I wanna go 35mph for 25 miles. can't get answers

N

nextphase

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Sep 23, 2011
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Hello all and thanks for any suggestions you may give. Very new to EV's and electric motors/batteries, etc in general. Can't seem to get answers I need from other site(s). I have an X-treme scooter body with the motor, batteries and controller removed. Can anyone please suggest what motor, battery configuration and controller I might use to get this thing going a respectable 35-36 mph for a respectable 20-25 mile range? 20mph is a joke when talking real commuting(using roads with cars!). Furthermore, I believe Hoverboards are a real ripoff. Even their new PPV only goes 30mph(website) and it's listed at $3,995!
AND IT"S NOT EVEN AVAILABLE!

I think I need an outrunner such as an 80100 KV130 with at least 50 volts of battery output to get me even close.(I've read I should try for LiPoly's)

I must admit the extent of my knowledge in this field isn't much greater than Volts = speed; mAh's = "size of the tank"; and C = flow(i.e. how fast the juice comes out). I know even less about controllers and Hall sensors. I am not dumb but I do need it explained to me like i'm a 10-year-old, at least in the beginning.

Thanks to all and I hope I can return the favor. I will be sending contributions to help fund this site.

Sincerely,

nextphase
 
Which scooter do you have?

You'll need about 1200W into the motor to go ~30mph, 1500W to go 35mph. To get 25 miles range, that's 0.71 hours, round it up to 0.8 hours for traffic. At 1500W this is 1200watt-hours of capacity. If you only want to use 80% of your battery pack to preserve life, you need a 1500 watt-hour pack.

What gear reduction does your scooter have? What RPM do you expect the motor to turn at 35mph? This will tell you what voltage you need.

LiPo is definitely the way to go for this much capacity & power.
 
Hello DennyT! Thanks so much for your reply! I don't really know about rpm's but someone posted that I'd need the smallest sprocket I could fit on the front(motor) and the largest I could fit on the rear wheel. I'm guessing I'd need roughly 11 tooth on the front with 44+ tooth on the rear, but again, I'm guessing.

Could you possibly tell me if I even need a 6000+ watt outrunner or could I achieve these speeds with, say, a 2000 or 3000 watt outrunner just configured differently? Is it because only the larger outrunners are rated for 50+ volt capacities? I am pondering buying an outrunner rated at 4000watt; 50 volt capacity.

(If you don't feel like answering all of these questions, I completely understand.)

I will look for the answers to your questions now as well.

Thank you again, DannyT.

Sincerely,
nextphase
 
PS, DannyT: Just saw the pics on the link. Very nice build! I, too, am a life-long bicyclist. BMX (both racing and freestyle) as well as a messenger in Boston. And, no, I've never worn anything spandex in my life. There's the $200 outfit weekend warrior, then there are guys like us. Grittier and more hardcore. I wore long John's over cargo shorts. Had a Bianchi fixie with a solo front brake and "steerhorn" bars. Peace.

-nextphase
 
Aah, so you just have a rear wheel and no other drivetrain parts or gearboxes to work with?

Here's what you need to do to calcualate motor RPM at speed.

1. Measure wheel circumference either by rollout on the floor, or outside diamter x 3.14. For this example, let's say it's 20" OD, 62.8" circumference (inches per revolution).

2. Pick a ground speed, say 35mph. 35 mph= 616 inches per second (google search on "35 miles per hour in inches per second". It's a great units converter)

3. Calculate your wheel RPM. 616 inches per second / 62.8 inches per revolution = 9.8 revolutions per second. X 60 seconds / minute = 589 RPM at the wheel.

4. Pick sprocket teeth (guess and check). Don't go less than 12t or maybe 11, but it will wear fast. Let's start with 12t front and 48t rear. Motor RPM = Wheel RPM X rear teeth / front teeth. So for our example, Motor RPM = 589 x 48 / 12 = 2356RPM.

Now, I don't have any experience with RC motors, but that seems really low. You'll probably need a dual-stage reduction to get it up in the 10K RPM range, or wherever they're happy.

If you want to find out the voltage you need to run it at this speed, divide motor RPM by motor KV (RPMs / Volt). 2356RPM / 130KV = 18.1V. So, if the motor is rated for 50V then you're spinning it way too slow to be efficient, and probably stalling / creating heat.

Cheers and good luck!
 
FWIW, a number of vehicles list a specific maximum speed to comply with regulations or laws governing them, so that they remain legally that class of vehicle for manufacturing and registration purposes. Sometimes they actually have a limiter in them to prevent going over that, or they actually do not have the power necessary to do so.

But sometimes they *can* actually easily exceed the specified speed, by some reasonable percentage, even in stock condition.


Just a heads up on why you might have trouble finding faster ones than 30MPH, since scooters tend to fit in Moped classification, which is often limited to 30.


All that said, sometimes you can easily simply overvolt an existing unit that only goes 30, but has no actual limiter, as long as you have room for the extra batteries. It is not a linear relationship, though, because it will take notably more power for that extra 5MPH+ than the 1/6 of original voltage you might expect. ;)
 
which x-treme scooter ?

like this?
(btw, i just picked up a used one )

x600-exploded-red_1_.jpg


seems like death to go 35mph on 10" wheels.. :|
 
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