John Phoenix

If we can go 20 miles round trip at 30 miles an hour with a 750 watt hub motor and a 48 volt 20 ah battery - why then cannot we design a small efficient fast car?

I just gave this world a billion dollar idea. Stupid of me to throw away all that money, I know, but I believe it can be done. I look at what Tesla motors is doing and the prices they charge. We could make a 2 or 4 wheel drive car using more or larger batteries and larger hub motors. We can already make an e-bike do 50 miles per hour with a 1000 watt motor ( and I think it needs something like 72 volts) saw the video of one thats floating around here someplace. If the car was light enough, I say it can be done much cheaper than Tesla. They need to move a ton of weight. This car could be a single or 2 seater and at least half the size of today's cars. This car can be sold dirt cheap.. perhaps 10 to 15 thousand dollars.

Edit: They have cars that now run on Compressed Air. https://www.theatlanticcities.com/com...ssed-air/2967/ These have very light bodies made out of some composit material. This electric car can do the same.. still check out the link because these compressed air cars are awesome - and cheap.

What do you think?

Metal Man

You have done all the engineering on this so that it passes all of the crash tests?

cerewa

If you build it with three wheels, even if it has a car-like body that protects passengers from rain, it can be classified as a motorcycle in the USA (probably many other places). That would mean it doesn't have to conform to automobile safety rules, which would tend to make it just as heavy/expensive as a 'smart' car.

Put two wheels in front and one wheel in back so it balances better when braking.

John Phoenix

No need to. Remember the Yugo or the Hundai? They were not designed to take a hit. Those are mostly selling points of the car manufacturers. There are some guidelines as seen here: https://www.nhtsa.gov/cars/rules/import/fmvss/ depending on what type of vehicle you're making. As with the Compressed Air car above these things probably wont be as study as a car made with steel and heavy iron frames but they will probably give a reasonable amount of crash safety at low speeds. We could look at the data the Compressed Air car company has gathered. Consider motorcycles. Legal in every country but they can't take any hits at all. The operator is exposed. Convertibles are also allowed which provide minimum protection.

This first car would be a prototype. A proof of concept. Once the prototype is made, the car could be reinforced as necessary to meet any requirements. We could limit having to do certain requirements by sticking to a more open model like the convertible.

John Phoenix

Great idea. Thanks for the input.

Metal Man

Yes, three wheels is considered a motorcycle and only needs basic equipment (lights, horn). Four wheels needs all of the safety equipment and testing and approval from the government.

Save yourself the trouble, here it is.
https://www.ebay.com/itm/E-Runner-Y-C...-/300714629165

Scaliboy62

That 3 wheel E-Runner is listed @ 2400 lbs, a good choice for a doner car for the project is the Mazda Miata, would be same weight even lighter with that sweet roadster body style

Doohickie

Incorrect. They both had to pass crash tests before sale in the U.S.

John Phoenix

Cute but this is way too much IMO - overkill. Here are the stats. This thing has almost a 1000 lbs of batteries and weighs over 2500 lbs. Plus, it cost 13.000 dollars. The vehicle I'm thinking of will cost half as much, weight perhaps 1/3 rd of this thing and only have perhaps 150 lbs lbs of batteries if that. It's not made using e-bike technology. I'm talking same type of hub motors, batteries and voltage regulators, only larger than we use for our bikes.

HIGH-SPEED THREE WHEEL VEHICLE Top speed 70 mph with 144 volt system. You can order various options such as power steering, power brakes, etc.
MOTOR POWER: 8.5KW
the motor is water cool. Prismatic battery, needing no cooling system
MOTOR TYPE: AC
NET WEIGHT: 2,420 LBS
BATTERIES WEIGHT: 770 LBS
VOLTAGE: 144v
DRIVEN TYPE: FRONT WHEEL DRIVE
SUSPENSION: FRONT WHEELS
MAX PAYLOAD: 500 lbs
CLIMB GRADE: 30%
STEERING WHEEL CORNER: 2 °
MAX SPEED: 70 MPH
RUNNING RANGE: 110 MILES
BRAKE MODE: DISK BRAKING

Metal Man

Let us know how you make out.

