Guide
Home load balancing: charge without overloading your connection.
An EV charger is often the largest load in a home. Load balancing lets the charger use only the capacity the house is not using, so you can charge quickly without tripping the main breaker or upgrading the connection.
The problem: one connection, many loads
Every home has a maximum current per phase set by its connection and main breaker. An 11 kW charger draws 16 A per phase and a 22 kW charger 32 A per phase. Add an oven, a heat pump or a water heater and the total can exceed the limit.
Without load balancing, the installation has to be sized for the charger at full power plus everything else at the same time, or the charger has to be set permanently to a low current.
How load balancing works
The charger reads the main energy meter of the house, connected by Modbus RS485 or over Wi-Fi, to know how much current the house is drawing. With that information it continuously adjusts its own charging current so that the total stays below the limit you configure and the main breaker does not trip.
When the house uses little power, for example at night, the car charges at full power. When other appliances switch on, the charger reduces its current, and it increases it again when they switch off.
An example
Take a connection with 25 A per phase and a charger set to that limit. The table shows how much current is left for the car as the household load changes.
| House load per phase | Available for the car | Approx. charging power (3 phases) |
|---|---|---|
| 5 A | 20 A | about 14 kW, limited to the charger rating |
| 10 A | 15 A | about 10 kW |
| 18 A | 7 A | about 5 kW |
Below the minimum
AC charging works with a minimum current, around 6 A per phase under IEC 61851. If the spare capacity drops below that, charging typically pauses and resumes automatically when capacity is available again.
Do you need it?
Load balancing is most useful when the connection is limited, when there are large loads such as heat pumps or electric water heaters, or when you choose a 22 kW charger on a connection that cannot always deliver 32 A per phase.
It is also the simplest way to add a charger to a building without increasing the contracted power or upgrading the connection.
Load balancing on Bora chargers
Configurable home load balancing is available as an option on the Bora 11 and Bora 22, and included on the Bora 22 Pro. The charger connects to the main meter of the house by Modbus RS485 or Wi-Fi. Tell us your connection and meter and we will define the setup with you and your electrician.