How Tesla Charging Works
Tesla's charging system is robust and adaptable and functions in several steps. Tesla vehicles contain onboard devices that regulate current (and, in some cases, convert current) to charge the thousands of lithium-ion battery cells contained underneath the floor.
When the car is plugged in, the system determines if it's receiving AC (alternating current) or DC (direct current) power from the source. If it receives direct current, electricity passes through the regulating system and enters the batteries. If it's alternating current, it passes through onboard inverters, which convert it to the DC current that the batteries can use.
Battery cells themselves have no system that prevents overcharging, which is hazardous due to the heat and damage it produces. However, Tesla's onboard computers monitor charge levels and disconnect the current what's the batteries are full. Sophisticated systems also work with several different voltage and current levels.
Tesla Charge Controllers
Tesla has charge controllers built into the vehicle, but many charging stations also have charge controllers. The fastest Tesla charging systems utilize computers to regulate current and voltage, as the flow of electricity from these devices is much higher than a standard 120-volt wall outlet.
You don't technically need an external charge controller to charge a Tesla. However, the lack of a charge controller limits you to lower voltage and less current, which means it will take significantly longer using an unregulated wire than it would with a more sophisticated system like the Tesla Wall Charger.
Can You Plug a Tesla Directly Into an Outlet?
Yes, you can plug a Tesla directly into a standard wall outlet in your home. Most three-prong home outlets provide 110 or 120 V at 15, or 30 A. Most homes also have a larger 240 V AC outlet in the garage that provides 30 or 60 A. Tesla vehicles can be charged using both of these outlets, though the standard wire charger only fits in a three-prong 120 V outlet.
Tesla Charging Adapters
You can't just plug an extension cord into your car. Tesla uses a proprietary plug that somewhat resembles a gas pump, and it's designed to handle extremely high voltages that some charging stations provide. As a result, you'll need an adapter to plug your Tesla into a standard wall outlet.
Your Tesla will come from the factory with a 110/120 V charging cable. This is the cable you can plug directly into a standard wall outlet or any other receptacle that has a standard plug on it. The technical designation for this plug is NEMA 5-15.
Slow Charging Vs Fast Charging
Most charging setups are considered 'slow charging' by Tesla. That includes the 110/120 V charging cord that comes with your car. AC power systems charge at varying rates, but Tesla's fast Superchargers use DC exclusively. Most homes don't have a DC connection, and the vast majority of AC generators can't produce enough DC current to charge a Tesla in this way.
Can You Use a Generator to Charge a Tesla?
While a standard generator won't charge a Tesla in DC, it certainly can (albeit slower) in 110 V, 120 V, or 240 V AC. Many generators can produce enough power to charge a Tesla, and they're a viable emergency charging tool for power outages, camping, or off-grid living. Here's a little more about generators and how you can use them to charge your Tesla.
Types of Generators
Generators are machines that burn fuels such as gasoline or diesel in an engine to produce electricity. Generators aren't all the same, and it's important to know the difference between common types before choosing one to charge your Tesla. Here are the most common kinds of generators.
When you think of a generator, you're probably thinking of a gasoline-powered model. These are by far the most common, and they're available at hardware stores and outdoor outlets. Gasoline-powered generators are distinct from gas-powered generators, which burn compressed natural gas or propane.
Gasoline generators are affordable and usually start at around $250-$300. Most of these inexpensive units have small fuel tanks and don't produce a lot of power, but they can produce 110 V at 15 A and sometimes more.
Diesel generators are much more efficient than gasoline-powered generators. However, you're not likely to find a small portable diesel generator. Diesel is reserved for larger units, such as emergency backup generators and industrial units. The vast majority of diesel generators can produce more than enough power to charge a Tesla.
Natural Gas Generators
Natural gas generators are typically found in rural homes. These generators act as a backup, and many of them start automatically. The majority of natural gas power generators are fixed, meaning they aren't portable. These generators are designed to run an entire home for an extended period of time. They are also often installed in tandem with solar panels.
Portable generators are the kind you can buy from the hardware store. They usually have between one and six power outlets, and they usually don’t have a starter. These generators are reliable, but cheaper models aren't designed to run for days on end.
Fixed generators are used for generating power for extended periods of time. Natural gas generators are often fixed and wired up as a primary or secondary source of power in remote areas. These generators are the most eco-friendly but also the most costly.
What Kind of Generator Will Charge a Tesla?
Most generators that can produce 110 for 120 V (at 15 or 30 Amps) can charge a Tesla. Generators that produce 240 V are much better suited for the task, but even a small portable generator can charge a Tesla to some extent.
How Fast Will a Generator Charge a Tesla?
Generators won't charge your Tesla quickly. The charging speeds you'll achieve will resemble what you get with a standard 120 V wall outlet. Charging with 110 V or 120 V AC power is essentially trickle charging, and you typically gain about 4 miles of range for every hour that it's hooked up to the system.
That's about 30 miles of range per night of charging, which is quite slow. However, upgrading to a 240 V generator can dramatically increase your charging speeds. This is the voltage that the Tesla Wall Charger operates at, and it can charge at a rate of 30 miles per hour of charging.
Best Generator for Charging a Tesla
Generators have limitations, and some are better suited for charging Tesla vehicles than others. The smallest generator we'd recommend using is about 6500 Watts, which is in the middle of the road for portable gasoline models. A 9000 W or 10000 W generator would be a significant improvement, and probably more efficient as well.
The ideal generator and charging a Tesla will come with a 240 V outlet. You can use a 110 V generator, but it will charge at less than 1/5 of the speed. A 240 V generator will charge your Tesla rapidly in comparison and offers much better range and less fuel consumption.
The ideal setup would include an integrated, fixed natural gas or diesel generator that's wired into your home power system. When paired with a Tesla Power Wall or a Wall Charger, it will seamlessly charge your Tesla just as fast as grid power and with cleaner emissions than a portable unit.
Are Generators Worse than Driving a Conventional Car?
Using a generator to charge your Tesla every day is probably worse for the environment than driving a conventional gasoline or diesel-powered car. The vast majority of cars on the road were designed with strict emission standards that limit harmful particulates.
Generators, on the other hand, are not subject to the same rules. Additionally, they're not nearly as efficient. You'll probably burn more fuel and release dirtier fumes with a generator than you would with a car, even if you charge your Tesla to drive the same distance.
Natural gas generators may be an exception, but it's very difficult to calculate. Regardless, a generator will never be as efficient as a large power plant, so using a generator to charge a Tesla will emit more per mile than using the grid.
Off-Grid Tesla Charging
If you're setting up an off-grid electrical system for your home, you may be pleasantly surprised to learn that the Tesla Power Wall can be integrated into your system. The Power Wall can wire up seamlessly with a combination wind, solar, and generator system, or any other configuration you choose.
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding