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Step 3 — New Battery Assignment

Purpose

The New step captures the details of the fresh replacement battery. The attendant scans, connects, and reads the new battery — then the app automatically calculates the energy difference and determines the swap cost.

Workflow

  1. Scan the QR code on the fresh (charged) battery.
  2. Connect to the battery via Bluetooth Low Energy (BLE).

  3. Read the battery's data from its BLE services:

    BLE Service Data Read Description
    ATT (Attribute) Battery ID Unique identifier of the new battery
    DTA (Data) Energy level Energy stored in the new battery (kWh)

  4. The app records the new battery ID and energy level.

Cost Calculation

Once both the old and new battery readings are available, the app calculates the swap cost automatically:

energy_difference = floor(new_energy - old_energy, 2)
net_energy        = energy_difference - quota_remaining
cost              = net_energy × rate_per_kWh
Variable Source
new_energy Read from the new battery's DTA service (this step)
old_energy Read from the old battery's DTA service (Step 2)
quota_remaining Retrieved from the backend (Step 1)
rate_per_kWh Retrieved from the backend (Step 1)

The energy difference is floored to 2 decimal places before any further calculation. If the customer's quota covers the entire energy difference, the cost is zero and payment will be skipped.

UI Behavior

  • The scan area provides clear visual guidance for QR placement.
  • Once connected via BLE, the new battery ID and energy reading are displayed.
  • The energy difference and calculated cost are shown immediately after the reading completes.
  • A summary card highlights: new energy, old energy, difference, quota applied, and amount due.

What Gets Recorded

Field Example
New battery ID BAT-2024-00789
New battery energy 2.85 kWh
Energy difference 2.47 kWh
Quota applied 0.50 kWh
Net cost CFA 394.40

Error Handling

  • QR code unreadable — retry scan or enter battery ID manually
  • BLE connection failed — ensure Bluetooth is enabled and the battery is in range; retry connection
  • Energy read timeout — the app retries automatically; if it persists, the attendant can re-scan

Actions

  • Continue proceeds to Step 4 — Review
  • Back returns to Step 2 — Return Old Battery