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Dynamic Load Balancing for EV Charging: How It Works & Benefits

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Dynamic load balancing (DLB) is a control function that adjusts EV charging power in real time to the electrical capacity a site has available. When the building uses more power, the chargers slow down. When the building uses less, they speed up. The site’s main connection never exceeds its limit.
For commercial properties, DLB often decides whether a charging project needs a costly electrical service upgrade. This guide explains how it works, how it compares with static load balancing and smart charging, how to size it with a worked example, and how to set it up and test it.
Key takeaways:
  • DLB measures the site’s live load and sets the chargers’ combined power to whatever capacity remains.
  • It can avoid or shrink a service upgrade, which is often the largest single cost in a commercial charging project.
  • Static load balancing caps chargers at a fixed limit. DLB uses the spare capacity that a fixed limit leaves unused.
  • Every DLB design needs a fallback limit for when the meter or communication link fails.
  • DLB does not replace breakers, cable sizing, or electrical design. It works within them.
Dynamic load balancing in EV charging
source: mg.ccnull.de

What Is Dynamic Load Balancing for EV Chargers?

Dynamic load balancing continuously sets the total EV charging power to the difference between the site’s connection limit and its current non-EV load. The chargers then divide that power among connected vehicles.
Every commercial building has a maximum electrical capacity set by its main breaker, service size, and transformer. Adding many EV chargers can push total demand past that limit. There are three ways to respond:
  1. Upgrade the electrical service to cover the worst case.
  2. Cap the chargers at a fixed limit, which is static load balancing.
  3. Adjust the chargers in real time, which is dynamic load balancing.
The word “load management” often appears as a synonym. In this article, load balancing means sharing capacity among chargers, and load management is the broader term that includes priorities, schedules, and prices.

How Does Dynamic Load Balancing Work?

DLB works in a repeating loop: measure the site load, calculate the spare capacity, share it among the chargers, and repeat every few seconds.
The list below shows the control loop step by step.
  1. Measure. A meter or current transformer (CT) at the main incomer reads the current on each phase.
  2. Calculate. The controller subtracts the non-EV load from the configured connection limit, minus a safety margin. The result is the EV budget.
  3. Distribute. The controller divides the EV budget among the active charging sessions.
  4. Command. Each charger receives a current limit and applies it through the vehicle’s charging signal. Chargers using OCPP receive the limit as a charging profile.
  5. Repeat. The loop runs continuously, so charging power follows the building’s demand.

What Are the Key Parts of a DLB System?

Component Role
Site meter or CT Measures the total site current on all phases
Controller Runs the algorithm; sits in a charger, a gateway, or the cloud
Chargers Apply the current limit to each vehicle
Communication link Carries meter data and commands (for example RS485/Modbus, Ethernet, or OCPP)
Configuration Holds the connection limit, safety margin, fallback limit, and priorities

What Is the Minimum Charging Current?

Most AC charging standards set a minimum charging current of 6 A per phase. If the EV budget falls below 6 A per active vehicle, the controller must queue or pause some sessions instead of slowing all of them further. This limit matters when you size a site, as the example below shows.

What Is the Difference Between Static, Dynamic, and Smart Charging?

Static load balancing uses a fixed limit, dynamic load balancing follows live site load, and smart charging adds outside signals such as prices or departure times. The table below compares them.
Feature Static load balancing Dynamic load balancing Smart charging
Limit Fixed Follows live site load Follows schedules, prices, or grid signals
Needs a site meter No Yes Depends on the function
Uses spare capacity No Yes Depends on the function
Best for Small sites, predictable loads Sites with variable building load Sites with tariffs, solar, or fleet schedules
Relative complexity Low Medium Higher
DLB is one smart-charging function. A site can combine DLB with priorities, time-of-use pricing, and solar surplus charging on the same controller.