John Phoenix

It will be a while before I can personally try to build something like this. The purpose of this thread is for us to discuss these possibilities and ideas on how best to make it work. It's for community input, not a one man project. Perhaps some of us can get together in the future and collaborate on the building of this car prototype once we have the base designs laid out.

turbo1889

So in other words this is a designers sandbox thread?

Okay, I'll bite.

I'm thinking tadpole trike (two steering wheels in front one wheel in back) with the two front wheels being 26"x2.0 heavy duty pucture resistant reinforced sidewall bicycle tires on heavy duty double wall rims with 48 spokes that are 12ga. stainless with big 2-KW each front hub motors that are wound for high RPM running on 72V. And then use lighter weight motorcycle rear tire (heavier duty then a regular bicycle tire but not like a big heavy motorcycle tire) on the rear with a toothed belt or chain drive running off of a 4-KW 144V mid-mount motor with a simple three speed constant mesh planitary gear transmission on the mid mount motor head. Two 72V LiFePO4 battery packs each rated for 60+Ah wired in parallel for the front hub-motors and in series for the rear mid-mount motor. The three brushless motor controllers and a rear transmission shifter servo are slaved to a master control computer which has a throttle and brake position sensor.

The vehicle is primarily rear wheel drive with the master control computer taking throttle input and shifting the three speed transmission on the rear drive assembly so that it acts like an automatic transmission even though it is just a simple manual band shifting assembly it is just the master control computer does the shifting. The front dirct drive hub motors kick in at the top end of the throttle range to give the extra boost and they are wound for best efficiency at that speed. There is also a "fowl weather mode" switch on the master control computer that runs the front hub motors all the time even though they aren't very efficient at lower speed for 3x3 drive traction on slick roads. Front hub motors are also used for regenerative braking with (real) hydrolic disk brakes on all three wheels that engage once the brake lever is engaged beyond the initual regenerative braking.

At full power at the top of the throttle range that vehicle would have 8-KW of power and would be able to maintain that power output level for a full hour and should be able to push beyond 60-mph with an aerodynamic bubble cockpit set-up. Using just the 4-KW rear motor which has the three speed transmission to handle hills and maintain efficiency at lower speeds you should be able to do at least 45-mph before the front hub motors kick in and maintain that speed for at least two hours on the battery charge.

Would certainly work for my commuting needs ~ just don't have the loose dough and time to build it not to mention the hastle of getting it titled and licensed as a homebuilt motorcycle.

rscamp

Ha! I was going to say the same thing...

FMB42

I suggest that you consider the following:

1. I'm not sure what top speed you're expecting in your design, but 50 mph isn't fast in car terms. This is not to mention that a top speed of 50mph would often be "insufficient" on roadways with posted maximum speeds of 40-45 mph.

2. The "top speed" examples (of other E vehicles) that you provide were most likely achieved on flat ground, on a near perfect road surface, and under little or no wind conditions.

3. DOT requirements must be applied to your design (this includes DOT approved tires, rims, and lighting, etc, etc).

4. The above factors, and the increased drag of a 3 or 4 wheeled vehicle, will severely degrade your performance estimates.

5. Your cost estimate is very much underestimated imo (various commercially available electric motorcycles that fall within your performance parameters start out at between 10-15k dollars).

6. Other factors include braking and acceleration performance, stability, and reliability.

All of these factors can, and often do, result in serious cost over-runs and manufacturing snags.

John Phoenix

There is this for about 6000 dollars. The BugE. Comes in kit form. Street legal in the USA. DOT requirements aren't so tough. My electric bike is already DOT approved. LOL https://www.bugev.net/ Or get one from Harvey Coachworks https://www.youtube.com/watch?v=8LNn...eature=related $8.500 if you let HarveEV build one for you. https://www.harveyev.com/products/buge.html

The would not have to go above 50. Thats plenty fast enough within the city. You ONLY need over 50 mph if your going on the highway. Crash tests, not a problem if this is made as a 3 wheel car.

