How much fun is 1kW?

[nedfunnell]

Hello all,
I have a 36v 1kW PMDC electric motor and I am considering electrifying my bike with it. How much fun can I have with 1kw? What kind of gearing do you think I ought to aim for? I think my experience will probably be different with PMDC than with hub, correct? Can anyone chime in?
Thanks!

[torqueon]

Judging from your post I am assuming, a non hub drive on a bicycle, with a typical brushed motor from somewhere ?? If this is a true 1 kilowatt rating, you will be quite happy. Your not going to see jessus any time soon, but it will be fun if geared right.

All I know is that my meager lawnmower motor rig, gets me out out the intersections, safely.

I say at 1 kilowatt, gear for 25 MPH if you have hills

You know that once you do this, you will want more power!!

[Trackman417]

How much fun is 1kw?!
Not much fun
2KW is where a tingly feeling starts. Motor feels like it has more guts to throw at you. 3KW is the highest I have been and very fun!

[Samd]

I call b@llshit.
1kW is rather decent if put back thru the gear ratios. And PMDC motors are usually worth two to three times the rating.

1Kw (actually 1100W) gets me to 54kph on the flat: viewtopic.php?f=28&t=18505&start=480

[Trackman417]

Whoops I'm talking about hub motors performance at 1KW

[amberwolf]

On Crazybike2, I had (on the last version of chaindrive) a 650-ish watt PMDC powerchair motor, 4-pole brushed, with a reduction gearbox built in that brought it down near crank speeds at it's origianl 24V, and around double crank speeds at 36V, which also pushed it up around 1KW, IIRC. It was fed via another reduction chaindrive into the regular chaindrive along with the cranks, and it had quite a bit of torque--enough to tear things apart instantly when the chain got misaligned/derailed.

1KW on a DD hubmotor doesn't really feel like much (unless you're going uphill, in which case compared to just pedalling, it's a heckuva boost), but via chaindrive it can do a lot, if you can shift gears to use it for torque at startup and speed later.


I'm becoming spoiled with 4KW+ for momentary use at startup on CrazyBike2's DD rear hubmotor now--I can only imagine what that might be like via geared-down chaindrive!

[Samd]

No stress trackman.

If you are into bargain basement stuff, you can make a cheap driver if you wreck a 90 degree head off a junked angle grinder. It'll give you a sloppy but function reduction of about 1:3 ratio to mate to your motor. Then fit a rear freewheel bmx sprocket to the head of the angle grinder where you used to mount the grinding discs. That'll drive your chain. These sprockets can help too http://secure.oatleyelectronics.com//pr ... 4e5ac157dd

It's not a very efficient ratio, but it'll give you a start....

[veloman]

Depends how much you appreciate speed on a bike. Some people expect similar to a motorcycle or car performance. Some are thrilled with going 20mph and not pedaling.

My Mac geared hub motor on 1250watts is a lot of fun to me. Sure, there are times when it's not enough power, but I know the price of going much above the mid 1kw range. The bike itself has a big impact on the fun. A light bike and light battery REALLY helps on non-high power setups.

[dogman]

1 kw can be pretty fun even on a hubmotor if you have the right choice for the job at hand.

But lots of people expect well tuned 50cc motor performance, which is what, 4-5 hp? So they do get dissapointed by 1.25 hp. 1000w will get you to a bike that you don't have to pedal if you don't want to pedal. That's fun enough for many. If you want dirt riding fun, then gear it slow to get up the very very steep hills. You might have more fun geared for 20 mph if you have steep enough hills.

If riding is pretty flat though, gear for 30 mph.

[Punx0r]

1000W is about four times as much fun as pedaling

[ZOMGVTEK]

I was happy with my 48V 1kW Golden Motor rear hub for quite a while. In most every situation, it will propel a cheap bike faster than you can pedal, especially over rough terrain where its difficult to pedal hard.

That said, 10kW+ is many times more fun than 1kW...

