E-Bike Rear Hub Motor around 3kw

[sigimem]

Hi

nice to find such a forum finally .
Since this is my first post i should introduce myself a bit. My name is Dennis 25 years old Student and a bike enthusiast (with and without engine) like most people here. I live in the southwest of Germany (hope that will explain mistakes in writing ). I'm good informed about mechanical things and problems but i have a great lack when it comes to any electric knowledge so i hope you might help me out?
I'm planning on building an eletric bike from scrap in long term. Since this a (very) long term project I want to use a normal downhill frame first to test the motor handling and so on.
Specifications for the bike are: 2.5-4kw Rear Hub Motor, 40-60 km/h Topspeed, max 40 kg weight, Range of min. 40 km,

I thought about using a Crystalyte HS 3540/3548 Motor running it on 72V with 40 A output I found this Motor in a kit here http://www.ebikes.ca/store/store_nc.php what do you think about this motor? Does it get to hot running in that configuration(how long does it take?)?
Wich kind of battery pack and controller would you recommend? thought about using Lipo batteries but since I didn't found any 72V packs in the right capacity yet it might be a problem (afraid of the risks when assembling 2 36v myself). Sorry for beeing such a noob :?

sigimem

 

[rjoe]

you can use the simulator on ebikes.ca to find out when the motor would overheat

 

[sigimem]

thanks a lot didn't see that
I thought the HT Motor has a Topspeed of 25 km/h und doesn't go faster with more current?

 

[dogman dan]

More volts will make a motor spin faster. More current at the same volts will make it pull harder, or if stalled, make more heat.

You should be able to get 10 miles of riding full throttle before that motor heats to the melting point. Less, into wind, up hills, or on a track with tight corners.

Temperature sensors are what you need to know where the motor heat is at any moment. BBQ thermometers are the common type used to add one on the stator.

Experiment with something affordable, either the H model crystalyte or the 9 continent motor. Then when you have some stuff figured out, ( like torque plates) build your real bike using a cromotor ( greyborg), or 5400 series clyte and lipo batteries.

If you are happy enough with more like 2000w, you can go a lot longer with the cheaper motors.

The cheaper motors can tolerate 3kw, But only for short periods, 20 -30 min. Less under some conditions.

A cycleanalyst is not a mandatory thing, but when you get one you will dope slap yourself for not doing it sooner.

Can't lose doing buisness with ebikes-ca. Best Ebike kit vendor worldwide. Inventor of the CA, and many other improvements that china could care less about.

 

[sigimem]

Thanks a lot for the good advice.
Do you know wich motor stealth electric bikes from australia uses for their Fighter? Cause It seems to get along with 3 kw?
I havent riden a real E-bike yet but I hope to get along with 2-3kw pretty good especially when its not too heavy.

 

[dodjob]

Servus Sigimem,
Like it was said using a Cycle Analyst is a must. There is tons of advantages inherent to it's use
Concerning your project. What do you intend to do with your ebike? mostly offroad? If it's the case please consider the weight of DD motors.
I'm using a MAC motor 1000W with the new gearing and a 12 Fets controller from cell_man with 48V lifepo this configuration is quite good and VERY torquy ^^ and max speed about 60Km/h
You should really try a real ebike before statuate on the power you need. I mean it's really crazy to see how hard a "little" 1000W geared motor with right controller and batteries can pull in comparison with our standard ebikes "auf 250W runtergedrosselt"
Gruß,
H.

 

[sigimem]

Yes its planned for Offroad use for about 80% of the time. I might use it for riding around in the forest instead of my old 250 mx bike (from time to time) that might also be the reason for me wanting slightly more power.
Your totally right I should really test a real ebike before putting too much power and weight into it. How heavy is your Motor btw?
But at least i figured out that "auf 250W runtergedrosselt" pretty much sucks . But It would be nice to have some kind of switch or so for that 250W mode.

 

[dodjob]

Sers,
the mac motor weight about 4,5Kg. If you send me your email adress in PM I can send you a pictures a good friend of mine has made of his bike
don't be that much stressed about the 250W limitiation. Die Polizei will only check the max speed if they ever want to check something.. And this is easily setable on the CA
Gruß,
H.

 

[dogman dan]

Since you are aiming for offroad use, pay lots of attention to what Mad Rhino says. I do some off road riding too, but my style is more slow so my solutions may not be for you. Being slow, I don't require quite as good suspension. I focus on being able to creep up steep hills without overheating.

I have some stuff on Y tube. This is what a slow dirt ebike rides like, 25 mph max.

http://www.youtube.com/user/Dogman5018?feature=mhee#p/u/11/AfwdkfNZ7RQ

 

[MadRhino]

The right choice for you is all about where you ride and how fast you want to be.

Dogman's bikes are great for steep technical riding where you can't ride fast, and this is a particular situation that can fry a fast setup in no time. For this purpose you need to build the bike to run in its high efficiency curve at lower speed.

If you are a fast off road rider, the H series motor is a good choice. It can deliver a lot of power and speed for its light weight. I have 2 of them here that I run at 100v, feeding bursts over 7 Kw, and they rock. This motor, like any other that is light weight, can overheat pretty fast when it is running outside of its efficiency speed range. My setup is very fast, so I need to monitor heat when I have to slow down in technical trails, which I can't ride very long before endangering the motor. My solution is to swap various motors according to trail conditions: I use slower winding, bigger motors when the trails are slow, and the light weight fast motors for the nice days when I can speed at will. I like the H series motors because their light weight makes it possible to achieve proper suspension tuning, without any major loss of power. The heavier motors are a compromise, they stand the heat much better but the ride quality is affected.

Using Lipo is not complicated, and they offer the light weight and power needed for a good off road build. They can be charged fast, and that makes for an even lighter setup if you ride short distances and can recharge between laps. You need to learn about Lipo safety care, and set a safe charging place, apart this inconvenient they are the best solution.

Good luck with your build.

 

[sigimem]

That speed guess might be the problem. I live in a hiking region exactly between two valleys wich is really nice but you have to go up und down a lot sometimes steep hills for 5km. I will discribe it that way when i ride with the mx bike i mostly go between 20 and 50 km/h which would be really nice to do it with an e bike. (I wont sell the other one anyway so the e bike doesn't need to be that fast).
@MadRhino wich motor do you use for the more technical terrain? and how fast do you go with it?