Yes, I would electrify my 240SX without hesitation if (1) it handled and accelerated just as well, (2) it cost less than $10k for 100 mile range, (3) it retained the manual transmission, and (4) it was a well-engineered solution.
The custom work required keeps the cost high for such conversions. A relatively affordable new RWD sporty electric car will likely be available before a retrofit seems rational, even considering the emissions benefits.
Why would you want a manual transmission? Why would you want a multi-speed transmission?
Robbie (Forum Supporter) said:In reply to wheelsmithy (Joe-with-an-L) (Forum Supporter) :
you're forgetting the pickemup trucks
Yep, really easy to fit batteries under the bed, cab, in the engine bay, etc. Ladder frome would be good. Crown Vic, anyone.
This tails nicely into the cyberpunk aesthetic. Clearcoat the patina, make the interior liveable, and have a silent, clutchless cruiser.
Keith Tanner said:If only I had a Miata on my lift right now. Wait a second...
Eyeballing, I think you could fit three of them in a Miata tunnel. I'll back that up with a tape measure soon.
As for software, there are third party controllers that can run a Tesla Model S power unit. Not the 3 yet to the best of my knowledge. Pity, because the 3 motors are very clearly 2-3 generations further along in evolution although they're not as monstrously strong.
Two in a tunnel without any modifications. They'll run roughly from the rear bulkhead to the front shock towers. You could fit a third if you were willing to widen the top of the tunnel by a couple of inches.
Or, fun fact, the exhaust on my V8 NA hangs a total of 3" below the floorpan. I think you could plausibly "skateboard" the car without a major problem.
Keith Tanner said:If only I had a Miata on my lift right now. Wait a second...
My Miata's on the floor, but I have an FD on the lift. Poking a tape measure up there it looks like there are spots where there's only about 10 inches of vertical clearance, so one of those packs would have a couple inches sticking down into the breeze.
I would not do it on a plane, I would not do it on a train, I would not do it to my GTI, I would not do it to my CB500, I most certainly would not do it to my Mustang. Before I get beat up on, I have nothing against y'all folks wanting to I just simply have 0 interest in it. Heck, I don't even like infotainment in my gf's car. What happened to a good ole fashioned radio that makes the loud tunes rattle my grey stuff in my braincase?
And yes, I realize none of those are 'compact sports cars' but this is GRM so what even is staying on topic
In reply to Keith Tanner :
Manual transmission mostly because shifting is fun and you can also use a lower power electric motor.
vsquaredbyrho said:Manual transmission mostly because shifting is fun and you can also use a lower power electric motor.
The electric motors that are commonly used for EVs have a flat power curve across a wide range of RPMS and it's power-at-the-wheels that determines acceleration. Any torque multiplication you do by downshifting the transmission is offset by the loss in torque generated at those higher RPMs. Transmissions really don't make any sense unless you need to go outside of the range at which the electric motor can generate useful torque -- this basically means up to a top speed of 125 or so.
Does an EV motor use less battery power at a lower RPM ?
If so a 2 speed with 1st gear set at 35mph and 2nd gear set for best "fuel" usage at 75mph
just a thought,,,,,
In reply to codrus (Forum Supporter) :
Flat horsepower curve is the part that I like.
To put that in a manual transmission perspective, except for minor differences with respect to motor efficiency and gear losses, downshifting would not increase your ability to accelerate and upshifting would not decrease it, because the torque at the wheels ends up being the same no matter what speed the motor is turning at. So all a shiftable transmission would do is increase parasitic losses.
This is also why I like a well calibrated CVT. The engine can stay at the same horsepower, you're never in the wrong gear like if you had only five or six or ten discrete gears.
The motors typically have about a flat torque curve from 0-3k rpm. If you have enough torque you can gear it to be quick up to beyond highway speeds with one gear. If you want to use a lower torque motor or want to accelerate above 100mph quickly you would probably benefit from a two speed with a bigger spread than a typical box.
MrJoshua said:The motors typically have about a flat torque curve from 0-3k rpm. If you have enough torque you can gear it to be quick up to beyond highway speeds with one gear. If you want to use a lower torque motor or want to accelerate above 100mph quickly you would probably benefit from a two speed with a bigger spread than a typical box.
The only reason for this is usually because they have been artificially limited to lower start up torque so they don't break stuff.
Most motors have a torque curve that drops off linearly with RPM, which creates a power curve that is a straight line.
ProDarwin said:MrJoshua said:The motors typically have about a flat torque curve from 0-3k rpm. If you have enough torque you can gear it to be quick up to beyond highway speeds with one gear. If you want to use a lower torque motor or want to accelerate above 100mph quickly you would probably benefit from a two speed with a bigger spread than a typical box.
The only reason for this is usually because they have been artificially limited to lower start up torque so they don't break stuff.
Most motors have a torque curve that drops off linearly with RPM, which creates a power curve that is a straight line.
