The Car, the Circuit, and the Unit on the Wall
The first ceiling is inside the car. Every electric vehicle carries its own equipment to convert the alternating current from your house into the direct current its battery uses, and that equipment has a fixed limit. Whatever the wall unit is capable of, the car will accept up to its own figure and not one amp beyond it. On a good many vehicles that figure is well under what a modern charger can supply.
The circuit sets the second one. A charger is a continuous load, so the circuit is sized above the draw with margin, and the unit's working current is set at commissioning to fit inside what the circuit and the panel can carry. Somebody chooses that number on the day. It is not a property of the box.
Last comes the unit on the wall, which is the only one of the three anybody shops for. It matters only when it is the lowest. Where the car accepts less than the circuit could deliver, a larger unit changes nothing you will ever notice, and the installation is where the attention belongs instead.
What Drivers Ask Before Booking
1.Should I buy the biggest charger I can?
Only if the car can use it. A good many cannot. Where the vehicle's own limit is below what a smaller unit already delivers, the extra capability sits idle. The argument for buying larger is about the next car, and it is a real argument, but it belongs in the conductor and the conduit more than in the box on the wall.
2.My charger says it can do more than I am getting.
Three things could be limiting it, and only one of them is a fault. The car's own ceiling, the current the unit was set to at commissioning, and the circuit behind it. The first two are settled by reading numbers. Where those two do not explain the figure you are seeing, the circuit should be read under load, because a connection that is heating will also be restricting.
3.Does charging get slower as the battery fills?
On a home AC installation, much less than people expect. The pronounced tapering drivers notice belongs to high-power roadside charging. At home, the rate is close to flat for most of the session and then eases near the top. If yours slows sharply and early, mention it. That is a reading we would want to take.
4.Can I put it on the circuit the dryer uses?
Not in the ordinary sense, because a charging circuit supplies the charger and is not wired so that two ordinary loads can draw on it at once. There are recognized arrangements that appear to be exceptions, including a listed interlock that allows only one of the two to be energized at a time, and listed equipment that manages a shared total. Both are real options on some houses, and both are a different conversation.
5.What if I am not sure which car I am buying yet?
Then size the circuit for the higher of the figures you are considering and set the unit for whatever arrives. The conductor is the part you cannot change afterward without opening the wall, so it is the part to decide generously.
Everything Else We Cover in Ahwatukee
A charger is often the first hard question a garage has faced. Also from us here:
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