Battery Test System Integration Case Study – EV Pack Test Racks with Safety Interlocks
When an EV battery lab buys new battery testing equipment, the hard part often starts afterwards: turning standalone battery test systems, thermal chambers and safety devices into a reliable, documented battery test system. In this case study we walk through a representative EV battery pack test system integration project where TPS delivered fully wired test racks with safety interlocks, BMS communication and regenerative power.
You will see how we combined commercial battery test equipment from leading battery test equipment manufacturers with our own cabinet and wiring know-how to build multi-rack, multi-channel battery testing systems for high-voltage packs. We focus on integration problems that lab and test engineers actually struggle with: channel routing, safety interlocks, BMS interfaces and documentation that survives audits.
1. Who this integration case is for
This project is typical for labs that already own one or more programmable cyclers or complete battery testing systems, but need to turn them into a safe, scalable EV battery pack test system. The stakeholders were:
- Battery test engineers responsible for running life-cycle and performance tests on EV packs.
- BMS engineers validating new firmware, protection limits and communication behavior.
- Lab managers under pressure to increase throughput and meet safety requirements.
The lab had recently invested in high-power regenerative battery testing equipment capable of testing packs up to several hundred kilowatts, similar to commercial battery test solutions from Chroma and Keysight Scienlab systems where multi-channel cyclers regenerate energy back to the grid. What they lacked was a cohesive mechanical and electrical integration: cabinets, DC bus, safety circuits and BMS communication wiring that would turn loose components into a repeatable battery test system.
2. Integration challenge: from standalone cyclers to complete EV battery pack test systems
On paper the lab already owned enough battery testing equipment to run EV battery pack testing: four high-power cyclers, two climate chambers and several BMS test benches. Vendors like Keysight and Chroma emphasize that modern regenerative battery testing systems can flexibly combine cells, modules and packs and feed more than 90% of the discharged energy back to the grid. But equipment alone does not create a safe, maintainable battery test system.
The lab team had several specific integration pain points:
- Each cycler shipped as a separate battery test equipment rack with only basic cabling.
- No common DC bus, so every new pack required new cables routed across the lab.
- Safety relays and safety interlock switches were wired differently at each station.
- BMS communication harnesses were point-to-point, making it hard to debug BMS communication faults.
- Documentation for existing setups was incomplete, complicating battery management system testing and audits.
They asked TPS to turn this into a modular battery pack test system: a set of integrated battery testing systems where cyclers, chambers and packs could be reconfigured without rewiring the entire lab and where safety interlocks, BMS connections and documentation were consistent.
3. Solution overview – three integrated battery test racks
TPS proposed a three-rack layout for the integrated battery testing system:
- Rack A – Power and cyclers. High-power regenerative cyclers forming the heart of the battery cycler system, AC distribution and main safety contactors.
- Rack B – Safety and control. Safety PLC, relays, emergency stop loop and hardwired safety interlock circuits, plus I/O for chamber and coolant controls.
- Rack C – BMS and pack interfaces. Patch panels for DC, BMS communication and pack fixture connections, acting as the main interface for EV battery test equipment.
This architecture followed many of the principles from our public battery test system power & safety architecture guide, but here it was implemented for a concrete EV battery testing system with fixed hardware, short cable runs and a documented safety chain.
4. BMS communication and battery management system testing support
One of the goals of the project was to make battery management system testing easier. Many vendors now recommend using emulators and dedicated BMS test stands so engineers can verify protection functions, state estimation and communication behavior safely. The lab already had BMS benches, but the wiring between the benches, packs and the new battery testing systems was ad-hoc.
TPS added a structured BMS interface in Rack C:
- Front-panel connectors for pack-side CAN and Ethernet, plus separate connectors for lab BMS benches.
- Shielded cables routed through dedicated ducts, isolated from high-current DC paths.
- Test points and LEDs that made it easier to diagnose BMS communication faults.
- Pre-defined pin-outs documented in the same wiring diagrams as the power system.
This meant that when engineers switched from one EV pack design to another, they could keep using the same lithium ion battery testing equipment and BMS tools, just by swapping fixtures and cables at the interface rack rather than rewiring each battery test system individually.
