Why does 110 charge the car at 3mph, but 220 charge at 35mph? It’s 2x volts but >10x charge speed.
In: Physics
Its not just about the voltage, its also about the available current which results in a lot more available power
The 120V chargers are meant to be plugged into any outlet so they’ll be limited to 15A for a mere 1.8kW of input power. Outlets in your home are on 15 or 20A breakers so they can’t really assume for more than about 15A and have it not trip breakers, the slower ones are going to be even below this 15A threshold to keep them small and portable, a 1kW+ power supply generally weighs several pounds and requires heatsinking because even 95% efficiency is a lot of heat trapped in the box
The 240V charges are installed by an electrician and are more permanent installations. Generally they’ll be put on a 30A or 40A breaker similar to an electric water heater. So while it seems that *all* you did was double the voltage, its actually double the voltage *and* over double the available current. A 240V charger on a 40A breaker could pull 9.6 kW to charge with which is 5x the available power, and well over 5x the reasonably available power.
Because 220/240 volt circuits can be fitted with much higher-amperage breakers. A typical 115v circuit has a 15 amp breaker with a max charge current of 12 amps. A 240 circuit can have a 50+ amp breaker which gives a max charge current of 35-40 amps or higher.
Charge rate is a measure of power. Power is voltage * current. So if you increase both the voltage and the current, you dramatically increase the power.
The key here isn’t so much the voltage as the current available on the circuit the car is charging on.
In theory you could build a very high current 115V circuit but this is not commonly done for a lot of reasons.
I’m not sure how you’re getting from volts to speed. But I can explain a bit about electricity. The amount of power being put into something is related to both current and voltage: Power=Volts x Current. When you double the voltage, it also doubles the current, so you get 4x the power from 2x the voltage.
So at the same higher voltage circuits tend to be able to handle much more power. Chances are that the charging on 110v is limited by the house’s circuit limit. The 220V circuit is most likely sized to handle a lot more power going through it.
Speaking for the US electrical system.
The differences is in the Amperage through the circuit breaker, and how many wires are carrying power. 110VAC power is on a single power wire, and limited to 20 amps by the circuit breaker. 220VAC (three phase) power is carried on three wires, and limited by a 50 amp circuit breaker.
The 110 VAC has a potential of approx 2,200 watts of potential power, The 220VAC has approximately, 19,000 watts of potential power. The 220VAC three phase can delivery approximately 860% more power than the 110VAC
From what i have seen, in certain parts of Europe, the 220 is brought in on a single wire ,and limited by a 50 amp breaker, it has approximately 11,000 watts of potential power. The 220VAC single phase can delivery approximately 500% more power than the 110VAC
Charging speed depends on the voltage at the outlet AND the amps that the wiring can carry. Most charging equipment has safety measures, such as overheating protection, to make sure it doesn’t melt or catch fire. Using extension cords, especially with 110V chargers, will significantly slow down charging because of the added resistance.
Can I ask what this is in reference to? Do you have a link to what you’re talking about?
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