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

instrument implementation / implementation-contract

# Battery Pack Series/Parallel Configurator implementation

A source-bound implementation contract for Battery Pack Series/Parallel Configurator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-126

**Effect**: Computation or source lookup only

## Input and validation requirements

- 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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/battery-pack-series-parallel-configurator/mechanism/>)[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`