5. Safety interlock strategy and emergency stop loop
For high-power EV battery pack testing, safety is as important as accuracy. Vendors such as Keysight include dedicated safety enclosures and PLC-based guards in their EV battery test equipment precisely because miswired packs or stuck contactors can cause serious damage.
TPS implemented a layered safety concept in this integrated battery testing system:
- A global emergency stop loop using redundant safety interlock switches on doors and pack fixtures, controlled by a safety PLC in Rack B.
- Hardwired interlocks from the safety PLC to each cycler’s enable input, plus main contactors in the power rack.
- Local E-stop buttons at operator stations and pack fixtures wired into the same loop.
- Safety I/O reserved for future leak detection and coolant monitoring options.
This design mirrors practices used in dedicated BMS and pack safety test systems, where a safety PLC supervises interlocks and can shut down all sources. By centralizing the logic, the customer can add more fixtures or chambers later without redesigning each battery testing system from scratch.
6. Integration workflow and deliverables
TPS followed a structured integration workflow familiar from other automation projects:
- Requirements & risk review. We mapped electrical limits, pack configurations and safety requirements, using standards and best practices similar to those discussed in BMS testing guides.
- Wiring and interlock design. DC paths, signal harnesses and safety interlock circuits were captured in schematics and safety diagrams.
- Rack build & factory testing. Racks A–C were built, wired and tested using dummy loads before any real EV packs were connected.
- On-site integration. Cyclers, chambers and fixtures were tied into the new racks, then the complete battery test systems were checked with safe, low-voltage packs.
- Documentation handover. The customer received wiring diagrams, interlock logic descriptions and checklists consistent with their internal procedures and our own battery charger EMC & safety testing workflows.
Because TPS also offers regenerative power solutions for formation and grading, we could align the cabling and protection concepts here with practices from our regenerative power supply for lithium battery formation projects.
7. Results: higher throughput, lower integration risk
After commissioning, the integrated battery testing systems delivered several concrete benefits:
- Higher utilization. Cycler channels could be reassigned between pack programs without rewiring, so the lab could run more tests in parallel on the same battery test equipment.
- Simpler changeovers. New pack fixtures only required changes at the interface rack, not in every battery testing system.
- Consistent safety behavior. Any safety interlock switch fault or E-stop reliably removed energy from all packs on that system.
- Audit-ready documentation. Test racks, EV battery pack test system wiring and battery management system testing interfaces were all covered in a single set of drawings and checklists.
Most importantly, the lab team no longer had to act as integration engineers on top of their normal testing work. TPS handled the cabinet, wiring, safety interlocks and documentation, so the customer could focus on developing better EV packs and BMS software.
FAQ – Battery Test System Integration
1. What is included in a TPS battery test system integration project?
A TPS integration project typically covers cabinet design, AC and DC power distribution, channel routing, safety interlock circuits, BMS communication wiring and documentation for one or more battery test systems. We start from your existing battery testing equipment and fixtures and deliver test racks that are wired, labeled and ready to connect to real packs and chambers.
2. Do you supply battery test equipment or work with existing suppliers?
In many projects the customer already owns cyclers or complete battery testing systems from established battery test equipment manufacturers. TPS focuses on integrating that battery test equipment into safe, modular racks with standardized interfaces. In other cases we collaborate with equipment vendors to specify and supply new battery testing equipment as part of a turnkey solution.
3. Can this approach be used for cell and module testing, or only EV packs?
The same integration concepts apply to cell and module lines. Multi-channel cell cyclers, module test fixtures and battery testing systems still benefit from structured DC routing, BMS interfaces and safety interlocks. For EV packs the power levels and hazards are higher, so safety PLCs and emergency stop loops become even more important.
4. How does TPS handle battery management system testing?
We design the wiring so that BMS benches and HIL systems can connect cleanly to packs and to the battery test system. That includes shielded communication cables, break-out panels and documented pin-outs. The actual battery management system testing procedures are defined by your engineering team, but our integration work makes it easier to connect instruments, inject faults and observe BMS behavior.
5. What if our lab already has some safety interlocks wired?
We can reuse existing safety interlock switches, door contacts and E-stop buttons where it makes sense. During the design phase we map your current wiring and then either integrate it into a unified safety PLC concept or replace it where necessary. The result is a consistent safety strategy across all battery testing systems instead of a mix of different schemes at each station.