WattCycle 48V 100Ah Rack Battery: A Closer Look at Our Latest Cycle Tests

Consistent performance matters in an energy storage system. Beyond measuring how much capacity a battery delivers in a single discharge, repeated testing helps us understand how its output changes over time.

As part of our ongoing product validation, we are sharing two internal cycle-test datasets for the WattCycle 48V 100Ah Rack Battery. These results offer an initial look at performance under a defined charging, discharging, and rest sequence.

How We Conducted the Tests

The two batteries featured in this article were selected from new, mass-produced units on our production line. Both batteries retained their default settings, including active balancing enabled, and followed the same programmed test sequence.

For a battery rated at 100Ah, a 50A current corresponds to a nominal 0.5C rate. Delivering approximately 105Ah at this current takes a little over two hours.

The values above describe the programmed test settings. The accompanying raw records show the measured voltage, current, capacity, energy, and step transitions throughout testing.

Why Include Rest Intervals?

Energy storage batteries operate under a variety of load patterns. Solar charging varies with available sunlight, household demand rises and falls, and backup systems may spend extended periods on standby before supplying power.

A cycling procedure with defined rest intervals gives us a repeatable way to evaluate performance when pauses occur between charging and discharging. In these tests, we included a 30-minute rest after the main charge and another after discharge.

Rest also helps electrochemical polarization gradually subside. During charging and discharging, ion concentration gradients and processes at the electrode interfaces cause the battery’s operating voltage to differ from its equilibrium voltage. After current stops, some of these effects diminish as internal conditions redistribute and the voltage settles.

Allowing time for this relaxation helps establish a more consistent starting point for the next test stage. This matters because measured discharge capacity depends partly on voltage behavior and when the battery reaches its cutoff conditions.

A fixed rest period does not necessarily eliminate all polarization, and these initial results do not establish whether the rest intervals extend cycle life. Longer-term testing is needed to evaluate those effects.

This is one operating profile within our testing program. Actual installations differ in charging current, discharge demand, temperature, and time spent at different states of charge. Documenting these conditions makes the results more meaningful than a capacity figure alone.

What the First Two Datasets Show

The two datasets, labeled Group 1 and Group 2, cover testing conducted from October 26 to October 28, 2026. Each contains ten completed discharge measurements.

Under this test procedure, every completed discharge in both datasets exceeded the rated 100Ah capacity. Measured capacity decreased slightly over the recorded discharges, but the first-to-tenth change remained below 1% for each battery. These results show a very limited short-term decrease in measured capacity under this operating profile, which incorporates pauses relevant to everyday customer use.

We calculate this change by subtracting the tenth discharge capacity from the first, then dividing the difference by the first discharge capacity.

Capacity in amp-hours (Ah) describes the amount of charge delivered. Energy in kilowatt-hours (kWh) also accounts for voltage during discharge, making it particularly useful when assessing the energy available to connected equipment. At the tenth discharge, the two batteries delivered approximately 5.44kWh and 5.43kWh, respectively, as measured by the test equipment.

The accompanying Excel files contain the detailed measurements, cycle summaries, operating logs, and programmed test procedures.

Download the raw test data:

● [Group 1 — Download Raw File]

● [Group 2 — Download Raw File]

Each export also includes an unfinished eleventh cycle, which is excluded from the results summarized in this article.

Expanding to 10 Batteries and 200 Cycles Each

Our ongoing testing program includes 10 randomly selected new batteries, each scheduled for 200 charge–discharge cycles, for a planned total of 2,000 cycles across the program.

This broader dataset will help us examine how capacity changes over a longer sequence and how consistent the results are across individual batteries.

The two datasets published here are an interim release. We will share additional results and their corresponding test conditions as testing progresses.

More Configuration Options Coming Soon

Alongside our testing work, we are preparing to open access to supported BMS configuration settings, giving users more flexibility to adjust available parameters for different applications. We expect to make this available soon.

We will continue evaluating default settings as part of our product development work while offering additional flexibility for users with more specific operating needs.

We also welcome customers to share their own test results with us.