Source: https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/mechanism/

instrument mechanism / verified-clean

# Battery Pack Series/Parallel Configurator mechanism

The inspectable method record for Battery Pack Series/Parallel Configurator, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The core series/parallel arithmetic is standard and correct under the stated ideal assumptions. The specification needs an explicit voltage convention (nominal, maximum, or operating range), explicit validation constraints for S and P, and either removal of the optional weight output or a defined weight formula and required inputs.

- Vpack=S·Vcell, Cpack=P·Ccell, and Wh=Vpack·Cpack are correct for identical cells in an ideal SxP arrangement.

- The formulas do not account for voltage sag, usable-depth-of-discharge limits, charge/discharge efficiency, cell mismatch, wiring losses, or BMS limits; outputs are therefore nominal/theoretical values.

- The listed optional weight estimate has no formula, cell-mass input, enclosure-mass input, or definition of whether it is an estimate or a measured result.

## Units and conventions

- Vcell is in volts (V), Ccell is in ampere-hours (Ah), and Wh is watt-hours.

- Vcell and Ccell are nominal cell ratings; Wh is nominal stored energy, not guaranteed usable energy.

- S and P are positive integer counts: S is the number of cells in series and P is the number of parallel strings.

- Cells in every series and parallel position are assumed identical and connected in a conventional SxP topology.

- If capacity is supplied in mAh, it must be divided by 1000 before applying Cpack=P·Ccell; for example, 2500 mAh=2.5 Ah.

- The spec does not explicitly state nominal versus maximum/minimum cell voltage, so the voltage interpretation is ambiguous.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "cell_voltage_V": 3.7,
    "cell_capacity_Ah": 2.5,
    "S": 3,
    "P": 4
  },
  "expected_outputs": {
    "pack_voltage_V": 11.1,
    "pack_capacity_Ah": 10,
    "pack_energy_Wh": 111
  },
  "working": "Vpack=S·Vcell=3·3.7=11.1 V. Cpack=P·Ccell=4·2.5=10 Ah. Wh=Vpack·Cpack=11.1·10=111 Wh."
}
````

## Failure boundary

- Reject S<=0 or P<=0; zero or negative counts are physically invalid and can produce zero or nonsensical pack ratings.

- Require S and P to be integers; fractional cell counts are invalid.

- Reject missing, nonnumeric, zero, or negative cell voltage and capacity inputs.

- Avoid division by zero in any future reverse-calculation feature when deriving S, P, or cell values.

- Prevent accidental mixing of mAh and Ah; silently treating 2500 mAh as 2500 Ah creates a 1000-fold capacity and energy error.

- A pack's actual usable energy is lower or different than nominal Wh depending on cutoff voltage, load, temperature, aging, and efficiency.

- A weight output without a defined model must not be presented as an authoritative result.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`