Hybrid Vehicle Drivetrain Comparison (Series vs Parallel)

(Updated on September 21, 2021)

There are a lot of different hybrid models available on the market. Some are plug-in hybrids which need an outlet to get recharged while others are basic hybrids which utilize more gasoline power instead. Aside from there being different types of hybrids, there are also different types of drivetrains for them as well. There are series/parallel drivetrains, series drivetrains, and parallel drivetrains. In hybrids which have no internal combustion engine whatsoever, such as hydrogen fuel cell vehicles and battery/electric vehicles, they require various drivetrain assemblies to function. You will learn more about these drivetrains below.

Related: FWD vs RWD vs AWD vs 4WD

Series Drivetrains

You will see series drivetrains in a lot of standard hybrid vehicles. With a series drivetrain configuration, the wheels get their power solely from the electric motor. To make this happen, electric power is supplied to the motor from a generator or battery pack. The gasoline engine in the vehicle is what gives power to the generator which, in turn, gives power to the electric motor. Not only that, the battery pack will also be recharged by the generator too. It is also common for series drivetrain vehicles to have what is called regenerative braking. Each time you step on the brake pedal with this braking system, it will cause the battery pack to receive a small recharge. A series drivetrain hybrid vehicle is more suitable for stop-and-go traffic.

Read also: Top 5 of Mercedes Benz Hybrid Cars

Parallel Drivetrains

If your hybrid vehicle has a parallel drivetrain, the wheels will get their power from both the electric motor and the gasoline engine. The battery pack in a parallel drivetrain is smaller than the one you’d find in a series drivetrain. Automakers have designed parallel drivetrains so that their battery packs depend more on regenerative braking in order to be recharged. If the battery pack still needs more power because there is an inadequate amount of regenerative braking taking place, the electric motor will supplement the power needed to recharge the battery. This is similar to how an alternator works in regular vehicles. You will find a hybrid parallel drivetrain more beneficial on faster roads like the interstate. This is due to its incredible efficiency when mechanical power gets converted into electrical power.

Series/Parallel Drivetrains

Some hybrid vehicles, like the Toyota Prius, have combined the series drivetrain and parallel drivetrain into one unique drivetrain. It basically takes the advantages of each drivetrain and places them together. When you are driving throughout your town or city, you will have the advantages of a series drivetrain. If you are driving on the highway, the benefits of the parallel drivetrain will kick in. This allows the engine’s performance to remain efficient on most roads.

Of course, you can expect a series/parallel drivetrain to be more expensive to purchase and manage. It features a big battery pack, generator, and it requires a lot of computing power in order to operate both drivetrain systems. If you don’t mind the extra cost then you will have a hybrid which performs better, has more fuel efficiency, and works great anywhere.

2 thoughts on “Hybrid Vehicle Drivetrain Comparison (Series vs Parallel)”

  1. “If the battery pack still needs more power because there is an inadequate amount of regenerative braking taking place, the electric motor will supplement the power needed to recharge the battery.”
    So the battery charges itself?

    Reply
    • Well, not quite. In some vehicles, regenerative braking is used to charge the battery. The vehicle uses the kinetic energy of its rotating wheels as a sort of “generator” (much like an alternator). That kinetic energy is converted to potential energy that is then stored in the battery. This has the added benefit of slowing the car, so this is commonly used in hybrid and EV braking systems.

      Hybrids have the added benefit of an onboard combustion engine. Its fuel is usually gasoline or diesel, not electricity. Some hybrids are built to use the battery pack to power the vehicle, and the combustion engine just acts as a generator to replace the battery’s charge while you drive.

      This sort of hybrid setup usually nets the driver with most of the benefits of an EV powertrain (instant torque, extremely low emissions) with the range you would expect from a typical gasoline or diesel engine.

      Reply

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