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Comment by masklinn | Hacker News Reader

Afaik that’s pure series hybrid and that’s almost non-existent in cars (outside of range extenders, not that there are that many of those).

There are a handful but most hybrids are either parallel or series-parallel. I assume because the power range is so low that the conversion losses are way too noticeable compared to a mechanical drivetrain.

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No, the entire point of a series-parallel hybrid is that it can offer the advantage of a series hybrid.

The Toyota Prius powerchain has two motor generators, and can take part of the ICE power from one and transfer it electrically to the other, remapping the engine RPM into more efficient power bands at the same time. It has a mode that can do this even when no power is being used from the battery.

It’s kind of a best of both worlds. They can avoid the extra weight of a full series hybrid, because they don’t need a motor generator pair that handles the full engine power.

Actually, power bands remapping is essential for the Prius to operate.

There is no clutch, there is no neutral gear, there is no torque converter. The ICE is always connected directly to the wheels with a fixed gear ratio on a planetary gear set. (Which improves transmission efficiency over a automatic/CVT gearbox, and actually reduces maintenance costs)

One of the motor-generators is on the 3rd input of the planetary gear. For the ICE to idle (during warm up, or when you have the heater on), the motor-generator much be spinning backwards at the exact same speed so that the wheels stay stationary.

Power band remapping can also be used for reversing when the battery is empty.

Current Honda hybrids are like that. The only time the Internal Combustion Engine (ICE) is directly connected to the drive train is when the speed gets to above around 60MPH. The rest of the time the ICE is used to power a generator which then sends power to the electric motor and/or the battery pack.

https://www.youtube.com/watch?v=QLUIExAnNcE has more info.

That's something I wish there had been more focus on, instead of focusing on massive heavy batteries, develop the hybrids further.

Not sure about the US, but the Japanese didn't stop focusing on hybrid development. More than half of all sales in Japan are hybrids, whereas electric is only a few percent [1].

Honda even recently announced that they're scaling back on electric to focus on hybrids:

https://www.reuters.com/business/autos-transportation/japans...

[1] https://www.bloomberg.com/news/articles/2023-12-19/hybrid-ca...

Yes but Honda seems to be doing this because they can’t make batteries. BYD can, ever cheaper, and they’re expanding their plug-in offerings much faster than Honda is scaling them back. I’m worried for Japanese car makers.

Yep. Hybrids are a dead end, they’ll be obsolete in a few short years

But series-parallel has the very same advantage - can keep the RPM in sweet spot.

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