# Are there any electric car designs that use a generator engine to charge the battery? **URL:** \ **Category:** Factual Questions\ **Created:** [January 4, 2022, 6:59pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213 "2022-01-04T18:59:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [January 4, 2022, 6:59pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/1 "2022-01-04T18:59:54Z")
I’ve always thought a transitional electric vehicle model would have something like a 40-60 mile range, but with a backup gas generator (not car engine) that recharged the batteries to extend the range when needed. So you might think “well if you’re going to have a gas generator, why not just keep an engine in the car and make it a hybrid?” Several reasons: a car engine has to be useful at a large range of RPM and variable torque requirements, which makes it bigger, heavier, and less efficient at doing any one thing It has to be connected to the rest of the car through a mechanical transmission which adds weight/maintenance/failure points whereas a gasoline generator that just charges the battery can be smaller, specialized, be designed for one purpose: to charge the battery, run at a specific RPM, gaining fuel efficiency, and since it only charges the batteries, it doesn’t add much in the way of mechanically complex systems to the car. It’s basically a specialty device on an otherwise all-electric car that extends your battery range for the occasions where you need that. I always thought this would be a good compromise model for transitioning to EVs while still getting almost all of the benefits of getting rid of gas engines. But I haven’t actually seen any cars that seem to use this model that I’m aware of. Are there models that use this style of drive? Is there a name for the design? Or is there something impractical about it? ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [January 4, 2022, 7:04pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/2 "2022-01-04T19:04:23Z")
Do you mean a [range extender](https://en.wikipedia.org/wiki/Range_extender)? ---
**Author:** ![Doubticus2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doubticus2/32/9886_2.png) [@Doubticus2](https://boards.straightdope.com/u/Doubticus2)\ **Post date:** [January 4, 2022, 7:05pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/3 "2022-01-04T19:05:16Z")
I own two, but they are now discontinued. > **[Chevrolet Volt](https://en.wikipedia.org/wiki/Chevrolet_Volt)** > > Pages for logged out editors learn more > > > > The Chevrolet Volt is a plug-in hybrid manufactured by General Motors, also marketed in rebadged variants as the Holden Volt in Australia and New Zealand and the Buick Velite 5 in China, and with a different fascia as the Vauxhall Ampera in the United Kingdom and as the Opel Ampera in the remainder of Europe. Volt production ended in February 2019. > Sales of the 2011 Volt began in the United States in mid-December 2010, followed by various Euro... ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [January 4, 2022, 7:05pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/4 "2022-01-04T19:05:51Z")
Well, basically yes, but integral to the vehicle - a small generator packed away somewhere, rather than something you would attach. Edit: Reading further, I guess that is exactly what I mean, and apparently it is used in a few cars, most notably the Volt. ---
**Author:** ![tofor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tofor/32/13727_2.png) [@tofor](https://boards.straightdope.com/u/tofor)\ **Post date:** [January 4, 2022, 7:07pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/5 "2022-01-04T19:07:26Z")
I…actually thought that’s how all hybrid vehicles worked. I must have read about the Volt and inadvertently extended that to all hybrids? Why isn’t everybody doing this? ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [January 4, 2022, 7:07pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/6 "2022-01-04T19:07:31Z")
The [BMW i3](https://en.wikipedia.org/wiki/BMW_i3) did have that as an [option](https://en.wikipedia.org/wiki/BMW_i3#Range_extender_option). ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [January 4, 2022, 7:07pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/7 "2022-01-04T19:07:49Z")
> [@SenorBeef](#): > > Is there a name for the design? The term you are looking for may be “series hybrid” where only the electric motor drives the wheels. As opposed to “parallel hybrid.” ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [January 4, 2022, 7:14pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/8 "2022-01-04T19:14:39Z")
> [@Doubticus2](#): > > I own two, but they are now discontinued. > > [Chevrolet Volt - Wikipedia](https://en.wikipedia.org/wiki/Chevrolet_Volt) Technically the Chevrolet Volt isn’t a pure series hybrid because there is a mechanical link to the wheels that can kick in at higher speeds. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [January 4, 2022, 7:17pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/9 "2022-01-04T19:17:04Z")
