a clear example of our commitment to quality in action. By pushing our systems to their breaking point, we uncover valuable insights that allow us to refine and strengthen our designs. This multi-layered validation process—from receiving inspection to full-system QTP and final site commissioning—is how we build robust, reliable products. It’s how we ensure that every Electric Era charging station delivers unwavering performance and safety, building not just chargers, but trust.