recommendations for these requirements?

[callagga]

Hi,

I'm having a dilemma deciding between hub motors for a 36V system. I do a 2 x 18km commute with a few hills. I average say 20-25km/hr on the flat, around 10km/hr when climbing the hills I have, and down hills like to approach 50km/hr (head down / no pedaling). Overall I really want to do all the work myself during my commute (2 x 18km) for on the flats & downhill (going fast downhill), and have the hub motor then to get me up the hills more quickly (and reduce my effort here). Having not ridden an electric bike this would seem to imply one of the most import things would be to avoid ALL drag from the motor when moving the bike along by mostly pedal power (or running downhill).

QUESTION 1: What would you recommend re hub motors? I was thinking of:

(a) Crystalyte 408 hub motor,

however I've read that non-geared (direct drive) hub motors having a "cogging torque"/"motor drag" when not using electrics. This would apply to the Crystalyte 408 hub motor then? In which case should I be considering:

(b) eZee brushless hub motor perhaps? However are these more noisy than the non-geared?


QUESTION 2: What happens on both of these motors when you go past the speed when torque drops to 0?

Do they give you drag at this stage? Is there any reason to go for one or the other of the models here? I'm trying to understand I guess with hub motors what happens when (a) you pedal the bike faster than it's rated maximum (i.e. where torque hits 0), and as well (b) when you have electrics switched off for the flat and (c) when you have electrics on but you're going down a hill fast but not pedaling. That is for which case does either the (i) non-geared or (ii) geared motors impede things by having resistance that comes to bear...


Thanks



Thanks
Greg

 

[dogman dan]

From what you describe, the ezee is what you want. I've not ridden one, or even actually seen one ridden but the noise is said to be not all that bad. You won't hear this noise when not under power, so it would only be heard when ascending a hill. I have a metal gear motor, a heinzmann, and at some speeds the noise is very annoying. That motor is usually rated pretty dang noisy by people. To see what it will feel like, load up the bike with the weight of the kit, and go riding. I'm not sure what the kit weighs, but 3 gallons of water ought to do it. Maybe 2 gallons of sand? two sacks of potatoes? something like that.

On the cogging, I found cogging real bad on my brushed motors, but I barely notice it on my newest motor, an aotema brushless similar to a 407 or 408. But I wouldn't want to pedal powerless with all the hub kit weight, cogging or no cogging. If your ride has rolling hills, you could easily ride powered up them and unpowered down them on a direct drive. But in my opinion, riding any real distance on the flat with the motor kits weight would be no fun with either kind.

My brushed hubs provided significant resistance that made steep descents less fast, which was nice. The new brushless aotema does too, but not near as much. I find with cogging, it gets hard to push a motor much faster than the amps you have are giving it. I have a real tall gear, and could add 10 mph by pedaling hard, but above about 3-4 mph more than a motors top speed, I start to feel a lot of resistance to going faster on flat ground. Honestly, I haven't tried to add speed when going down a steep hill, so I don't know about that.

For the least resistance, again, the gear motor is the ticket. When the throttle is not applied, it rides with zero resistance except for the weight added. There is a huge difference between riding unpowered on my gearmotor and on my direct drive motor. The gearmotor will really coast, the direct drive will start slowing right away.

 

[Brainersan]

And as long as we are on this topic, Dogman, could you help to clarify the impact of a few things? I still don't get all the inter-relationships, completely. So let's say we go with an eZee geared kit, 10ah controller.
1. Swap out the 36v and replace with 48v - what should we expect on exactly the same route, same conditions, same rider? I believe range would be extended. Anything else of note?

2. In either configuration - all things being equal, let's say we upgrade the 10ah to 13ah - what are the results? Then go to 18ah - in other words as these numbers go up, what is the result?

As I have spent time looking at various configurations I am far less concerned about the motor. If I make a bad choice or smoke it somehow - it's not super costly to replace. However, batteries seem to be the big ticket/smart choice item. I guess I can't see why I would not just go with 48v to provide the most oomph and coverage - bigger is better mentality. Am I off base on this? Thanks for any info.

