An EC Labor measurement guide with manufacturer references and our own calculated example.
Beyond cycling
A battery cycler records the cell response during controlled charging and discharging steps. Current, voltage and time measurements can be used to calculate charge and energy; repeated cycles reveal changes in performance.
Which configuration do you need?
In addition to the cell’s current and voltage requirements, the number of experiments that must run in parallel is important. Independent measurement channels are particularly valuable for long ageing studies.
Resolution, accuracy and repeatability are different properties. EIS capability and analysis software also influence which research questions the system can address. The BioLogic guide brings these selection criteria together. BioLogic: battery cycler operation and selection.
Capacity and energy: different results from the same data
Our teaching example discharges a cell at a constant 0.500 A for 3.60 hours, ending at the lower voltage limit selected for the experiment. Total discharged charge is Q = I × t = 0.500 × 3.60 = 1.800 Ah. This is capacity under the stated protocol, not a cell constant valid under every condition.
Suppose the time-averaged voltage during discharge is 3.60 V. Since current is constant, energy is W = I × Ū × t = 6.480 Wh. Using the label’s nominal voltage, assumed here to be 3.70 V, would instead give 6.660 Wh: 0.180 Wh or about 2.78% more. With changing current, generally integrate U(t) × I(t) over time; multiplying average voltage by average current is insufficient.
Let the preceding charge step supply 1.840 Ah and 7.020 Wh. This cycle’s coulombic efficiency is 1.800 / 1.840 = 97.83%, while energy efficiency is 6.480 / 7.020 = 92.31%. These invented illustrative values are not performance data for a BioLogic instrument or a battery chemistry.
The ratios require consistent definitions of charge and discharge boundaries. Make conditioning, rest periods and excluded steps traceable. One favourable efficiency value does not establish long life or high-power capability.
File size is not measurement information
In another original example, a 100 ms pulse at 2 A transfers 0.200 C = 0.05556 mAh. If an export contains one instantaneous sample each second, the entire pulse could fall between samples. Post-processing that export might return zero charge even though charge flowed.
This is not a claim that a particular instrument loses data. Before purchasing, establish the internal time step used for charge and energy calculations, what the file stores and what an export includes. Raw data resolving pulse edges and integrated quantities answer different questions. BioLogic: recorded data and calculated quantities. BioLogic: calculated and recorded data.
Our suggested acceptance check runs a known protocol with two recording settings. Compare step boundaries, integrated charge and values recalculated from exports. Document discrepancies; do not automatically consider the larger file more accurate.
Maximum current is only one selection criterion
The BCS-1012 specification lists 32 channels per module, a 0–5 V range and up to ±6 A per channel, without built-in EIS. It can be a starting point for multi-cell ageing when the protocol fits these limits. BioLogic BCS-1012 specification.
BCS-905/910/915 models cover different current ranges, with optional EIS available. Negative-voltage /n versions must be distinguished from standard models. BioLogic BCS-900 series.
Our requirement example calls for 24 independent channels for 24 cells. If a supported configuration combines several physical channels to deliver higher current to one cell, those channels cannot simultaneously test separate cells. Specify the resulting number of independent experiments in the quotation.
Turn the protocol into acceptance checks
Our proposed list translates a research plan into verifiable technical questions:
- Complete protocol: minimum and maximum current, full cell-voltage window, pulse length, rests and termination criteria.
- Small signals: range, accuracy equation and noise at the lowest current of interest; displayed digits alone are insufficient.
- Parallel work: independent channel count, shared resources and EIS scheduling.
- Long runs: test interruption of the network connection and document data retention and continuation behaviour.
- Stopping: verify the limits required for the actual cell, temperature measurement and reactions to signal faults using the manufacturer procedure.
Keep a short raw dataset and exact software version with the results. This helps distinguish later changes in the measurement procedure from cell ageing. For a months-long study, record who owns the protocol and how changes are approved within the laboratory; otherwise nominally identical cycle numbers may hide different experimental histories.
The battery internal-resistance guide explains why DC and AC results differ. Narrow candidates with the instrument finder, then discuss the complete protocol to establish the configuration.