1 Family Charger End Charging Wars?

This article answers whether a single family charger can end charging wars in a household. The short answer is yes, but only if the charger is set up with enough power and a scheduling system; otherwise, it just moves the argument to a new device. We explain how a single charger can work for multiple vehicles, how to choose one, and what limits you will still face.

Formula

The calculator works out how much charge power a single home charger must deliver to cover a household’s daily driving, given the time available for charging. The formula is:

Required power (kW) = (Daily distance × Efficiency) / (100 × Charge time)

Where:

• Daily distance (d) is the total kilometres driven by all household vehicles in a typical day.
• Efficiency (e) is the average energy consumption of the vehicles, in kWh per 100 km.
• Charge time (t) is the number of hours the charger is actually in use each night.

The result is the minimum continuous power output the charger must provide. For example, if your household drives 60 km per day, the vehicles use 18 kWh/100 km, and you have 8 hours to charge, you need 60 × 18 / (100 × 8) = 1.35 kW. That is very low; most home chargers deliver 7 kW or more, so the real bottleneck is usually the vehicle’s onboard charger or the circuit capacity, not the wall unit.

Worked Example

Using the default values from the calculator:

1. Daily distance = 60 km
2. Efficiency = 18 kWh/100 km
3. Charge time = 8 hours

Step 1: Energy needed per day = 60 × 18 / 100 = 10.8 kWh.

Step 2: Required charger power = 10.8 / 8 = 1.35 kW.

So a charger that delivers just 1.35 kW continuously for 8 hours would cover the household’s daily driving. In practice, most wall boxes provide 7.4 kW (single-phase 32 A in many regions) or 11–22 kW (three-phase), so even one charger is far more than enough for typical daily use. The calculator shows that the “charging warâ€� is rarely about raw power; it is about who gets to plug in first when two cars need charging on the same night.

Background: Why Charging Wars Happen

Charging wars in a family usually start when two or more plug-in vehicles share one outlet or one wall box. The conflict is not about the charger itself but about time: each vehicle needs a certain number of hours to reach its target state of charge, and if both need the same night, someone loses. This is different from a petrol station, where filling takes five minutes and multiple cars can queue. An EV at home typically sits plugged in for several hours, so a single charger becomes a shared resource that must be scheduled.

Another factor is that many households buy a second EV without upgrading the electrical service. A 7 kW charger is fine for one car, but two cars each needing 7 kW for 8 hours means 112 kWh per night, which exceeds what many homes can draw. The charger is not the limit; the main breaker and the utility connection are. So the real question is not “which charger� but “how much power can the house supply and how do we share it.�

How a Single Charger Can Work for Two Cars

One charger can absolutely serve two vehicles if you manage the schedule. The simplest method is to alternate nights: car A charges Monday, Wednesday, Friday; car B charges Tuesday, Thursday, Saturday. This works if each car’s daily driving is low enough that a full charge every other day is sufficient. For example, a car with a 60 kWh battery and 400 km range driven 50 km per day only needs about 7.5 kWh per day, so a single 7 kW charger for 2 hours every other night is plenty.

A better method is to use the car’s built-in scheduled charging. Most EVs let you set a departure time and a target charge level. If both cars are plugged into the same charger via a switched socket or a dual-cable unit, you can set car A to charge from midnight to 3 a.m. and car B from 3 a.m. to 6 a.m. The charger itself doesn’t need to be smart; the cars’ timers do the work. Some wall boxes also have load balancing, which splits the available current between two cars simultaneously, but that requires a second cable and a charger with two outputs.

The key is to calculate the total energy needed per day and compare it to what the charger can deliver in the available off-peak hours. The calculator above does exactly that. If the required power is below the charger’s rated output, then scheduling alone ends the war. If it is above, you need either a higher-power charger or a second charger.

How to Choose a Single Charger for a Family

When buying one charger for a multi-EV household, focus on these factors:

• Power output: 7.4 kW is standard for single-phase; 11–22 kW for three-phase. Higher power shortens charging time but requires a thicker cable and a bigger breaker.
• Connector type: Most EVs in North America use J1772 or NACS; in Europe, Type 2. Make sure the charger matches your cars, or buy an adapter.
• Cable length: A 5–8 metre cable reaches two parking spots if the charger is mounted between them. This is the cheapest way to share one unit.
• Scheduling features: A charger with an app or a simple timer lets you set different charge windows for different cars, even if the cars themselves lack scheduling.
• Load management: If your home electrical service is limited, a charger that can communicate with a second unit or a smart meter can reduce power when the oven or heater is on.

Do not buy a charger with more power than your car can accept. For example, a Nissan Leaf (older models) accepts only 3.6 kW on AC, so a 22 kW charger will still charge at 3.6 kW. Check your car’s onboard charger rating first. Also, check whether your home has single-phase or three-phase power; a three-phase charger will not work on a single-phase supply without derating.

