What Dynamic Load Balancing Is
Dynamic load balancing is a control method that automatically adjusts the power delivered to multiple EV chargers in real time so the site stays within safe electrical limits while maximizing charging availability. It “shares” available capacity across chargers based on current demand and constraints, rather than giving every charger a fixed maximum power.
It’s commonly used in workplaces, destination sites, depots, and residential multi-tenant buildings where many chargers share one supply connection.
Why Dynamic Load Balancing Matters
Without load balancing, simultaneous charging can overload the supply and cause trips or expensive upgrades. Dynamic load balancing helps:
– Prevent breaker trips and overheating by respecting a site power cap
– Reduce peak demand and improve cost control (especially where demand charges apply)
– Allow more chargers to be installed on the same connection capacity
– Improve fairness or priority-based charging outcomes
– Enable scalable depot operations with predictable performance
How It Works
A dynamic load balancing system typically uses:
– Real-time measurement of site load (CT clamps or meters)
– A controller (charger master, CPMS, or EMS)
– Control logic that sets per-charger current or power limits every few seconds/minutes
The controller calculates available headroom and then allocates power across chargers using policies such as equal sharing, priority rules, or departure-time scheduling.
Common Allocation Strategies
– Equal share: all active chargers get the same available power
– First-come-first-served: earlier sessions get more power (less common in fleets)
– Priority-based: allocate more power to selected users/vehicles (fleet, VIP, early departure)
– Minimum viable first: give many vehicles a baseline charge, then top-up
– Phase-aware balancing (AC): distribute load evenly across phases to avoid imbalance
Dynamic Load Balancing vs Static Load Limiting
– Static load limiting: fixed maximum per charger or per group (simple but inflexible)
– Dynamic load balancing: adapts continuously to actual site conditions and number of active sessions (more efficient and scalable)
Where It’s Used in EV Charging
– Workplace charging: many cars arrive in the morning and stay for hours
– Destination charging: variable dwell time and unpredictable peaks
– Depot charging: simultaneous plug-in events after shifts (often combined with scheduling)
– Multi-tenant residential: limited building supply shared across many residents
Key Design Considerations
– Define the correct site cap: grid connection, main breaker, transformer, cable limits
– Choose control architecture: in-charger group control vs CPMS vs EMS
– Ensure safe fallback behavior if communications fail (default low limit)
– Handle measurement accuracy and update speed (avoid overshoot spikes)
– Plan for phase balancing in three-phase AC installations
– Integrate with pricing/access rules if needed (employee vs visitor, fleet priorities)
Common Pitfalls
– No real site measurement → “dynamic” control is guessing
– Site cap set too high → trips still happen
– Site cap set too low → vehicles leave undercharged unnecessarily
– Poor phase balancing → one phase overloads while others are underused
– No priority logic in depots → critical vehicles don’t get charged on time
– Weak connectivity planning → controller can’t reliably push setpoints
Related Terms for Internal Linking
– Load management
– Depot power management
– Dynamic load management
– Peak shaving
– Site power cap
– Charging schedules
– Diversity factor