> [@tofor](#): > > I…actually thought that’s how all hybrid vehicles worked. I must have read about the Volt and inadvertently extended that to all hybrids? The traditional hybrid model uses the gasoline engine for most of its power. It uses regenerative breaking to recoup some of the lost energy you’d lose to breaking, but otherwise are primarily gasoline driven vehicles - just with added efficiency from regenerative braking. The batteries are only big enough to store enough energy to get the car back up to speed - maybe a few times. It’s a buffer rather than a primary power source. Plug-in hybrids add bigger batteries (something like 20-40 mile capacity) so you can charge them up so they’re closer to being true hybrids, but the still have a traditional engine and mechanical transmission so the car can have indefinite range on gasoline. Electric vehicles weren’t really ready for primetime when the first hybrids like the Prius were finding ways to make traditional cars more efficient. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [January 4, 2022, 7:27pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/10 "2022-01-04T19:27:58Z")
This seems so obvious that it would be the way to go, that I’m sure there are reasons that car companies don’t do it that way. I guess, for unlimited range, you would need a gasoline engine large enough to keep the car going at around 80 MPH or something, so maybe once you get to an engine that size, you may as well have it directly driving the wheels? I think that diesel train engines and some large earth movers use an engine to power an electric motor which powers the wheels. ---
**Author:** ![sitchensis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sitchensis/32/4892_2.png) [@sitchensis](https://boards.straightdope.com/u/sitchensis)\ **Post date:** [January 4, 2022, 7:29pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/11 "2022-01-04T19:29:40Z")
A few trucking companies are looking at it for semi trucks. Similar to train technology. Using a high efficiency diesel engine to charge batteries/run electric motors. ---
**Author:** ![Heracles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heracles/32/487_2.png) [@Heracles](https://boards.straightdope.com/u/Heracles)\ **Post date:** [January 4, 2022, 7:30pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/12 "2022-01-04T19:30:19Z")
The BMW i3 REX was exactly as the OP described: a pure electric drivetrain with a small gasoline-powered generator that kicked in to generate electricity once the battery was near empty. As I understand it, the generator was based on a BMW motorcycle engine. This was not quite sufficient to keep the vehicle moving at highway speeds, uphill, with a full load, once the battery was empty; and when it couldn’t keep up, the car slowed to a crawl very suddenly. There were lawsuits. See [previous thread on this subject](https://boards.straightdope.com/t/series-hybrids-they-make-paper-sense-why-arent-they-more-common/787808) (2017). ETA: In general, at stable highway speeds, it makes more sense energy-wise for the gasoline engine / generator to drive the wheels directly (like a Chevy Volt). But this doesn’t scale well to a larger car, and people in North America want trucks, so GM stopped offering the Volt. It’s a pity, because a concept like the Volt is exactly what’s needed to fight range anxiety. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [January 4, 2022, 7:46pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/13 "2022-01-04T19:46:26Z")
> [@Heracles](#): > > and when it couldn’t keep up, the car slowed to a crawl very suddenly Slightly OT: My sister had a BMW diesel 3 series and it would also slow to a crawl when anything seemed off in that engine. Seems like something BMW likes to do to their drivers. ---
**Author:** ![Doubticus2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doubticus2/32/9886_2.png) [@Doubticus2](https://boards.straightdope.com/u/Doubticus2)\ **Post date:** [January 4, 2022, 7:57pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/14 "2022-01-04T19:57:32Z")
True, but I bought one tank of gas all of last year. ---
**Author:** ![Folly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/folly/32/3219_2.png) [@Folly](https://boards.straightdope.com/u/Folly)\ **Post date:** [January 4, 2022, 8:00pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/15 "2022-01-04T20:00:03Z")
I didn’t mean to imply it’s necessarily a bad thing. Especially if it solves the problem BMW seemed to have. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [January 4, 2022, 8:02pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/16 "2022-01-04T20:02:47Z")
