91–100 of 219 posts
Aside from not providing much of any performance benefit, this will introduce difficulty coordinating regenerative braking through the shift point. One of my former employers had a group trying really hard to make a 2-speed for EVs make sense. It just doesn't. If there is an efficiency gain, it's probably better to throw the extra money and weight into the motor. An exception might be if you want to cruise at 120+ mp…
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Porche appears to be claiming that one of the features of the Taycan is repeated launch control 0-60s without overheating or other problems that Telsa is warning people about when you use ludicrous mode: https://www.youtube.com/watch?v=TP9kokeyxGU
That was a issue with the Model S, not with the P3D. I suspect that when they switch over the S to the new style batteries, it goes away.
So Tesla gets to pick whether they want a Model S that doesn't overheat, or a Model S that's slower to 60 than a Taycan.
Aside from not providing much of any performance benefit, this will introduce difficulty coordinating regenerative braking through the shift point. One of my former employers had a group trying really hard to make a 2-speed for EVs make sense. It just doesn't. If there is an efficiency gain, it's probably better to throw the extra money and weight into the motor. An exception might be if you want to cruise at 120+ mp…
Which part of cruising at 120+ mph for long distances is not realistic?
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Since when is the priority to not offend the drivers around you? We must live in completely different worlds. My comment re: antisocial was more in reference to noise pollution and disturbing residents at home where they have a reasonable expectation of peace and quiet.
> Since when is the priority to not offend the drivers around you? Caring about others is pretty much rule #1 about living in a polite society. People who don't care about others are called sociopaths, literally anti-social behavior. Prioritizing safety on the streets, making sure you send clear signals with your actions, etc. etc. Its all part of driving and being a good citizen on the road. Part of that is absolute…
I agree with your other comments about driving in traffic. avoiding large speed differentials when you are surrounded by other cars is very much your responsibility.
In dual-motor (front, rear) Tesla vehicles, each motor is on a different gear ratio for optimal power bands.
I wonder if this is part of why their dual-motor models get better range. I could see it being better for regenerative braking, too.
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> The only reason to push 0-60 times is for drag-racing really. Wat? Most people care about accelerating from a standstill to the average legal speed limits. 0-60 captures that perfectly. It's incredibly relevant to the general public's driving patterns.
People rarely do a full power 0-60 with a car that can do it under 5 seconds. More likely they go from 30-60 or similar.
In more rural locations you'll commonly have a 90 degree turn onto a 60-70mph road.
I probably wouldn't if it were 3s 0-60 though.
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A 5% efficiency gain might be a big deal when it comes to motor heat. Electric motors tend to be around 85-90% efficient or so, and if you can get the motor from, say, 85% efficient to 90% efficient, that might translate to a one-third reduction in waste heat.
> that might translate to a one-third reduction in waste heat. Is that a big deal, though, compared to battery heat? Or is it in the context of a race scenario?
The battery is big, so it has high thermal mass and lots of area for cooling. The motor is small. Motors can also easily be thermally limited. A permanent magnet motor that overheats will demagnetize and be destroyed. Induction motors and other non-permanent-magnet motors are less sensitive, but resistance goes up and metals and glues soften at higher temperature.
However, battery prices are falling rapidly. They dropped 35% in 2018 alone. That being the case, I am guessing most ev manufacturers will stick with single-speed powertrains, and focus their technological efforts elsewhere.
Aside from not providing much of any performance benefit, this will introduce difficulty coordinating regenerative braking through the shift point. One of my former employers had a group trying really hard to make a 2-speed for EVs make sense. It just doesn't. If there is an efficiency gain, it's probably better to throw the extra money and weight into the motor. An exception might be if you want to cruise at 120+ mp…
Which part of cruising at 120+ mph for long distances is not realistic?
Earlier quoted context omitted.
Porsche are experts in transmissions and gearboxes, but are starting (almost) from scratch for batteries. Give them a few years, they'll catch on.
I suspect it might be motors too. Why do they even need gears? I can see why we need differentials (until we have one motor per wheel), but can't gears be done in some electronic way with clever arrangements of motor For example, the tesla has ~10:1 reduction ratio gearing, but I wonder if there's a clever way of rearranging the poles/coils of the motor, maybe like a crankshaft, so you get the best torque matched to…
electric motors don't actually have flat torque curves. they make peak torque at zero rpm and then gradually decrease. the curve is much smoother than an ICE, but it's still possible to increase the performance of the engine by keeping it in an optimal rpm range provided you don't add too much weight and/or power loss through the transmission.