If you don't current limit. They all current limit for various reasons which gives you about 3k of constant torque, then about 1.5k of constant power, then both torque and power fall off from there. A transmission would indeed help acceleration if you wanted more torque to the wheels at startup. Tesla just supersized everything which means they have enough torque to gear it for great acceleration and pretty good top speed with only one gear. A Tesla motor in anything half the weight of a Tesla=hold on tight!
MrJoshua said:The motors typically have about a flat torque curve from 0-3k rpm. If you have enough torque you can gear it to be quick up to beyond highway speeds with one gear. If you want to use a lower torque motor or want to accelerate above 100mph quickly you would probably benefit from a two speed with a bigger spread than a typical box.
With ICE, your power available is in the engine. The transmission multiplies the torque at some power loss and is a small fraction of that weight. Adding gears makes sense. With electric, your power output is how many amps*volts you can pull from the battery pack (generally sufficient once the pack is big enough for usable range) and the size of the motor. But in this case, the motor is much lighter weight than the battery back. Yes, you can add a transmission, but the extra mass/cost/complexity of adding a two speed is generally more than just making the motor big enough to have the torque you wanted without adding gears. With electric, the motor is the cheapest, simplest, most rugged portion of the system. Just beefing it up is the easy button.
It is also apparently fairly difficult to build a transmission that will stand up to the electric motors, something about the instant torque stresses them. Tesla went through several iterations on their original Roadster before giving up and going with a fixed reduction gear ratio.
My $.02 on this as having worked for a company that converted Promaster vans to all electric.
Though they don't realize it, most people will be perfectly happy with 100 mile range. To work, from work, a few errands, come home and plug it in.
Choose your battery chemistry carefully. Lithium Ion or "battery chem of the day" will get you the most performance/range/light weight BUT is the most dangerous as far as fire. Big item at the battery show a couple years ago was a separator to keep one cell from igniting the next. On the vans we used lithium iron phosphate, you could shoot the cell and all that happens is the filling falls out. I also considered going electric for my Fmod but cost was prohibitive for the batteries. For that the proper battery would have been lithium titanante. Very fast discharge (16X!!!) and charge though limited range (not a big issue for a SOLO car).
You also have some other things that need to be included. For a street car you will need an onboard charger that converts the 220 VAC to DC for charging the batteries. You need a Battery Management System to balance the cells and monitor cell condition. You need a DC/DC converter to run the control systems and charge the 12V battery (it keeps everything alive when the vehicle is "off". One of our most common trouble calls "the van won't charge or turn on"... check the 12V and let me know!). If you have a later street vehicle you will need a computer to communicate with the CANBUS to talk to the instrument cluster and the ECU, body control computer, etc. This will get more complicated over time as automakers clamp down on vehicle software.
As far as motors and gearboxes, an AC motor has many advantages, not the least of which is regenerative braking. Choosing a gearbox depends on your motor. We used a single speed gearbox that with the UQM motor was only good for 56 MPH, with the TM4 it could hit 85 or so. (Remember, this was 7600 pounds of shuttle bus! Would you really want to go more than 55 with a hotel bus driver?) Look at the rated RPM and torque of the motor and wheel size, etc, and do the math.
Good news, you can locate the batteries low in the chassis and tune your weight balance. That 7600 pound van... handled pretty good really.
californiamilleghia said:Does an EV motor use less battery power at a lower RPM ?
If so a 2 speed with 1st gear set at 35mph and 2nd gear set for best "fuel" usage at 75mph
just a thought,,,,,
Using less power at lower RPM would imply that they are more efficient at lower RPM. Watts is a measure of power AND electricity.
Meanwhile, the whole thing where people say "max torque is at zero RPM" means that electric motors, by definition, are the most inefficient there. Zero RPM means zero power, no work is being done, but if there is torque then electricity is being used. That's infinite inefficiency. I'm sure it does get better from there.
Any theoretical gains you might get from spinning the motor slower would be more than lost by the 20% or so transmission losses in a gearset.
californiamilleghia said:Does an EV motor use less battery power at a lower RPM ?
If so a 2 speed with 1st gear set at 35mph and 2nd gear set for best "fuel" usage at 75mph
just a thought,,,,,
Other way around. Peak efficiency is at higher RPM. That is why so many EV's have top speeds just above (or not above) highway speeds.
Pete. (l33t FS) said:Watts is a measure of power AND electricity.
Legit question about this. Since Watts is a measure we assign to a specific amount of power, and can be stated as "P" (watts) = "E" (volts) multiplied by "I" (Amps [i.e. current]) I beleive it would me more acurate to say that Watts is a measurement of Power. And Power is attained with Voltage AND Current.
Unless you were trying to make a different point that I missed?
LRA ((Locked Rotor Amps) is on some data plates listing how many amps a motor will draw (if the supply can handle it) at full power input - Volts X Current. and is a significant amount larger than running amps. But I'm not sure LRA is what people are referring to.
All electric motors are extremely inefficient at turning electricity into movement. Some of those inefficiencies are responsible for the waste heat. it tales power to produce that waste heat.But so are all methods! It would take a smarter man than I to figure out what method is the least inefficient. Once a viable superconductor, or perpetual motion is available, we will be able to change that.
03Panther said:Pete. (l33t FS) said:Watts is a measure of power AND electricity.