How Much Does Dynamic Load Balancing Save? A Worked Example

DLB saves money by fitting more chargers onto an existing connection, which avoids an upgrade. The example below is an illustrative estimate, not a quote.
Site: an office with ten 11 kW three-phase AC chargers on a 400 V connection.
Item Value
Main connection 250 A per phase (about 173 kW)
Building load, peak / minimum 170 A / 60 A
Chargers 10 × 11 kW (16 A per phase each, 160 A total)
Without load balancing: peak building load plus full charging equals 170 A + 160 A = 330 A. That is 80 A above the 250 A connection, so the site needs an upgrade.
With static load balancing: the EV budget is fixed at the worst-case value, 250 A − 170 A = 80 A. Each charger gets 8 A, about 5.5 kW.
With dynamic load balancing: the EV budget follows the building. At the 170 A peak it is 80 A, the same as static. When the building drops to 60 A, the budget rises to 190 A, so all ten chargers run at their full 160 A.
Scenario EV power at building peak EV power when building is quiet Illustrative energy over an 8-hour day*
Static (fixed 80 A) About 55 kW About 55 kW About 440 kWh
Dynamic About 55 kW About 110 kW About 775 kWh
*Assumes the building stays below 90 A for 6 of the 8 hours.
What this shows:
  • Static balancing works, but it wastes the spare capacity for most of the day.
  • Dynamic balancing delivers roughly 75% more energy in this example without any service upgrade.
  • At the worst-case peak, 80 A still supports up to 13 vehicles at the 6 A minimum, so a ten-charger site works.

How Does This Compare with an Electrical Upgrade?

The upgrade would add 80 A of capacity. In the commercial EV charging cost guide, panel upgrades run about $5,000–$25,000, and a transformer upgrade adds tens of thousands more. A site meter or CT set and commissioning for DLB typically costs a few hundred to a few thousand dollars per site, plus any software licence. These are planning estimates, so confirm current quotes.

How Do You Convert Amps to kW?

Use the power-per-amp figures in the table below, which assume a power factor near 1.
Supply kW per amp (per phase, all phases loaded)
400 V three-phase 0.69 kW per A
480 V three-phase 0.83 kW per A
208 V three-phase 0.36 kW per A
240 V single-phase 0.24 kW per A

Do You Need Dynamic Load Balancing?

You need DLB when charger demand could exceed the site’s spare capacity or when an upgrade would cost more than a control system. The checklist below helps you decide.
DLB is a strong fit when:
  • Several chargers share one connection.
  • Building load varies during the day.
  • The utility quotes a costly upgrade or a long lead time.
  • You plan to add chargers in phases.
  • Demand charges make peak power expensive.
DLB may not be needed when:
  • One or two chargers have ample dedicated capacity.
  • The site has a separate, oversized supply for charging.
  • Building load is small and constant, so a static limit wastes almost nothing.

Which DLB Architecture Should You Choose?

The right architecture depends on site size, charger brands, and whether you use a cloud platform. The table below compares the three common options.
Architecture How it works Strengths Limits Best for
Charger-integrated (local master) One charger acts as master and manages others over a local network Low cost, works offline Limited to compatible chargers and site size Small to mid-size sites
Standalone controller or gateway A dedicated device reads the meter and commands chargers Supports mixed hardware, strong local safety Extra hardware and commissioning Mid to large sites
Cloud platform (CSMS) Server calculates limits and sends OCPP charging profiles Portfolio management, priorities, pricing Needs a reliable connection and a local fallback Multi-site operators
Many sites combine a local layer, which enforces the electrical limit, with a cloud layer that sets schedules and priorities.

Why Should the Electrical Limit Be Enforced Locally?

The connection limit protects the site, so a lost internet link must never leave it unprotected. A local controller keeps the limit in force during outages, while the cloud handles priorities and reporting.

How Do Chargers Share the Available Power?

Chargers share power through a distribution mode, which decides how the EV budget is split among active sessions. The list below shows the common modes.
  • Equal sharing: every active vehicle gets the same current.
  • First come, first served: early arrivals charge at full rate, and later ones wait or receive the minimum.
  • Priority-based: designated vehicles or users, such as fleet vans with early departures, get power first.
  • Phase balancing: the controller spreads single-phase and three-phase loads so no phase carries more than its share.
  • Solar surplus or price-based: the controller raises charging power when on-site solar or low prices allow it.

What Happens If the Meter or Communication Fails?

If the controller loses the meter or a link, it must switch to a fallback limit that keeps the site safe without live data. A fallback limit is a fixed EV current, sized for the building’s worst-case load.
In the worked example, the fallback limit is 250 A − 170 A = 80 A total EV current. The controller applies it, or pauses charging, until the data returns. Define three behaviors before commissioning:
  1. Meter lost: apply the fallback limit.
  2. Charger link lost: the charger falls back to its stored safe current.
  3. Controller lost: chargers default to a configured safe limit or stop.

How Do You Set Up Dynamic Load Balancing?

