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08-28-2017, 02:24 PM | #1 | |
Moderator Join Date: Sep 2008 Location: PA
Posts: 13,935
| Why Don't Electric Cars Have Multi-Gear Transmissions?
People on this site often ask about 2-speed transmissions in their RC vehicle. Most often people tell them to avoid the extra complexity and weight and stick with a single speed. This is a good read. It's about 1:1 vehicles, but it would be applicable to RC as well. Quote:
Source: Why Don't Electric Cars Have Multi-Gear Transmissions? | |
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08-28-2017, 04:01 PM | #2 |
Pebble Pounder Join Date: Jul 2013 Location: El Centro
Posts: 146
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
I don't know about other people on this site, but I think 2 speed transmissions still hold value to some in the RC crawling world. Trailing is a good example of it, where you might want the taller gear to avoid having to hold throttle wide open on flat parts of the trail, whereas the lower speed gives you more finesse over the rough, rocky parts of the trail. Is it ideal for everyone - no - but I have seen people use it and like it on their trail rigs. I personally don't use 2 speed transmissions, but I see the appeal. -Corrupt |
08-28-2017, 06:37 PM | #3 |
I wanna be Dave Join Date: Sep 2011 Location: Douglassville, PA
Posts: 4,224
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
I run several rigs with a 2 speed - your reasoning is spot on. Plus, it's fun to shift - adds a dynamic element to driving. |
08-28-2017, 09:07 PM | #4 |
Quarry Creeper Join Date: Aug 2016 Location: British Columbia
Posts: 466
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
If you have high enough motor rpms, and high enough voltage batteries, you can get away without shifitng gears in an ev - but, as detailed in the video, there are advantages to multi-gear transmissions. Tesla tried to put two-speeds in their earlier cars. https://www.autoblog.com/2008/01/23/...sion-woes-get/ Fortunately, the axial 2-speed transmissions have proven to be reliable. And we may see more of them in 1:1 EVs. "Gasoline cars currently have something electrics don't: a [multi-gear] gearbox. This may be about to change though, as the advantage of having a choice of gears is simply too great for electric carmakers to ignore." Multi-Speed Gearboxes Are Coming to EVs | PluginCars.com ZF: Multi-Speed Transmissions Coming Soon For Electric Cars |
08-29-2017, 06:25 AM | #5 |
Moderator Join Date: Sep 2008 Location: PA
Posts: 13,935
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? |
08-29-2017, 06:59 AM | #6 |
RCC Addict Join Date: May 2015 Location: Price Twp.
Posts: 1,291
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? |
08-29-2017, 07:55 AM | #7 |
Quarry Creeper Join Date: Nov 2005 Location: Western, NC
Posts: 490
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
I have the AX2 two speed in my Wraith and really like it. The only downside is the cost of replacement parts for it. If you have a high HP setup, it chews up the internal gears much faster than I think it should, and the early ones had isses snapping some of the gear shafts as well.
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08-29-2017, 02:18 PM | #8 |
I wanna be Dave Join Date: Sep 2011 Location: Douglassville, PA
Posts: 4,224
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
If you have a high HP setup, you don't really need a 2 speed. Although shifting is fun... I run 2S on all my rigs, so the 2 speed gives great low end torque, and then wheelspeed when needed. For the most part, I run in low over obstacles and in technical sections, then shift into high for cruising along the trail, usually at 1/3 throttle or so. Saves a ton of battery. I would think the same principle would work in a 1:1. Torque needs at highway speeds are far less than when accelerating. A simple transmission of some kind makes sense. |
08-29-2017, 02:26 PM | #9 |
MODERATOR™ Join Date: Jul 2004 Location: Ohio
Posts: 18,928
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
A CVT type to keep it at peak efficiency. I win.
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08-29-2017, 02:30 PM | #10 |
Quarry Creeper Join Date: Oct 2012 Location: Oregon
Posts: 371
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
Any motor/engine will have an area in their power curve where their output is most efficient, gearboxes are designed to try to keep the power plant running in this efficient area to maximize their fuel/electricity and keep things from overheating.
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08-29-2017, 02:35 PM | #11 |
MODERATOR™ Join Date: Jul 2004 Location: Ohio
Posts: 18,928
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
Yes and a CVT will keep it at that exact number RPM whilst a multi geared transmission cannot. They're trying to though with these recent 8 speeds. Trying to be all Formula 1 like.
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08-30-2017, 09:56 AM | #12 |
Moderator Join Date: Sep 2008 Location: PA
Posts: 13,935
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
CVTs are relatively weak and inefficient.
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08-30-2017, 10:37 AM | #13 |
Quarry Creeper Join Date: Nov 2005 Location: Western, NC
Posts: 490
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? Weak and inefficient how? I have seen zero data to back this up. Matter of fact, CVT equipped cars almost always post higher average MPG than thier manual transmission equipped counterpart. Unless you're talking about high HP applications, of which there are clearly better designed transmissions out there for that job. Last edited by hpiguy; 08-30-2017 at 10:45 AM. |
08-30-2017, 10:46 AM | #14 | |
Moderator Join Date: Sep 2008 Location: PA
Posts: 13,935
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? Quote:
Nissan uses CVTs in some of their vehicles. But CVTs aren't as efficient as manual transmissions. | |
08-30-2017, 10:54 AM | #15 |
MODERATOR™ Join Date: Jul 2004 Location: Ohio
Posts: 18,928
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? |
08-30-2017, 10:56 AM | #16 |
Quarry Creeper Join Date: Nov 2005 Location: Western, NC
Posts: 490
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
Neither are automatics, or DSG or anything else, and they never will be as efficient as a manual transmission from a pure engineering standpoint. The CVT was never designed for go fast stuff, quite the contrary. Lots of manufacturers use them with varying success these days. If you haven't driven a new car with a well designed CVT, they've came a long way since Nissan started using them 10 or so years ago. For the record, Subie has one of the best reliability records on their CVTs, and I love mine for a daily driver.
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08-30-2017, 12:00 PM | #17 |
Rock Crawler Join Date: Aug 2007 Location: Philadelphia
Posts: 797
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
I can't stand driving my wife's Honda Insight with CVT. It makes me insane. It just sits at 4500 RPM all the time and it has zero punch or passing power. I plan my passes on the highway with a calendar. I'm mostly against owning an electric car and definitely against driving a CVT daily. I just need motor sounds and the ability to shift when I want, how I want.
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08-30-2017, 12:39 PM | #18 |
Rock Crawler Join Date: Mar 2016 Location: Zagreb, Croatia
Posts: 747
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions?
Calendar FWIW I drove a BMW 118d with an 8 speed auto the other day and it sucks donkey balls. It has a sport+ mode in which it sucks donkey balls too, but louder and less fuel efficient. |
08-30-2017, 03:55 PM | #19 | |
Quarry Creeper Join Date: Nov 2005 Location: Western, NC
Posts: 490
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? Quote:
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08-30-2017, 05:48 PM | #20 | |||
Moderator Join Date: Sep 2008 Location: PA
Posts: 13,935
| Re: Why Don't Electric Cars Have Multi-Gear Transmissions? Quote: Quote:
If I want a CVT I'll get a snowmobile. Quote:
Last edited by EeePee; 08-31-2017 at 02:14 AM. Reason: ooopsies | |||
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