> [@Heracles](#): > > ETA: In general, at stable highway speeds, it makes more sense energy-wise for the gasoline engine / generator to drive the wheels directly (like a Chevy Volt). But this doesn’t scale well to a larger car, and people in North America want trucks, so GM stopped offering the Volt. It’s a pity, because a concept like the Volt is exactly what’s needed to fight range anxiety. I read someplace that the reason they stopped selling the Volt was that it’s a sedan and people just don’t want them any longer. ---
**Author:** ![jjakucyk](https://avatars.discourse-cdn.com/v4/letter/j/3d9bf3/32.png) [@jjakucyk](https://boards.straightdope.com/u/jjakucyk)\ **Post date:** [January 4, 2022, 8:15pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/17 "2022-01-04T20:15:20Z")
> [@Dewey\_Finn](#): > > I read someplace that the reason they stopped selling the Volt was that it’s a sedan and people just don’t want them any longer. I hate this line of reasoning because the automakers are making it self-fulfilling by only offering lame cars in lower trim levels and generally weaker drive trains. “You can pick between this econobox we don’t actually want to sell because our profit margins on it are too low, and this SUV or monster truck with all the trimmings. By the way have you talked to our financing department?” I wish gas would just go back up to $5/gallon so we can stop this nonsense. > [@RitterSport](#): > > I think that diesel train engines and some large earth movers use an engine to power an electric motor which powers the wheels. That’s mainly because at such high power levels there just isn’t a mechanical transmission that can handle the load efficiently and/or reliably. It also allows the actual drive train (heh) to be basically the same between diesel/electric locomotives and all electric locomotives, which has some design and economy of scale benefits. ---
**Author:** ![RitterSport](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rittersport/32/6326_2.png) [@RitterSport](https://boards.straightdope.com/u/RitterSport)\ **Post date:** [January 4, 2022, 8:16pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/18 "2022-01-04T20:16:28Z")
Interesting. Thanks! ---
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [January 4, 2022, 8:47pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/19 "2022-01-04T20:47:12Z")
> [@RitterSport](#): > > This seems so obvious that it would be the way to go, that I’m sure there are reasons that car companies don’t do it that way. I think it’s mostly that plug-in hybrids and EVs with a range extender have many of the disadvantages of _both_ ICE and EV cars. High maintenance engines, limited electric range, still need gas, still need to plug them in to get the advantages of an EV. The added complexity makes them expensive, so they’re small cars that aren’t competitive on price with full ICE (or traditional hybrid) small cars. Probably the best known range extended car is the BMW i3, with the optional two-cylinder engine (REx). In order to qualify as an EV in the US, the REx could only come on when the battery was very depleted, limiting the usefulness of the REx. If you are depleting the battery faster than the REx can keep up, then you’re going to have to stop. In other markets (and in hacked US cars) the i3 can enable the REx at higher states of charge, so that there is more opportunity to make a net gain in charge. Here is a bit of a table from [Bureau of Transportation Statistics](https://www.bts.gov/content/gasoline-hybrid-and-electric-vehicle-sales) showing sales of the three classes of electric vehicles. The PHEV entries “include plug-in hybrid and extended range EVs.” What it shows to me is that maybe PHEVs were starting to take off, and then in 2018 the Tesla Model 3 came along and ate their sales. Traditional hybrids are still going strong. | | (R) 2015 | (R) 2016 | (R) 2017 | (R) 2018 | (R) 2019 | 2020 | | --- | --- | --- | --- | --- | --- | --- | | Hybrid | 384,400 | 346,949 | 362,868 | 338,083 | 380,794 | 454,890 | | PHEV | 42,959 | 72,885 | 91,188 | 123,883 | 85,791 | 66,157 | | EV | 71,064 | 86,731 | 104,487 | 207,062 | 233,822 | 240,053 | ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [January 4, 2022, 8:56pm UTC](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213/20 "2022-01-04T20:56:50Z")
Yes, the BMW I3 came to mind when I saw this question. If the engine cannot run the vehicle all the time, if the vehicle can still deplete the battery and then must stop, what’s the point? Use the weight allowance for extra battery instead. I guess the question would be - can you fire up the range extender while the vehicle is parked? Can you use an app to remotely begin charging? (Both useless options anyway if the vehicle is inside a closed garage; plus it might alarm passers-by to see a vehicle running while parked and empty.) [Next page](https://boards.straightdope.com/t/are-there-any-electric-car-designs-that-use-a-generator-engine-to-charge-the-battery/957213.md?page=2)