With more households in Broxbourne owning two electric vehicles, the need to charge both cars at the same time is becoming more common. Many homeowners assume that if you have two chargers or a charger with two sockets, both cars simply charge at full power. But that isn’t how most EV chargers behave.
What your EV charger actually does when two vehicles try to charge at once is far more complex. Behind the scenes, the charger, your home wiring, and sometimes even your electricity supplier work together to decide how much power each vehicle receives. This process is known as load management, and understanding it can prevent slow charging, tripping circuits, or overloading your home’s electrical system.
In this blog, we’ll explain exactly what happens the moment two EVs plug in simultaneously, why this matters in Broxbourne homes, and what solutions an electrician can provide to ensure safe and reliable charging.
Why Two-Car Charging Is More Common in Broxbourne
Broxbourne has a high number of family homes, often with two drivers and two cars. As more families transition to electric vehicles, the number of households needing dual charging increases. Many properties in the area also have off-street parking, making home charging the most convenient option.
But what many homeowners do not realise is that most domestic electrical systems were never designed for two high-demand charging points. Without the right charger or load balancing system, attempting to charge two EVs can put unnecessary strain on the property’s wiring.
What Happens the Moment Two Cars Plug In
Most modern EV chargers have built-in safety and power management systems. When two EVs connect at once, the charger immediately evaluates several factors before delivering power.
Here’s what it checks:
1. The maximum load your home can safely handle
Your charger calculates how much spare capacity is available on your main electrical supply. In most Broxbourne homes, that supply is 60 or 80 amps. Charging two EVs at full power could exceed this, so the charger must reduce output if needed.
2. The maximum load allowed by the charger itself
Some chargers can support dual charging but only up to a combined limit. For example, two cars may share one 7kW limit rather than each receiving 7kW.
3. The charging priority setting
Certain chargers allow you to decide which car gets priority. If this is set, the charger directs most or all power to the priority vehicle while slowing the second one.
4. The real-time energy use inside your home
If your oven, heating, washing machine, or electric shower are running, the charger automatically lowers output to avoid overload. When two EVs are plugged in, this reduction is even more important.
5. The capabilities of each car
Different EVs accept different charge rates. Your charger also checks what each vehicle can handle.
These checks all happen within seconds of plugging in.
How Your Charger Shares Power Between Two Cars
Once the charger has assessed the available power, it distributes energy between the vehicles in one of the following ways:
Equal load sharing
Both cars receive half the available power.
Example: If 7kW total is available, each car receives around 3.5kW.
Dynamic load sharing
Power is constantly adjusted based on:
- Home energy usage
- Which car is closer to full
- Circuit load
- Temperature
This ensures safe charging without overloading the property.
Priority charging
One vehicle charges at full power.
The second car waits or receives whatever spare power remains.
This is helpful when one driver needs a full charge for the next morning.
Sequential charging
Some chargers alternate between cars. For example, Car A may charge from midnight to 3 AM, then Car B charges from 3 AM onward. This is common with older dual-charging setups.
Why Some Homes in Broxbourne Experience Tripping or Very Slow Charging
Even though chargers are built to manage load safely, homes with older wiring or small supply sizes may still struggle. Here are the most common issues we see in Broxbourne:
1. Old consumer units
Older fuse boxes often cannot handle the additional load of a second EV charger. This can lead to nuisance tripping or overheating.
2. No load management system installed
Some installations from years ago did not include dynamic load balancing. Without it, two cars charging can overload the supply.
3. Incorrect cable sizing
If the original charger wiring was only sized for a single vehicle, adding a second charger later can push the circuit beyond its safe limit.
4. Shared circuits
In some properties, chargers share a circuit with other appliances, causing slow charging or tripping during heavy usage.
5. Supply size limitations
If your home has a 60 amp main fuse, there may simply not be enough spare capacity for dual charging without an upgrade.
How to Make Two-Car Charging Work Safely in Your Broxbourne Home
If you want reliable two-car charging, a few upgrades may be needed.
Install dynamic load balancing
This is the most important upgrade. It allows the charger to:
- Detect your home’s real-time energy use
- Adjust charging speed automatically
- Prevent overloads
Upgrade the consumer unit
Modern RCBO protection and higher-rated busbars help the electrical system handle EV loads safely.
Consider a dual-socket charger
These units are designed specifically for two vehicles and manage load more efficiently.
Request a supply upgrade from your energy provider
Increasing your household supply to 80 or 100 amps may improve charging capacity.
Use timed off-peak charging
Charging at different times overnight reduces strain on your system.
When to Call an Electrician
If you notice:
- Slow charging
- One car refusing to charge
- Frequent tripping
- Hot consumer unit
- Error messages about load or supply
then your system needs assessment.
Book an EV Charging Assessment in Broxbourne
JJB Electrical specialises in EV charger installations, upgrades, and dual charging solutions in Broxbourne. We ensure your system is safe, compliant, and capable of charging two vehicles without problems. 📞 Call JJB Electrical on 01992 276087. Your local EV charger specialists in Broxbourne