Another cool car: the Trivia https://www.youtube.com/watch?v=gpBl...eature=related

turbo1998, I see you have given this a lot of thought. Neat ideas there dude. Tell me, why do you like the two wheels in the front as opposed to them being in the back with a single wheel in front?

turbo1889

Three main reasons why a tadpole trike is far superior to a conventional trike:
1. ~ A tadpole trike is naturally stable at speed and in the turns, a conventional trike is naturally un-stable at speed and in the turns. This is the reason they stopped making 3-wheeler ATV's (off road vehicle with the big fat tires in the one steering wheel up front and two drive wheels in back arrangement) and now they only commonly sell 4-wheeler ATV's for liability reasons.
2. ~ Well over 2/3 of the braking capability of almost any light vehicle is in the front wheel(s) so with that being an almost unavoidable fact of physics would you prefer two braking wheels up front and one in the rear or one braking wheel up front and two in the rear? You will get much better braking capability with a tadpole vs. conventional trike set-up if all wheels are equipped with brakes.
3. ~ Aerodynamically at sub-sonic velocities the streamlining of the rear of the vehicle is more important to reducing air drag then the front of the vehicle. Take a quick look at the fuselage design of a 737 airplane or the shape of a modern submarine. The tail is far more streamlined then the nose with the tail being a slow long taper and the nose being a short blunt curve compared to the tail. Only on aircraft intended for super-sonic flight will you find a long heavily streamlined pointy nose. The same exact rules apply to ground vehicles, putting the double wheels up front in general makes for a more aerodynamic body shape then doing the reverse since it is more important for drag reduction for the tail of the vehicle to be streamlined down with a long smooth taper.


As to my general idea I was thinking 250 pounds of batteries + 150 pounds frame, body, and drive-train weight + 250 pounds of driver weight that at full throttle can go just a little over 60 mph on the flat to keep up with other traffic but generally is designed to "cruise" at 45-mph or less and can maintain at least that speed up most hills so as not to tick off other drivers. That was the general guidelines that I was trying to stay within and end up with an all-weather short range single occupant light-weight commuter vehicle.

rscamp

All good points and this is why velomobiles, which are extremely efficient, use the tadpole configuration. But regarding point 1, a tadpole configuration approaches the cornering stability of a four wheel vehicle when braking hard. But under hard acceleration, they most definitely do not. The good thing is the former is rather more necessary and important.

FMB42

Really? Next time you drive within your "city" take a look at the max speed limits. You'll probably notice a fair number of roads that have max posted limits of 40 and 45 mph. Next, take notice of the number of drivers that actually drive within the posted speed limits (both in the slow and fast lanes). Forty - 45mph speed limits, like I said before, would put your "topped out" 50mph electric at "risk" due to the fact that many people routinely drive at 5-10+ mph over the posted limit. However, an electric vehicle top speed of 40-45mph would be relatively OK (imo) on roads limited to 30-35mph. Running at such speeds will, of course, greatly limit your range (again, manufacturers often publish range claims under ideal conditions). Also keep in mind that your electric vehicle will need to have a reasonable acceleration, that is, unless you want other drivers to be tailgating you as you pull away from every light and stop sign.

Ok, so you're obviously very new at this. Oh well, the good thing is that you're asking lots of questions.

John Phoenix

The BugE has a top speed of 45 miles per hour and is approved for street legal use. I'm not interested in not being an annoyance for those breaking the law. If they have to go faster and break the law, they can suck eggs being stuck behind me. Such a vehicle just would not have much passing power to pass those doing 45 but that's not a big problem. I agree that a reasonable amount of acceleration is necessary.

New to what.. designing a car? Differences in 3 wheel vehicles? I suppose you are an expert? As for my question, notice that the Triva has one wheel in front and two in the back. Obviously that company didn't think it was a big factor, thats why I asked Turbo his opinion. I've been a member here and had my e-bike as long as you've been a member here - and I have more posts. I suppose you can't be right so your being condescending. How dare you. You don't know me or what I know and don't know.

