Problem / Motivation

With 15-minute electricity price intervals, non-continuous charging can become highly fragmented, resulting in:

• Frequent start/stop cycles (e.g., 8 individual 15-minute sessions for 2 hours of charging)
• Increased wear on charger hardware and EV battery
• Reduced charging efficiency for EVs that perform better with longer sessions

Example: Without grouping, charging might occur at: 02:00-02:15, 02:45-03:00, 03:30-03:45, etc. → 8 start/stop cycles

Proposed Solution

Add a new Minimum Session Duration parameter:

• Range: 0-4 hours (step: 0.25h)
• Default: 0 (backward compatible)
• Type: Number entity
• Applies to: Non-continuous charging only

How It Works

When set > 0 (e.g., 1.0 hour):

1. Selects cheapest quarters as usual
2. Groups into contiguous sessions
3. Filters out sessions shorter than minimum
4. Replaces with adjacent quarters to extend existing sessions
5. Result: Fewer, longer sessions

Example with 1-hour minimum:

• Before: 8× 15-min sessions → 8 cycles
• After: 2× 1-hour sessions → 2 cycles ✅

Implementation

Files Modified

• const.py - Add constants and defaults
• __init__.py - Schema migration v7→v8
• number.py - New number entity
• coordinator.py - Parameter handling
• helpers/coordinator.py - Grouping algorithm (new _apply_minimum_session_duration())
• All translation files (en, da, nb, nl, sv)
• README.md - Documentation

Algorithm

def _apply_minimum_session_duration(selected_quarters, sorted_index, ...):
    1. Group quarters into contiguous sessions
    2. Remove sessions < minimum duration
    3. Add replacement quarters adjacent to existing sessions
    4. Iterate until all sessions meet minimum
    5. Maintain total charging time

Benefits

✅ Reduces hardware wear
✅ Improves efficiency
✅ User-configurable
✅ Backward compatible
✅ Multi-language support

User Experience

Navigate to device → Adjust "Minimum session duration" slider (0-4h)

Recommended: Start with 1.0 hour for optimal balance