Common Problems and Misconceptions

One common misconception is that a higher-power charger always charges faster. In reality, the car’s onboard charger limits AC charging speed. A 22 kW wall box connected to a car that only accepts 7 kW will deliver 7 kW. The only way to get faster AC charging is to have a car with a larger onboard charger, which is rare.

Another misconception is that you need a smart charger to share it. You don’t. A simple mechanical timer or the car’s own schedule works. The problem is that many people don’t read the manual and assume the charger must be “smartâ€� to handle two cars. In fact, the charger just supplies power; the car decides when to stop. If you plug in car A at 6 p.m. and car B at 8 p.m., the charger will happily charge both simultaneously, but the total current may trip the breaker if the charger is not load-managed.

A frequent issue is that the charger’s cable is too short to reach the second car. Measure the distance from the charger location to both car ports before mounting. A 7-metre cable can often reach two adjacent spaces, but if the cars park nose-in, you may need to reverse one. Some families install a second outlet on the same circuit using a simple switch, but that requires an electrician and may not be code-compliant in all areas.

Costs and Electrical Limits

The cost of a single charger is roughly the same whether it serves one car or three, so the marginal cost of adding a second car is just the installation if you already have a charger. However, the electrical service may limit you. A typical home in North America has a 200 A main breaker, which can handle a 50 A circuit for a 9.6 kW charger (240 V × 40 A continuous). If you have electric heating, a hot tub, or an induction stove, you may need a load management system that reduces charger current when other high-power appliances are on.

In Europe, a single-phase 7.4 kW charger draws 32 A, which is often the limit for a standard household connection. Three-phase 11 kW draws 16 A per phase, which is more efficient. If your home has a 3-phase connection, an 11 kW charger is usually the best choice because it charges most EVs faster than 7.4 kW and still leaves headroom for other loads. Always have a licensed electrician verify the circuit capacity and the charger’s settings before installation.

Alternatives to a Single Charger

If scheduling and load management are not enough, consider these alternatives:

• Two chargers on separate circuits: The most expensive but simplest solution. Each car gets its own dedicated circuit, and there is no sharing.
• A dual-cable charger: Some wall boxes have two cables and can charge two cars simultaneously, but they split the total power. For example, a 22 kW dual-cable charger gives 11 kW to each car.
• Portable charger with multiple adapters: A 2.3 kW (10 A) portable charger can be plugged into a regular socket, but it is very slow and not recommended for daily use.
• Public charging for one car: If one car has a short commute, you might charge it at a workplace or a fast charger once a week, leaving the home charger for the other car.

The choice depends on how many kilometres each car drives and whether your electrical panel has spare capacity. For most families, one 7–11 kW charger with a schedule is enough. The calculator at the top of this page helps you confirm that before you spend money on a second unit.

Frequently Asked Questions

Can one charger charge two EVs at the same time?

Yes, if the charger has two cables and supports simultaneous charging, or if you use a simple splitter (not recommended). Most standard wall boxes have one cable, so you can only charge one car at a time. However, you can plug both cars in and let the car’s timers alternate, but the charger will only supply power to one at a time if you manually switch cables.

How long does it take to charge two cars with one charger?

It takes the total energy needed divided by the charger’s power. For example, if each car needs 20 kWh and the charger delivers 7 kW, charging both sequentially takes 40/7 ≈ 5.7 hours. If you have 8 hours overnight, that is feasible. If you need more than the overnight window, you need a higher-power charger or a second one.

Is it safe to use an extension cord with an EV charger?

No, not for regular charging. Extension cords are not rated for continuous high current and can overheat, causing a fire risk. Always use the charger’s built-in cable and have a properly installed outlet. If you need more reach, mount the charger closer to the parking spot or install a second outlet.

What is the difference between a 7 kW and an 11 kW charger?

The power rating determines how fast the car charges. A 7 kW charger adds about 35 km of range per hour for a typical EV (assuming 20 kWh/100 km), while an 11 kW charger adds about 55 km per hour. However, the car must support the higher rate; many cars only have a 7 kW onboard charger, so an 11 kW wall box will still charge at 7 kW.

Will a single charger increase my electricity bill a lot?

It will increase your bill by the amount of energy your cars use. If you drive 60 km per day at 18 kWh/100 km, that is 10.8 kWh per day, or about 324 kWh per month. At a typical residential rate, that is a noticeable but not huge addition. Charging during off-peak hours can reduce the cost if your utility has time-of-use rates.

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in t | Charge time available | hours | 8 | 0 | 24
in d | Daily driving distance | km | 60 | 0 | 1000
in e | Vehicle efficiency | kWh/100km | 18 | 5 | 50
out req | Energy needed per day | kWh | d * e / 100 | 2
out power | Required charger power | kW | req / t | 2