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Can You Charge A Tesla With A Generator?

Written by Jamie Masterson

Yes, technically you can charge your Tesla with a generator. But the practice is advised in emergencies only and that too only if you have an inverter unit handy. The charging time and quality will depend on the power output, outlet type, and the performance of your inverter generator.

charge a car battery with a generator

In case of emergencies, you may need to recharge your batteries in the middle of nowhere so you can take your car to the nearest charging station. In most cases, a portable generator isn’t a very practical or efficient way to charge your Tesla.

It may take 24-48 hours of your precious time and a big amount of gasoline to get your car charged. Today we’ll figure out how you can do that in the most effective way!

Slow charging vs fast charging – Do generators have an impact?

Tesla car batteries are primarily made from Lithium-ion. One specialty of these modern and advanced types of batteries is they can, with some additional help, control how fast they charge. The first 20% of your Tesla car battery will charge much faster than the last 20%.

Additionally, most charging setups are considered as ‘slow charging’ by Tesla. Most modern EVs feature 110/120 V charging cord whereas Tesla’s faster superchargers exclusively use DC. This results in a much faster charging time. Some models even can charge the full car within 30 min.

tesla panoramic

No matter what type of generator you use, you won’t be able to charge your Tesla faster. In some cases, it may take more than 24-hrs to charge your car fully.

This reason also adds to why charging your Tesla with a generator isn’t very practical. Use this method in emergencies only and don’t even think about fully charging your batteries with a generator.

What kind of generator will charge a tesla?

Not all generators will be able to charge your heavyweight Tesla batteries because they have a higher energy density than traditional batteries that require a massive wattage out of your generator.

Besides, keep in mind that Tesla doesn’t run on AC current and very few generators can actually support your Tesla car batteries.

What kind of generator will charge a tesla

Only inverter generators are able to provide the power your car battery needs. We recommend a generator with at least 1500W of wattage output.

What Types of Generators Suit Tesla Cars

Gasoline generators

These are the most common type of generators available. Just as the name suggests, these generators use gasoline (natural gas or propane)to produce power.

Gasoline generators

Gasoline generators are comparatively cheaper and most of them can’t produce enough power due to their small fuel tank. The power output they produce is considered slow charging (110 V at 15 A), but some of the high-end models can provide more power.

Diesel generators

They are comparatively more efficient than standard gasoline generators. They technically can charge your Tesla but that won’t be a viable option.

Most diesel generators will be able to charge your Tesla with ease. However, These heavy-duty generators aren’t usually portable. Diesel is kept reserved for industrial units and for emergency cases.

Diesel generators

It wouldn’t be wise to look for an industrial generator every time your Tesla is out of juice, now would it?

Natural gas generators

Just like diesel generators, most natural gas generators are also fixed in one place. They are usually seen in rural environments, installed alongside solar panels.

Natural gas generators

The lack of portability also discards natural gas generators from the list of our potential Tesla power sources.

Portable generators

These are the most potential candidates that can power your Tesla, even in the middle of nowhere. You can buy one from your local hardware store, and carry it in your trunk wherever you go.

Portable generators

Portable generators are reliable, but the cheaper ones might not be able to power your car adequately. Investing in a premium quality portable generator can solve the problem.

Things to remember before charging your Tesla with a generator

Wave type

If you want to power your Tesla car with a generator, make sure that the generator produces an unmodified, clean sine wave. The mechanism of your car is designed in a way that it won’t accept any charge from an unstable or dirty power source.

That limits your options to the inverter generators only. However, not all of them produce an unmodified, clean sine wave and your Tesla won’t accept anything but that.

Wave type

Make sure your inverter generator doesn’t feature a modified square wave or a modified sine wave. If it does, that’s not gonna be of any help.

Proper grounding

Proper grounding is essential whether you want to charge your Tesla or Toshiba. Many generators come with a built-in metallic frame that works as a grounding element.

To protect you and your car from getting electrocuted, Tesla has programmed its charging system to reject the power coming from an unsafe source.

Proper grounding

As a result, unless you ground your generator properly, the adaptor won’t receive any charge. To solve this issue, you can try purchasing an adapter plug (Edison plug) or connecting the floating neutral to the ground. A copper wire or a metal rod will do the trick.

