Introduction
A battery can pass every voltage check in the lab and still fail the moment a customer turns the key on
a cold morning. That’s the gap high rate discharge (HRD) testing is built to close. While a standard
capacity test tells you how much energy a battery can store, an HRD test asks a different question
entirely: can this battery deliver a massive burst of current, instantly, without its voltage collapsing?
For automotive and industrial lead-acid batteries, that’s exactly the moment of truth that matters in the
real world.
At CMWTEC, HRD testing runs directly after formation, in the finishing area of the production line,
often as part of a combined test sequence alongside high voltage leakage checks. With integrated E-
Load modules rated from 500A up to 3,000A, our HRD test units can process up to 8 batteries per
minute (higher capacity on request possible), giving manufacturers a fast, reliable way to catch
batteries that fail under real load before they leave the plant. In this article, we’ll break down what an
HRD tester actually needs to get right, and the six specs that separate a production-ready HRD tester
from a lab instrument that can’t keep up with your line.
This is where AGM vacuum filling and EOL testing stop being two separate process steps and start being two halves of the same quality argument. One determines whether the cell can perform; the other confirms whether it does. Understanding how they connect — and where the industry’s biggest efficiency gains are hiding — matters for anyone specifying or upgrading a battery finishing line.
What Is High Rate Discharge (HRD) Testing?
High rate discharge (HRD) testing is a quality control method that discharges a battery at a very
high current for a few seconds to check whether it can deliver power under real load, not how much
total energy it can store.
This is the key distinction from a standard capacity test. A capacity test discharges a battery slowly,
over several hours, to measure total amp-hours delivered. An HRD test does the opposite: it applies a
short, powerful burst of current, using CMWTEC’s integrated E-Load modules, anywhere from 100A up to 3,000A, and measures how the voltage responds. If the voltage holds up, the battery
passes. If it collapses, something inside the battery (a weak weld, an internal short, incomplete
formation) isn’t right.
During the test, CMWTEC’s HRD units typically run a combination of measurements: OCV (open
circuit voltage, the resting voltage before the load is applied), CCV (closed circuit voltage, the voltage
under load), and deltaV (how deep the voltage drops during the test).
Together, these three values give a much clearer picture of battery health than a single voltage reading
ever could.
Spec #1: Test Time per Battery
The single biggest factor that determines whether an HRD tester fits into your production line is test
time. A tester that takes too long per unit becomes the bottleneck of the whole line, no matter how fast
everything else runs.
CMWTEC’s HRD units are built to keep pace with high volume automotive and industrial battery
production. Depending on the exact test profile, our machines handle up to 8 batteries per minute.
That throughput comes from the combination of a flat top chain conveyor (which positions each
battery exactly, without manual adjustment) and pneumatically driven test clamps that grip both
terminals in one smooth motion.
Spec #2: Discharge Current Range
Not every battery needs the same test current, and that’s exactly where a lot of testers fall short. A small motorcycle battery and a heavy truck battery draw very different amounts of current when they start an engine, so your HRD tester needs enough range to test both accurately.
CMWTEC covers this with the CHL-500 E-Load module line, scalable from 500A up to 3,000A. This range matters for two reasons. First, it means one tester family can cover automotive, motorcycle, and heavier industrial lead-acid batteries without swapping equipment. Second, testing at the wrong current range gives misleading results: too low, and a weak battery might still pass; too high, and you risk damaging a battery that would otherwise have been fine.
Spec #3: Data Logging & Traceability
A pass or fail result alone isn’t enough anymore. If a customer disputes a quality issue months later, or if you need to trace a batch of defective batteries back to a specific production window, you need a full data trail, not just a green light on a screen.
CMWTEC addresses this on two levels. On combination machines (2-in-1 through 5-in-1), an optional 2D scanner captures the battery code data during testing, linking each result directly to an individual unit. Test data can also be read out via an interface for further analysis, and on the 4-in-1 line, statistical evaluation with a visual display lets operators spot trends across a production run, not just single test results.
Spec #4: Line Integration
An HRD tester rarely runs alone. In most production setups, it needs to work alongside other finishing steps like post brushing, high voltage leakage testing, greasing, or date code marking, without becoming its own isolated island of equipment.
CMWTEC’s HRD test units are built as modular function units that share one main frame, one PLC controller, and one HMI touch panel, whether they’re running standalone or as part of a combined line. That means a manufacturer can start with just HRD testing and later add brushing, HVT, greasing, or needle marking (up to a 5-in-1 configuration) without replacing the core testing unit. Change-over between battery types is designed to be quick, and on the 4-in-1 line, automatic test sequences can run up to 5 different test profiles.
Spec #5: OCV Pre-Check & Pass/Fail Logic
A good HRD tester doesn’t just apply a high current and hope for the best. It should check the battery’s baseline condition first, then run the load test, then make a clear, automatic decision, all without an operator having to interpret raw voltage curves by hand.
CMWTEC’s process follows exactly this sequence. Before the high current load is applied, the system captures OCV (open circuit voltage) as a baseline. During the test, it monitors the performance under load, after the test, it measures CCV (closed circuit voltage) and calculates deltaV, . CMWTEC’s EOL Control Software evaluates these values automatically and, if a battery fails, the reject unit ejects it onto a separate table at the end of the machine, with the failure shown directly on the touch panel.
Spec #6: Build Quality & Made-in-Germany Precision
An HRD tester runs in a production environment, not a lab. That means constant vibration, dust, temperature swings, and years of near-continuous operation. If the build quality isn’t there, even the best measurement technology won’t hold up.
CMWTEC’s HRD test units are built primarily from stainless steel (316L or 316Ti, depending on the model), which resists corrosion and wear far better than standard steel over years of operation. Power consumption ranges from roughly 3.5 kW for a standalone HRD unit up to 11 kW for a full 4-in-1 combination line, and all machines run on standard 230/400V three-phase industrial power. Every unit is engineered and manufactured in Germany.
Conclusion & Next Steps
Choosing the right HRD tester comes down to six things: test time, discharge current range, data logging, line integration, measurement logic, and build quality. Get those right, and you catch weak batteries before they ever leave your plant, instead of dealing with warranty claims months later.
CMWTEC’s HRD test units cover this full range, from a single standalone tester up to a fully integrated 5-in-1 line combining brushing, HRD testing, high voltage leakage testing, greasing, and needle marking, all built in Germany with up to 3,000A of discharge current and throughput of up to 8 batteries per minute.
If you’d like to know which configuration fits your production line, get in touch, we’re happy to advise on the right HRD solution.