Why sequential high-power charging outperforms balanced distribution for InCharge Energy deployments
Fleet operators choosing InCharge Energy solutions face a common scenario: maximizing overnight charging efficiency when power constraints force difficult allocation decisions. Consider a typical depot deployment — 10 InCharge Energy 60kW units or 10 InCharge Energy 30kW DC chargers with dual-connector capability, a 150kW site electrical service, and 20 fleet vehicles with 90kWh batteries requiring overnight charging. The critical question: Should the InControl platform distribute 7.5kW to all 20 vehicles simultaneously, or prioritize sequential high-power charging?
The answer challenges conventional thinking about "fair" power distribution and reveals why InCharge Energy's intelligent power management delivers superior fleet readiness outcomes.
The Fleet Charging Challenge
Deployment Scenario
- Infrastructure: 10 InCharge Energy 60kW DC chargers (dual-connector, supports parallel (simultaneous) charging)
- Site Constraint: 150kW electrical service
- Fleet: 20 vehicles, 90kWh battery capacity each
- Charging Window: 8-hour overnight period
- Target: Maximum fleet energy replenishment
Power Allocation Options
Option A: Balanced Distribution
- 150kW ÷ 20 vehicles = 7.5kW per vehicle
- All vehicles charge simultaneously at heavily reduced power
- Utilizes ICE-60s (60kW machines) that support parallel charting, all InCharge Energy connectors immediately providing power to vehicles
Option B: Sequential High-Power Charging
- 10x 30kW dual connector InCharge Energy chargers that support sequential (first one fills the battery, then the other) charging
- 10 vehicles charge at 15kW each (150kW ÷ 10 active chargers)
- Sequential rotation through remaining 10 vehicles
- Each InCharge Energy charger operates closer to optimal efficiency
Option C: Optimized Sequential
- 5 vehicles charge at 30kW each (maximum charger capability)
- 4 charging cycles over 8-hour period
- Each InCharge Energy charger operates at rated efficiency
InCharge Energy Charger Efficiency Analysis
DC Fast Charger Loss Profile
Let's assume some typical power conversion characteristics from the heavy duty vehicle and charger combined:
Fixed Overhead Components:
- Power factor correction: ~0.8kW
- Cooling systems: ~1.2kW
- Control systems and networking: ~0.5kW
- Standby and auxiliary loads: ~0.3kW
- Total fixed overhead: ~2.8kW per active charger
Variable Conversion Losses:
- Power electronics efficiency: ~4% of delivered power
- Cable and connection losses: ~1% of delivered power
Efficiency Comparison by Power Level
7.5kW Charging (Option A):
Per vehicle analysis:
- Delivered power: 7.5kW
- Variable losses: 0.4kW (5% of 7.5kW)
- Fixed overhead: 2.8kW
- Total input power: 10.7kW
- Charger efficiency: 70%
Total site:
- 20 vehicles × 10.7kW = 214kW required
- Exceeds 150kW site capacity
- Not technically feasible
15kW Charging (Option B):
Per active charger:
- Delivered power: 15kW
- Variable losses: 0.8kW (5% of 15kW)
- Fixed overhead: 2.8kW
- Total input power: 18.6kW
- Charger efficiency: 81%
Total site:
- 10 chargers × 18.6kW = 186kW required
- Exceeds 150kW site capacity
- Requires power management
30kW Charging (Option C):
Per active charger:
- Delivered power: 30kW
- Variable losses: 1.5kW (5% of 30kW)
- Fixed overhead: 2.8kW
- Total input power: 34.3kW
- Charger efficiency: 87%
Total site:
- 5 chargers × 34.3kW = 171.5kW required
- Exceeds capacity but manageable
- 4-5 chargers maximum simultaneously
Fleet Energy Delivery Analysis
Realistic Power Management Scenario
Given the 150kW constraint, let's model feasible approaches:
Modified Option A: Reduced Balanced Distribution
- 13 vehicles charging at 7.5kW (efficiency: 70%)
- 7 vehicles queued
- Total delivered: 97.5kW to batteries
- Site efficiency: 65%
Modified Option B: Sequential 15kW
- 8 vehicles charging at 15kW (efficiency: 81%)
- 12 vehicles queued
- Total delivered: 120kW to batteries
- Site efficiency: 80%
Modified Option C: Sequential 30kW
- 4 vehicles charging at 30kW (efficiency: 87%)
- 16 vehicles queued
- Total delivered: 120kW to batteries
- Site efficiency: 80%
8-Hour Overnight Analysis
Balanced Distribution (7.5kW):
Energy per vehicle: 7.5kW × 8 hours = 60kWh
Fleet coverage: Can charge 13 vehicles to 60kWh
Remaining vehicles: 7 vehicles uncharged
Total fleet energy: 780kWh
Average fleet charge: 43% (780kWh ÷ 1800kWh total capacity)
Sequential 15kW:
Charging cycles: 8 hours ÷ 4 hours per cycle = 2 cycles
Vehicles per cycle: 8 vehicles
Energy per vehicle: 15kW × 4 hours = 60kWh
Total vehicles charged: 16 vehicles to 60kWh
Remaining vehicles: 4 vehicles uncharged