Outlet type

The outlet type is another major concern when you want to charge your Tesla with a generator. Most portable inverter generators feature a combination of NEMA 5-20, 14-30, and 14-50 outlets.

Outlet type

Matching the outlet type is essential. Each outlet is designed to carry a definite amount of charge only and one won’t fit in another’s socket. You can use mobile adopter in case you have the wrong outlet.

Wattage

Wattage is also important to charge your Tesla EV. Each type of outlet and adapter can support a different range of power and performance. Let’s have a detailed look.

There have been two generations of Tesla adaptors so far. In case of 5-20 and 14-30 type adaptors, there is no significant change in the maximum watt and amp count in these two generations. However, there is a significant increase of maximum watt and amp count only for the 14-50 type of adaptors. Gen adaptor 1 produces 9600W, 40A whereas gen 2 can provide up to 7680W, 32A.

That being said, here’s how much mileage you can get from your generator:

Adopter Model X mileage (Per 1-hr charge) Model S mileage (Per 1-hr charge) Model 3 mileage (Per 1-hr charge) Model Y mileage (Per 1-hr charge)
Generation 1 5-20 3 4 N/A
14-30 14 17
14-50 25 29
Generation 2 5-20 3 4 4 4
14-30 14 17 22 21
14-50 20 23 30 29

Your car’s limit

No matter what model Tesla you use, your outlet type is designed to transport a certain amount of power, which will always be less than the outlet’s threshold. Your generator will most probably also have some limitations.

tesla charging port

That’s why it won’t be possible to draw out the maximum power your generator can produce. No matter how hard you try, your outlet won’t draw power beyond its limitation.

How fast will a generator charge a tesla?

That depends on the power input. If your generator only produces 110 V or 120 V AC power, it’ll be no better than connecting your Tesla to your home wall outlet. That way, the system will trigger Trickle charging and you’ll gain only about 4 miles of range for every hour.

How fast will a generator charge a tesla

On the other hand, some powerful generators can produce 240 V power output that can significantly reduce your charging time. Tesla Wall Chargers operate at that power range, allowing you to gain an astounding 30 miles per hour from your charging session.

How to Charge a Tesla with a Portable Generator?

Tesla Motors discourages you from charging your car with a portable generator in their own user manual. This isn’t a practical, efficient, or Intelligent way to power your car.

However, this method can be used in emergencies where the extra mileage you get from the generator can help you to travel to your nearest charging station. The process of charging is pretty straightforward.

Here’s the process –

One word of advice, let the generator run for a few minutes after you start the engine. Don’t plug your Tesla charger right away. The generator needs to warm up first.

Another thing, set the amps to the lowest possible setting from your dashboard monitor and then slowly increase the amps to the maximum. This will help prevent your generator from dying on the job.

Can I plug a tesla directly into an outlet?

Absolutely. Your home wall outlets provide around 110/120 V at 15/30 A. This range will initiate trickle charging and your car will be charged over a long time. The charging rate will be slow but steady.

Can you plug a tesla directly into an outlet

On the flip side, the larger outlet of your garage will provide a larger 240 V AC output at 30 or 60 A. This will make the chagrin process much faster. You may need to use a power adopter in case the connector has any type of connection issue.

How much does it cost to charge a tesla?

Around 3.5-4 cents per mile. Charging your Tesla is essentially your mileage. Instead of relying on the litter per mile basis, Tesla owners have shifted into the money per mile basis.

Let’s assume you have a 75kWh battery pack with a 310-mile range. If you can achieve an average charging efficiency of 85%, It’ll cost you $11.47 to charge your Tesla completely; assuming the average national electric pricing of 13 cents per kWh.

How much does it cost to charge a tesla

In case you’re using a generator at 15A with 110 or 120 V power output. Each gallon of gasoline can put roughly 20-22 miles equivalent of charge into your system. This may cost you way over 5 cents for each mile.

How do you check the output of a generator?

The maximum output a generator can produce is usually displayed over its body and the user manual. There will be some stickers on your generator’s body showing the maximum power it can produce. We recommend that you use a generator that can produce at least  6500 Watts or more.

How do you check the output of a generator

In case you fail to measure the output, you can use a voltmeter. If you don’t want to blow up the fuse of your voltmeter, don’t forget to ground your voltmeter and turn the selector to the “AC Voltage” option.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

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