Do Teslas Have Alternators? Why Don’t They Add One?

Are you wondering “Do Teslas have alternators?” Perhaps you’re considering why they don’t just add one to make charging stations moot? Well, let’s chat about it and make it easy to understand.

Key Takeaways:

While most tires on fossil fuel vehicles last an average of 50k-60k miles (about 4 years), tires on electric vehicles don’t last nearly as long and you may need to change them as soon as 15-20K miles.
As a general rule, you should start shopping for new tires one the tread pattern has about 4/32″ of an inch remaining.
While many tires are warranted between 45k-60k miles, electric vehicles like Teslas wear out much faster, meaning replacement can come as soon as 15k miles.

Electric vehicles like Teslas do not contain alternators because they don’t need them.

Instead, they use a DC-to-DC converter to send power to a 12-volt battery (i.e., a smaller one) to start the engine and power electrical components when the main battery is turned off.

Essentially, the DC-to-DC converter acts as the alternator. But you must recharge the battery instead of using fuel to generate power. 

While a self-charging Tesla would remove the necessity for charging stations and do away with range anxiety, it isn’t quite as simple as that. And this article explains why.

Do Teslas Have Alternators?

While some people believe Teslas have alternators because they boast regenerative braking, this isn’t the case. Electric cars don’t need alternators!

Teslas have a 12-volt starter battery which is charged by a DC-to-DC converter.

The latter turns the 400-volt DC from the traction battery into 14.4 volts or thereabouts to power the starter battery and electrical devices like the radio and lights. 

The aforementioned regenerative braking system does recover some energy of motion and turns it into electricity, resulting in traction battery charging.

So, in this sense, the DC-to-DC converter works like an alternator. However, it uses the vehicle’s kinetic energy, causing it to slow down instead of providing self-charging capabilities.

Naturally, this is preferable to friction brakes that quickly heat up, wear out, and let the car’s energy contribute to the excessive damage to the brake discs and pads!

nikoli Tesla patent on alternators 1891
The original patent design from Nikoli Tesla in 1891, credit:

Alternators Aren’t Free Energy

Before we take a peek at why Tesla isn’t rushing to add alternators to their vehicles, it’s worth understanding that they aren’t a source of free energy — yes, even on an ICE car. 

Alternators use up to 1HP from the engine to generate electricity, and this can change depending on the load.

The amount of power gained (around 0.75kw) isn’t enough to get an electric vehicle moving, let alone driving around at 30 miles per hour. For context, that requires roughly 20kw of power.

Why Don’t Tesla Add Alternators to Their Vehicles?

Adding an alternator to a Tesla seems ideal. Who doesn’t want a self-charging electric vehicle, after all?

But as we briefly touched upon, it’s not as simple as just integrating an alternator in an EV engine.

There are two main reasons why electric cars like Tesla don’t have alternators:

  1. They don’t generate power from thin air — Alternators in gas cars form electricity from mechanical power supplied by burning fuel when running the engine. Since electric vehicles don’t have gas engines, the alternator would lack a source of power.
  2. They would use more energy than they would make — While Tesla could make their electric car’s rechargeable battery spin the alternator, it would be a self-defeating act. Why? Because the alternator would use up more electricity than it would create!

Installing a big alternator in an EV engine would give you less range than current systems. If this sounds surprising to you, consider this: no machine is 100% efficient. 

In gas cars, the engine is actually burning more fuel to allow the alternator to run. However, it’s purely out of necessity to run the ignition and other electrical systems. 

Electric vehicles can use anywhere between 500 and 2000 amps, meaning you’d need an almost-standard-sized gasoline engine to run a big enough alternator. At this point, you’ve got yourself a hybrid!

Let’s Look at an Example

Any machine loses energy in some way while they’re working. And without an onboard store of energy (i.e., fuel, batteries, or similar), it’ll need supplying from an external source. 

Let’s look at an example to give you a more illustrative understanding of this sort of energy expenditure. We’ll use an EV’s battery and arbitrary numbers to explain the process. 

Your vehicle is traveling at a steady pace along a flat road. Doing this causes it to draw a constant ten units of power from the battery. 

That ten units is then lost to the car. Some of it turns into heat as mechanical and electrical components warm up, and friction generates between the tires and the road surface. The rest is used to battle air resistance and road noise. The energy has left the vehicle’s system no matter where it goes. 

So, you decide to harness this otherwise-lost power by strapping an alternator to the vehicle and using the wheels’ turning motion to charge it.

Amazingly, you find one that’s completely efficient. In other words, it puts out as much electricity as it takes in mechanical energy.

You aim to put ten units of electrical power back into the battery, so you attach your alternator, and nothing changes. The battery drains just the same as without your supposed cure-all. 

While you may think this is a mistake, it isn’t. 

A 100% efficient alternator like the one used in this example needs a constant ten energy units to steadily provide ten units.

The vehicle’s motors would offer this from the battery, meaning it’s providing 20 units to power the vehicle and the alternator. But since it’s feeding ten straight back into the battery, the drain rate remains the same.

Therefore, attaching an alternator to a Tesla is worse than pointless. Their regenerative braking system (which still isn’t free energy, as we explained earlier) is as good as it currently gets. 

Is The Future Filled with Self-Charging Teslas?

Despite everything, some people speculate that Teslas and other EVs may one day be self-charging, using energy from the sun or some futuristic dynamic roadway charging contraption. 

If that is the case, you’ll be able to travel massive distances without stopping. But this is a long way off!

Final Thoughts

While self-charging Teslas might be the dream, they don’t exist yet.

EVs like Teslas don’t have alternators because they don’t need them. Instead, DC-to-DC converters transfer energy to the smaller starter battery, acting as a sort-of alternator in their own way.