EV Charge Time & Cost Calculator implementation

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

t4-163

Effect

Computation or source lookup only

Input and validation requirements

The calculator has a definite undefined-result break when charger_kw is zero. It also needs validation for target_percent below start_percent and an explicit charge-efficiency input convention; otherwise it can return negative or physically nonsensical results.

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": {
    "battery_kwh": 60,
    "start_percent": 20,
    "target_percent": 80,
    "charger_kw": 11,
    "rate_per_kwh": 0.3,
    "charge_efficiency": 0.9
  },
  "expected_outputs": {
    "energy_added_kwh": 36,
    "energy_kwh": 40,
    "time_hr": 3.6363636364,
    "cost": 12
  },
  "working": "Battery energy added = 60 × (80 − 20) / 100 = 60 × 0.60 = 36 kWh. Grid energy = 36 / 0.90 = 40 kWh. Time = 40 / 11 = 3.6363636364 hr. Cost = 40 × 0.30 = 12.00 currency units."
}

Other records

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