Legit question about this. Since Watts is a measure we assign to a specific amount of power, and can be stated as "P" (watts) = "E" (volts) multiplied by "I" (Amps [i.e. current]) I beleive it would me more acurate to say that Watts is a measurement of Power. And Power is attained with Voltage AND Current.
Unless you were trying to make a different point that I missed?
LRA ((Locked Rotor Amps) is on some data plates listing how many amps a motor will draw (if the supply can handle it) at full power input - Volts X Current. and is a significant amount larger than running amps. But I'm not sure LRA is what people are referring to.
All electric motors are extremely inefficient at turning electricity into movement. Some of those inefficiencies are responsible for the waste heat. it tales power to produce that waste heat.But so are all methods! It would take a smarter man than I to figure out what method is the least inefficient. Once a viable superconductor, or perpetual motion is available, we will be able to change that.
Watts can measure power in terms of electricity and also power as an alternate unit for HP.
I believe (shooting from the hip here) most electric motors convert 80-90% of the electrical energy into rotational energy. This has been true for a long time. Gasoline engines are more like 30-35% (and then, only at WOT - they are worse at part throttle and idle conditions). Diesel is slightly better, but maybe up to 40%.
Here's a question for you: does an electric motor need a radiator?
I also drive an AW11 and have given the idea of converting to EV a little thought over the years. Given that the MR2 was originally conceived as a sporty but decidedly humble parts-bin commuter, it's not exactly blasphemy. Since I use my car primarily for workday commutes, which are under ten miles, range wouldn't be a problem. Blistering performance really isn't necessary, either, since most people don't commute at WOT. The car might be a little heavier than stock, wouldn't likely accelerate much slower, and could still be a relatively engaging drive.
My particular car is a little warmed over, and I probably wouldn't be eager to convert it to electric, but it would be an interesting alternative to a bone stock example.
Robbie (Forum Supporter) said:03Panther said:Pete. (l33t FS) said:Watts is a measure of power AND electricity.
Legit question about this. Since Watts is a measure we assign to a specific amount of power, and can be stated as "P" (watts) = "E" (volts) multiplied by "I" (Amps [i.e. current]) I beleive it would me more acurate to say that Watts is a measurement of Power. And Power is attained with Voltage AND Current.
Unless you were trying to make a different point that I missed?
LRA ((Locked Rotor Amps) is on some data plates listing how many amps a motor will draw (if the supply can handle it) at full power input - Volts X Current. and is a significant amount larger than running amps. But I'm not sure LRA is what people are referring to.
All electric motors are extremely inefficient at turning electricity into movement. Some of those inefficiencies are responsible for the waste heat. it tales power to produce that waste heat.But so are all methods! It would take a smarter man than I to figure out what method is the least inefficient. Once a viable superconductor, or perpetual motion is available, we will be able to change that.
Watts can measure power in terms of electricity and also power as an alternate unit for HP.
I believe (shooting from the hip here) most electric motors convert 80-90% of the electrical energy into rotational energy. This has been true for a long time. Gasoline engines are more like 30-35% (and then, only at WOT - they are worse at part throttle and idle conditions). Diesel is slightly better, but maybe up to 40%.
Here's a question for you: does an electric motor need a radiator?
I think Mercedes got their F1 power train above 50% efficiency. That was a pretty big deal.
Electric motors and do generate heat. The Model 3 uses it for interior heat iirc and to help heat cold batteries. But it does something odd to the motor to generate more, I don't know the details.
Toyota recently said their next gen engine will be 40% efficient otto cycle and 41% atkinson.
IIRC some container ships exceed 50% eff (2 stroke diesel)
In reply to Robbie (Forum Supporter) :
In reverse,
Yes. In a way. Any electric motor, that has a load, will need some form of cooling. Either from a heat sink, a fan or both. I think I have heard of some that are liquid cooled, and that would imply a radiator. 
I can't say tha for sure, though.
I was in class for such things some 40 yr ago, before I started a mechanical degree. Sadly, never finished either! I seem to remember the numbers (for electric) being much lower than that. no clue about the spread, but that also doesn't factor in how inefficient generating and moving electricity is. After that, my head starts to hurt.
and yep. I don't know what the conversion factor is, but its not hard to look up. Ugly's prob. has it, as well as the McMasters catalog. I think some can plug in some standard effencity percentages. But not a part of my daily grind.
It's quite clear that the amount of waste heat from an EV drivetrain is dramatically lower than that of an ICE. The heater in an ICE is driven by waste heat from the engine and it's a lot of BTUs. The EV needs heaters for the batteries, never mind the cabin.
I'm pretty sure we've already had this discussion about transmission losses of electricity (considerably lower than your recollections) and about how oil does not magically appear in fuel tanks.
Electrical transmission is roughly 95% efficient.
The U.S. Energy Information Administration (EIA) estimates that electricity transmission and distribution (T&D) losses equaled about 5% of the electricity transmitted and distributed in the United States in 2015 through 2019.
Efficiency chart for a permanent magnet EV motor such as that in the Model 3.
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