[MadRhino]

I heard once, that on a vibrator 1 Kw can be a lot of fun.
First Ebike is good fun no matter the power, next comes the addiction and the need for more.

[Drunkskunk]

My 350 watt motored ebike is F@#$ing awesome!

And its the least fun bike I own. At 3000 watts peak, you're running more power than a moped, and surpassing what a bike is. A 1000 watt motor is fairly large for an ebike. 500w is normal.

Of course, there are some here running much bigger motors. But most are smaller than what you have.

[Kingfish]

It’s a good move up from base. Later, you may wish to push beyond. It took me a while to get used to higher voltage/more power. Eventually I doubled-up to meet my needs.

1 kW will make a good light bike into an excellent climber relative to pedaling.

Enjoy, KF

[Dauntless]

Your not going to see jessus any time soon, but it will be fun if geared right.

How many watts does it take to see Jesus soon, REAL soon???

Fun? Depends on the platform. A Currietech with 350w was to be suffered, a 600w was almost tolerable for me. But I'm 200 pounds with a bum leg living in hills. Then my physically too small Voy Electra at 180w (Hub) turns out to be a bit addicting, still not good enough in these hills and I'm not really up to the pedal assisting it needs.

All sorts of ways to have fun. It would help to comfortable on the Voy, but it's not required. If all you care about is speed, 1kw will never work.

You know that once you do this, you will want more power!!

[motomech]

I heard once, that on a vibrator 1 Kw can be a lot of fun.
First Ebike is good fun no matter the power, next comes the addiction and the need for more.

"Some of the world's most powerful machinery is powered by AA batteries."

[nedfunnell]

Thanks for your input, everyone! The motor I have is a PMDC motor, normal non-hub arrangement. It was originally from a forklift steering mechnism, where it mated to a 43:1 gearbox. Check it out:
http://www.majhost.com/gallery/Ned/misc/big_motor1.jpg
http://www.majhost.com/gallery/Ned/misc/big_motor2.jpg
http://www.majhost.com/gallery/Ned/misc/big_motor3.jpg
http://www.majhost.com/gallery/Ned/misc/big_motor_4.jpg
http://www.majhost.com/gallery/Ned/misc/big_motor_5.jpg
http://www.majhost.com/gallery/Ned/misc/big_motor6.jpg

It is rated for 1-1/3 HP, "Special duty". I think they might have had to made that duty cycle up because it would be very frequently reversing in its original application. I wonder if "special duty" is better than continuous, even. We'll see.

My current thought is to run it through a right angle gearbox and chain or belt drive to the rear wheel. It has a nice thick shaft- once the splines are turned off, probably 1/2". I couldn't use the gearbox from a standard 4.25" grinder (I have two dead ones that I could, if only) because the pinion is too small to accept the 1/2" shaft and I'm not willing to turn it down to 1/4" to make it fit. I have been on the prowl for a gearbox for a 9" grinder, but no luck so far.

Next question: the controller. What controllers would you all recommend? 1000 / 36 = ~28A, 75% efficiency (stab in the dark) makes it 37A. I'd like to have 2X that for surge, so I'll be looking for an 80A controller. Can anyone recommend an 80A 36v controller that can be had for cheap? I have an old Curtis 1505 80A controller, but sadly it's only good for 24v. I thought about running it at 24v just for a little while until I get the first kinks sorted out, and maybe I still will. It'd be a significant power drop. Power is the cube of voltage, right? So at 24v I'd only have something like 300W. I can't remember the formula off hand.

Wild idea: Can I just take an el-cheapo controller and wire up some well-heatsunk high-current MOSFETs were the old cheapie ones were? (probably remotely) Anyone ever tried that? I've been told that the big change in gate charge will really hurt my switching frequency and lose some efficiency. I wonder how much of an effect that would have, practically speaking.

TIA!

[amberwolf]

To the last paragraph: yes, you can. See my DayGlo Avenger thread's early page(s) for some info on that, and more detail on my Electricle blog (which should be linked in those pages to some posts about it).