A DLB setup follows seven steps, from measuring the site to monitoring live performance. Start with data, because a limit that ignores real building load is either unsafe or wasteful.
  1. Audit the site load. Collect at least 12 months of interval demand data, ideally 15-minute readings, and note the peak and minimum.
  2. Define limits. Set the connection limit, a safety margin (a 5%–10% buffer is a common practice), and the fallback limit.
  3. Choose the architecture. Pick local, controller-based, or cloud control from the comparison above.
  4. Place the meter correctly. Measure at the point that includes all building loads, on every phase. Check meter accuracy and the communication protocol.
  5. Configure the chargers. Set the maximum and minimum current, distribution mode, and any subgroups for circuits with separate limits.
  6. Commission and test. Simulate a meter failure, a sudden load step, and a full house of vehicles. Confirm that the limit holds in each case.
  7. Monitor. Review the current per phase, throttling events, and session counts, and adjust the limits as the site grows.

What Are Common DLB Mistakes?

The list below covers the errors that most often cause nuisance trips or wasted capacity.
  • Placing the meter where it misses part of the building load
  • Setting no safety margin, so small measurement errors cause overloads
  • Skipping fallback testing
  • Ignoring phase imbalance from single-phase vehicles
  • Forgetting the 6 A minimum current when sizing multi-charger sites
  • Treating DLB as a substitute for correct breaker and cable sizing

What Codes and Standards Apply?

DLB must operate within the local electrical code and the charger’s listing. The exact rules depend on the region and code edition, so confirm them with the local authority before design.
  • Charging control: AC charging communication follows IEC 61851-1, which defines the control signal and the 6 A minimum.
  • Communication: OCPP 1.6J and 2.0.1 support charging profiles that a platform can use to limit power.
  • United States: NEC Article 625 covers EV charging equipment, and Article 750 covers energy management systems. Confirm the edition your local authority has adopted and whether it accepts load management to size the service.
  • Europe and other regions: national wiring rules and grid operator requirements apply.
DLB limits the current the chargers draw. It does not remove the need for correctly rated breakers, cables, and protection.

How Does DLB Reduce Operating Costs?

DLB reduces operating costs by lowering peak demand and avoiding oversized service. Utilities often bill commercial customers for their highest power draw in a billing period. Capping EV demand keeps that peak lower.
The strongest savings come from combining DLB with time-of-use pricing, battery storage, or solar surplus charging. Model the tariff before choosing a charger power level, because the tariff can change the payback more than the hardware does.

How Does EV-TOP Support Dynamic Load Balancing?

EV-TOP supplies AC and DC chargers across power levels, with customization through its OEM/ODM programs. For buyers building load-managed sites, that means one supplier can match charger specifications to the site’s capacity.
Where EV-TOP customization applies to load management:
  • Charger current and power ratings set to the site’s real capacity
  • Communication interfaces and protocols that match the chosen controller
  • Firmware behavior, such as fallback current and minimum current settings
  • Connector, enclosure, and branding options for resale programs

Dynamic Load Balancing FAQ

What is dynamic load balancing in EV charging?
It adjusts charging power in real time to the electrical capacity a site has free, so the main connection never exceeds its limit.
What is the difference between static and dynamic load balancing?
Static uses a fixed power limit. Dynamic follows live building load and uses spare capacity that a fixed limit leaves idle.
Does dynamic load balancing need a smart meter?
It needs a measurement of total site current, usually from a dedicated site meter or CT. A utility smart meter serves a different purpose.
Can dynamic load balancing avoid a service upgrade?
Often, yes. Many sites add chargers within the existing connection by controlling their combined power. The design must still meet code and the utility’s rules.
What happens if communication fails?
The controller applies a preset fallback limit or pauses charging until reliable data returns.
How many chargers can share one connection?
It depends on spare capacity and the 6 A minimum current. In the worked example, 80 A of budget supports up to 13 vehicles at the minimum rate.
Does load balancing slow down charging?
It slows charging only when the site is near its limit. Most of the day, chargers run at or near full power.
Does it work with mixed charger brands?
It can, if the controller supports open protocols such as OCPP or standard meter interfaces. Test the integration for each hardware combination.
Is load balancing the same as smart charging?
No. Load balancing is one smart-charging function focused on limited capacity. Smart charging also covers prices, schedules, and solar.
Does it harm the vehicle battery?
No. It changes charging current within the limits the vehicle and charger already allow.

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