Total fleet energy: 960kWh
Average fleet charge: 53%
Sequential 30kW:
Charging cycles: 8 hours ÷ 2 hours per cycle = 4 cycles
Vehicles per cycle: 4 vehicles
Energy per vehicle: 30kW × 2 hours = 60kWh
Total vehicles charged: 16 vehicles to 60kWh
Remaining vehicles: 4 vehicles uncharged
Total fleet energy: 960kWh
Average fleet charge: 53%
The InControl Platform Advantage
Dynamic Power Management
InCharge Energy's InControl platform can implement sophisticated power management beyond simple sequential charging:
Adaptive Sequential Charging:
- Monitor actual vehicle power acceptance
- Dynamically redistribute unused power allocation
- Optimize for charging curve efficiency (high power at low SOC)
- Integrate with fleet telematics for departure time optimization
Real-World Optimization Example:
Hour 1-2: 4 vehicles at 30kW (low SOC, high acceptance)
Hour 3-4: 5 vehicles at 24kW (moderate SOC, reduced acceptance)
Hour 5-6: 6 vehicles at 20kW (higher SOC, further reduced acceptance)
Hour 7-8: 8 vehicles at 15kW (completing charge cycles)
This dynamic approach could deliver 1,080kWh total fleet energy (60% average charge) compared to 780kWh with balanced distribution.
Fleet Management Integration
InControl's API enables fleet-specific optimizations:
Route-Based Prioritization:
- Vehicles with longer next-day routes charge first
- Integration with fleet management systems for route planning
- Departure time optimization for operational efficiency
Battery Health Considerations:
- Avoid consistently low-power charging for battery longevity
- Implement charging curves optimized for fleet vehicle chemistry
- Monitor and adapt to individual vehicle degradation patterns
Implementation Strategy for Fleet Operators
Phase 1: Baseline Sequential Charging
- Implement 4-vehicle cycles at maximum charger power
- Establish baseline efficiency and fleet readiness metrics
- Monitor actual vs. theoretical energy delivery
Phase 2: Dynamic Power Management
- Deploy InControl's advanced power allocation algorithms
- Integrate with existing fleet management systems
- Optimize based on historical charging patterns and route requirements
Phase 3: Predictive Optimization
- Leverage vehicle telematics for predictive charging needs
- Implement machine learning for optimal power allocation
- Continuous optimization based on operational feedback
Business Impact Analysis
Operational Benefits
Energy Efficiency:
- 23% more energy delivered to fleet (960kWh vs 780kWh)
- Reduced demand charges through optimized power utilization
- Lower cost per kWh delivered due to improved efficiency
Fleet Readiness:
- Higher average state of charge across fleet
- More vehicles reach minimum operational charge levels
- Reduced risk of vehicle unavailability due to insufficient charge
Infrastructure Utilization:
- Better return on InCharge Energy charger investment
- Extended equipment life through optimal operating conditions
- Reduced need for additional charging infrastructure
Economic Analysis
For a 20-vehicle fleet with 300 charging days annually:
Energy Cost Savings:
- Improved efficiency: 180kWh additional daily energy
- Annual additional energy: 54,000kWh
- At $0.12/kWh: $6,480 annual savings
Operational Value:
- Reduced vehicle downtime from inadequate charging
- Improved fleet utilization and scheduling flexibility
- Enhanced vehicle availability for critical routes
Conclusion: Optimizing Fleet Performance
The InCharge Energy platform's ability to implement sophisticated power management algorithms delivers measurable benefits for fleet operators facing power constraints. Sequential high-power charging consistently outperforms balanced distribution in:
- Total energy delivered: 23% improvement
- Fleet readiness: Higher average state of charge
- Operational efficiency: Better equipment utilization
- Economic performance: Lower cost per mile driven
For fleet operators deploying InCharge Energy solutions, the choice is clear: intelligent sequential charging maximizes the value of both electrical infrastructure and charging equipment investments while ensuring optimal fleet readiness.
The InControl platform's advanced power management capabilities transform a simple power constraint into an opportunity for optimization, delivering superior outcomes for fleet operations at scale.
Less math-y versions of this article available on Substack and Medium.
This analysis reflects typical performance characteristics for InCharge Energy deployments. Actual results may vary based on site-specific conditions, vehicle mix, and operational requirements. Contact InCharge Energy for site-specific modeling and optimization recommendations.