Why your EV’s voltage matters, and what it means for your ca…

GM Ultium EV Platform
General Motors

Electric cars are slowly but surely becoming commonplace, and they offer a whole new generation of features that deserve attention. Range is an obvious one – but there’s another metric that has a big impact on the overall experience of owning an electric car: voltage.

You’ll often see commercials discussing the voltage of an electric car’s battery pack. For example, Hyundai is proud of the 800-volt batteries in cars like the EV6 – which is twice the voltage of the 400V battery in the Tesla Model Y.

But what does that actually mean? Here’s everything you need to know.

electricity 101

When you plug the charger into your electric car, electricity flows from the charger to your car’s battery. You can measure this flow in watts, volts, and amps, which each represent a different aspect of the phenomenon. But the concept of voltage is relatively easy to understand.

Think of electricity like water and voltage like water pressure. In this case the voltage is the amount of pressure applied in the pipe. Higher pressure pushes water through the pipes faster. The higher the voltage in the charging setup, the more energy will flow using less current.

white tesla on a supercharger

The water analogy continues. In this case the amps (or current) are equal to the size of the pipe. If you want to move a ton of water, you can either increase the pressure, or make the pipe larger. Electricity also works in the same way. Charging speed mostly depends on voltage and current. With higher voltage, less current is required – and with lower voltage, higher current is required.

This is where watts come in, as these are an expression of overall power: to calculate watts, you simply multiply the system’s voltage by the amperage. For example, take 120 volts at 1 amp, and you have 120 watts. That number represents a snapshot of the power being transferred at any given time, but your EV’s battery is measured in watt hours – that’s how we measure capacity. Kilowatt hour (kWh) refers to the electricity that can be supplied over a period of one hour. If your car has a 100kWh battery, it is capable of supplying 100kW (100,000 watts) of power for one hour.

what does high voltage mean

head spinning? Don’t worry, learning all the new words is over. Bottom line: Faster charging requires more voltage or more current. However, increasing the current results in greater energy loss and heat – which actually makes it more difficult to charge faster. Thus, the better way to actually charge faster is to increase the pressure inside that pump – with higher voltage.

Front view of the red Hyundai Ioniq 6.
Christian De Looper /

The fact that higher current brings more heat and energy loss means that higher-voltage cars can conserve power better, reducing energy consumption. High-voltage batteries can not only provide more power, but more of that power will actually be used by the motor. And, because less energy is lost as heat, the battery is better preserved.

So why don’t all EVs use high-voltage systems?

Challenges of increasing voltage

Implementing a truly high-voltage system means that car manufacturers must redesign the circuits and components inside the car to ensure that the systems are safe and reliable in high-voltage environments.

Two electrified US charging stations.
electrify america

That in itself can be expensive. But in addition to redesigning the car’s electrical system, the components that make up that system also become more expensive. So it’s not surprising why not every car uses 800V batteries, the answer is simple: money.

Which cars are already 800V?

In today’s world, a high-voltage system essentially means an 800V system – although it’s possible we’ll go even higher than that. Lucid, which holds the records for both range and charging speed, already uses a 900V battery pack.

Some of the most notable 800V cars are the Kia EV6, Hyundai Ioniq 5, and Hyundai Ioniq 6, which not only use higher-voltage systems, but also come at a reasonable price – for EVs, anyway. These cars can charge at 350kW, which is the fastest EV charging speed widely available at the moment.

Other car companies that have adopted high-voltage systems include the likes of Porsche and Audi, and they also offer cars that can use the full 350kW charging speed.

There’s likely more to come on the way. The Kia EV9, coming very soon, offers an 800V architecture, however, Kia has announced that some of its upcoming low-cost cars will use a 400V architecture instead. Hopefully, 400V EVs will become a thing of the past in the next five years.

But… my car charges at 350kW and is 400V

Then you must have something like the Hummer EV. there are Some? Cars that run on a 400V architecture can still use the maximum 350kW charging speed available, a charging speed typically reserved for 800V cars.

Hummer EV

In the case of the Hummer EV, this is achieved through the use of a dual-layer battery, with each layer capable of charging semi-independently.

There aren’t many other cars that use these kinds of devices, and eventually, it’s likely that manufacturers will move away from these types of devices in favor of full 800V architectures, at least over time.

There are obvious benefits to 800V cars, however, it may take some time Everyone Uses them. Hopefully, this will happen sooner rather than later – especially given the fact that high EV charging speeds are so important.

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