Turbo 1998, Thanks for the info.

FMB42

Oh dear, "how dare" I mention various potential issues with you and your "idea" (after your equally condescending "lol" response...). I see nothing funny about operating a possibly under powered and/or poor performing vehicle on public roads (regardless of the posted max speeds). Again, manufacturers often make vehicle performance claims that do not reflect reality. This is especially true of e bike manufacturers. These manufacturers almost always measure their vehicle performance during zero wind conditions on dead level roads that offer near perfect surfaces. They also often use sub 100 pound operators while doing so. This is why very few "real world" e bike operators manage to realize the range and speed performance that manufacturers claim. Add rough roads and just a slight grade and/or headwind into the mix and you'll sometimes end up with a dangerously under powered "45mph" vehicle that will be lucky to do 35 in real world conditions. These "every day" factors, while adding an average operator weight of 155-185 pounds, can also degrade any claimed braking and acceleration performance. Btw, membership duration and the number of posts made here is no guaranty that you, or I, have any appreciable real life bicycle/e bike/motorcycle experience. However, my overall motorcycle and auto experience (both casual and professional) can be measured in decades (I've been riding bicycles for ~ 50 years). Does this make me an "expert"? No it doesn't. But it does give me reason to point out various issues with your idea. Meanwhile, I'd much rather sound "condescending" to you than to see you waste time and money building and/or buying such a vehicle. Nor to I care to see you get hurt while operating such a vehicle. Quote: "they can suck eggs being stuck behind me" Let us know how this attitude works out for you...

CigTech

I know of one ped/bike/car thing that I have built. It weight of the frame is about 30 lbs. It started out as a ped/car with 2 seats. but quickly mod to a e-ped/bike/car. The hole thing weight about 176 lbs. I put a hub motor (500 watts Cheap motor) on the left rear wheel, and the right rear wheel was ped powered. It has 4 wheels. any ways it worked grate for a small county town. It would do 24 mph and had a slow take off But got you up and down the big hills of that small town. Has a 48v 500w motor and four SLA car battery. It has a 15 mile range with lots of big hills.

Now to the better qustion. Would I drive this around a big town? NO, not just no but HELL NO. I would get run over in I'd says 3 miles if that.
And by the way I never got pulled over by the small town cops, but they might not like this bike on big city roads.

Here is a photo of it after the bike was done,



BTW - I put my truck in a ducth one sonwy day so I use it for a trade in on a new (used) car. At that time a had a 32 mile drive to work and the bike would not get there. I got 1500.00 for the trade in. it cost about 750.00 to make.

turbo1889

As for speed under less then ideal conditions. It is a well known general rule of thumb for most vehicles that the energy input required to increase velocity is to the square of the increase. Or in other words if you want to double the speed you have to put in four times the energy (2^2=4) and if you want to triple the speed you have to put in nine times the energy (3^2=9) and if you want to quadruple the speed you need to put in sixteen times the energy (4^2=16). It is not a linear relationship such that if you double the power of the motor you get double the speed; rather if you double the power of the motor you only increase the speed by approx 41.4% (2=1.414^2).

