Germans create ‘free-piston’ multi-fuel engine that could answer EV range-anxiety issues

By Nick Jaynes March 17, 2013

piston-free generator — Image used with permission by copyright holder

The Germans never cease to amaze us.

A group of scientists at the German Aerospace Center (DLR) have developed what they called the “free-piston linear generator” or, in German, the “Freikolbenlineargenerator.”

In distinctly German form, the name is an entire sentence squished into a single word and not a satirical joke as we had hoped. The ingenious electricity generator is small, lightweight, and ideal for a range-extending application in an electric vehicle – and who knows what else.

piston-free generator close up — Image used with permission by copyright holder

Comprised of two pistons inside a single cylinder facing one another, the pistons are fired simultaneously; the kinetic energy of the combustion is used to generate electricity. The opposing boxer-type movement of the pistons also means the engine offsets much of its own vibration for smooth operation.

More tech details and a concept video (in German) are here

In place of a traditional crankshaft and connecting rod, there is a gas spring behind each piston. This gas spring can be used to adjust the compression ratio on the fly. The ratio and combustion chamber size can be adjusted so minutely as to accommodate movements down to one tenth of a millimeter. This allows the piston-free generator to run anything from gasoline to diesel to natural gas to hydrogen.

piston-free generator in car — Image used with permission by copyright holder

This sort of flexible electricity generation makes the free-piston generator perfect for electric cars that require a range-extending onboard generator. The Chevrolet Volt, for example, has a 1.4-liter inline four-cylinder gasoline generator that fires up after the initial 38-mile all-electric range is depleted.

Right now the free-piston generator only exists on a bench in Germany but we wouldn’t be at all surprised if some big-name automaker jumps all over this technology as it could be a small, lightweight solution to many EV problems.

We’ve always joked that the Germans were magic. With the unveiling of this “free-piston” generator, we now know they are.

Topics

Former Digital Trends Contributor

Nick Jaynes is the Automotive Editor for Digital Trends. He developed a passion for writing about cars working his way…

Cars

Rivian R2 vs Hyundai Ioniq 5: Should you wait for the Rivian R2?

Rivian R2

Rivian has taken the wraps off of the Rivian R2, an electric SUV that's similar to the much-loved R1S, but smaller and, crucially, cheaper. But the R2 goes up against some serious competition. The likes of Hyundai have been building solid EVs for some time now -- including the Hyundai Ioniq 5.

The R2 and the Ioniq 5 each make a compelling case for themselves, and they're likely to end up being similarly priced if the Ioniq 5 doesn't get much cheaper and the R2 does end up being sold at $45,000. To be fair, the cars are pretty different -- the R2 is more of an SUV, while the Ioniq 5 is much more crossover-sized. But because of their similar price, you might be deciding between the two. How do they compare? We put the Rivian R2 and the Hyundai Ioniq 5 head-to-head.
Design
The differences between the Rivian R2 and the Hyundai Ioniq 5 are perhaps no more apparent than when it comes to design.

Cars

The 6 best remote car starters in 2024

Best car remote starters

While some modern vehicles come standard with remote start features, it's still relatively uncommon. That's a shame because if you live somewhere where cold weather, snow, and ice are frequent concerns, a remote car starter is one of the best auto accessories you can have. If you're not familiar with them, a remote car starter works similarly to a key fob, except it will actually start your car from a distance instead of just unlocking the doors or trunk. That means you can start your car from the warm comfort of your home or office before venturing out. If you live somewhere hot, you can even start your car and let the AC run for a little bit. You'll never enter a freezing cold or scorching hot vehicle again.

The best remote car starters have long ranges, replaceable batteries, and other handy features — but how do you know which is best for you? We’ve compiled a list of the best car starters in a range of prices and features. Keep in mind that while you can install some yourself, some will require a professional.
The best remote car starters in 2024

Cars

The best portable jump starters for cars in 2024

The Clore Jump-N-Carry JNC660 portable jump starter connected to a truck battery.

Any time you hit the road, whether you're taking a short or long trip, it's a good idea to have backups handy. A spare or backup tire, some anti-freeze, windshield wash fluid, a road hazard kit, and, last but not least, one of the best portable tire inflators and a portable jump starter. You never know when cold weather, inadvertently leaving the dome light on, or plain old Father Time can curse you with a dead battery. Ensure you have one of the best portable jump starters that can save you in a jam, kickstarting your car even when there isn't anyone around to jump the battery. Naturally, that's why we’ve rounded up what we feel are the best portable jump starters for 2024.
The best portable jump starters in 2024

Buy the if you want the best portable jump starter overall.
Buy the if you want the best portable jump starter runner-up.
Buy the if you want the best portable jump starter and tire inflator combo.
Buy the if you want another name-brand option.
Buy the if you want the best portable jump starter for cheap.