It was on that basis that for my suggested design I came up with the idea for vehicle that would never exceed 750 pounds weight even with a grossly overweight rider and provided the rider did not exceed 250 pounds (which is about as heavy as even the tallest broadest shouldered biggest boned human can get without being obese) would tip the scales at no more then 650 pounds and that 8-kw worth of electric motor should be able to push such a vehicle to 60-mph on the flat at max throttle provided the body was an aerodynamic pod shape and that at or below 45-mph only the power of the 4-kw rear drive motor with the three speed transmission would be needed. Multiple 45-mph by 1.414 and you get 63+ mph so if only 4-kw is truly needed for speeds of 45-mph when the front hub motors kick in and double the power input that should be enough to bring the speed up to that level. As to how I have a good idea that 4-kw in a mid-drive arrangement with multiple gears in-between it and the rear wheel should be sufficient to drive a vehicle of 650 pounds weight and air drag profile to that speed. With an aerodynamic pod body the drag should actually be less then a far from aerodynamic regular bike with the rider in an upright riding position and since I have used a mere 250-watt geared down mid-drive motor to push myself on such a bike up a slight hill while pulling two other people behind me on their bikes with a tow rope at a speed a little more then 10-mph it follows that with 4-kw that being sixteen times the power input I should be able to push a vehicle of equivalent total weight and better aerodynamics to four times the velocity. And I also know that a 500-watt motor set-up in crank-drive stoker-monkey arrangement is capable of pushing a heavily laden cargo bike on the flat at nearly 20-mph so it follows through that 4-kw which is eight times the energy should be sufficient to push a vehicle of equal weight and aerodynamics to nearly three times the velocity (its 8 times the power not nine times so it would be a little less then triple velocity). Granted that cargo bike didn't weigh in at 650 pounds including the rider, more like 450 or so but it also had very poor aerodynamics and I'm only trying to reach 45-mph with 4-kw of power which is closer to double then triple the velocity. As to the advantage of a streamlined pod consider that the sustained distance solo human only powdered vehicle record is over 40 miles in one hour for such a streamlined pod shaped vehicle under human power alone which even for a world class athlete is not going to be more then 350 watts output for an extended period of time. 500+ watts output is possible for a human in a short sprint but not for sustained distance and time. Long story short, 4-kw should do the trick for an aerodynamic pod shaped vehicle of 650 pounds to push it to 45-mph speeds under realistic operating conditions. And if that is true by the square of energy input doubling the power to 8-kw should allow the vehicle to reach 60-mph under realistic operating conditions.

A single seat tad-pole trike that has a total vehicle weight less then 3/8-ton, has a sporty fighter jet like cockpit, and is able to reach speeds of 60-mph under realistic conditions at the top of its performance range and has a range of at least 60-miles even when constantly operated at full throttle is something that is a serious potential vehicle for many commuters that just need something to get them and maybe a briefcase and laptop back and forth to work under all weather conditions without messing up their suit or having to change or shower once they reach work.

turbo1889

---- I don't know how much Cig-Tech weighs
---- I don't know if that 24 mph quote of his was with just himself or with a passenger in the second seat
---- I don't know if that 24 mph quote of his includes him pedaling as well as running the motor or not.
---- I don't know under what conditions this 24 mph top speed was obtained

ASSumptions:

---- Cig-Tech weighs 149 pounds
---- No passenger no additional cargo weight
---- He was pedaling like a mad man putting out super athlete 500 watts of power for a short sprint to reach 24 mph
---- Flat ground no wind for his 24-mph

Fact to point out obvious from his picture:

---- His e-ped-car is not a streamlined aerodynamic design

The Math:

---- Total Power input = 1-kw (500watt electric hub motor + Cig-Tech pedaling like a mad man putting out 500watts himself)
---- Total Weight = 325 pounds
---- Resulting Velocity = 24 mph

It is true that weight is a liner relationship to motor power thus if it takes 1-kw to push a vehicle with a total weight of 325 pound to 24-mph on flat ground it will take twice the motor power to push it to the same velocity if we add an additional 325 pounds of cargo weight to the vehicle. Thus we are now sitting at 2-kw to push his vehicle to the same 24-mph if we double the weight to 650 pounds. Then if we increase the power to 8-kw which is four times the power that should double the speed to 48-mph.

Question ~ Do you think we could get an extra 12-mph out of it to push it up to 60-mph if we reduced the road drag down to three wheels instead of four and used an aerodynamic pod shaped body like a jet fighter cockpit instead? I think so.

CigTech

But as you probley can tell the frame is PVC pipe. So do you want to push it to 60 mph with only PVC around you? I don't.

hairytoes

Kinetic energy calculation of a moving object does not equal the power required to attain a speed.

Sorry to pour water all over your fire, but your calculations and assumptions are bunk.

See here for some info https://www.physicsforums.com/showthread.php?t=222959