Finally - I keeping seeing references to LiFpo stuff - what is this??

 

[dogman dan]

Lifepo4 is lithium iron phosphate. Written in the periodic chart symbols, Li-Fe-P-0 and the 4 is how many oxygen molecules in phosphate, PO4.

It's the newer lithium battery chemistry. It's a bit safer than the older lipoly type that used to catch laptops on fire when charging. Lipoly has also improved, so that may be history already. All the many lithium battery types, share the light weight which makes big capacities easy to carry. In lead batteries, 10 miles of range weighs 30-40 pounds. In lifepo4 10 miles of range weighs maybe 8 pounds. So it's the bomb for ebikes. Lifepo4 cells can last 1 or 2 thousand cycles too, where lead acid is doing great to go 300.

Given the theoretical lifespan of a good lifepo4 pack, it becomes a choice that could go through several motors. Get back to me in two more years about the real lifespan, when I have 10,000 miles on my pingbattery, or not as the case may turn out to be.

I see you have a bit of confusion already, on controllers and batteries.

Ah, is amp hours, a way of measuring the size of a battery. Some chemistries, like lead acid, can't even put out the whole rated ah on a bike, while others like lifepo4 can put out almost 100% of the rated capacity on a bike. The reason is peukerts effect, see the tech section for definitions and stuff on that or anything else that is greek by now.

Controllers have an amp rating, Amps is just a rate of power flowing out of the battery. A higher amp controller is allowed to suck the battery dry faster than a lower amp controller.

Amps x volts is watts, watts is the true measure of a motors power, so that's the number sellers love to exaggerate.

Take a 20 amp 36v controller. On such and such motor, this controller at full speed on flat ground draws say, 12 amps. The 36v battery may actually be putting out 42 v in the real world x 12 amps = 504 watts , real world, power used at cruising speed. That's the number we want to know usually.

But the same controller, 42v x20 amps = 840 watts. I can sell more of, and price higher this motor.

And the same contoller, for a half second or so, will put out even more than 20 amps, while starting up. so lets just call it a 1000 watt motor

This makes comparing paper statistics on motors really hard, and why Justin has the simulator on his website.

Changing the voltage, does two things, it gives a higher wattage with the same controller, so more power and usually speed. Sometimes if the controller is not made for 48v, the controller goes poof and stinks up the garage. In the same size in amp hours, a 36v battery is 25% smaller than a 48v. So range increases simply because you are now carrying more battery.

Back to the question, I'll try to answer both at the same time now. Ah of the battery and amps of the controller, as used on a given motor, need to be matched well. Too many amps and too few ah and you get a lot of strain on the battery, with bms controlled lithium batteries, they may shut themselves down at bad times. The real issue is the capacity of the battery to supply amps at the rate the motor wants it. Different batteries have different ability to supply it. High c rate batteries can supply more amps in a smaller ah size than a lower c rate battery.

C rate is a way to say how fast a battery can be drained. A 10 ah battery with a 1c rating can supply 10 amps. Rated 2c the same battery can supply 20 amps.
So the size, c rate, and how many amps the motor wants have to match to have it work on the long haul.

When talking about the pingbatteries or other duct tape wrapped lifepo4, you often see me say either, get the 20 ah size, or get a different battery depending on the motor used. I just think big range, and discharging at low c rates are good things, a 20 ah battery can discharge 20 amps at 1c, and that is a rate that should not damage the battery, and can run most of the motors on the market.

 

[Brainersan]

Great, thanks for taking the time to type all of that! Very helpful.

 

[dogman dan]

The more times I explain stuff, the closer to having it right I get :lol:

 

[JinbaIttai]

. . . Overall I really want to do all the work myself during my commute (2 x 18km) for on the flats & downhill (going fast downhill), and have the hub motor then to get me up the hills more quickly (and reduce my effort here). . .

For a hub motor:
-On the downhill you can coast/hold it at zero throttle/pedal with the switched turned off even. Chances are that the top speed of the motor is slightly faster than the tallest gear combo on the bike anyways, so in order to pedal faster than that, you will be doing a cracked out hamster on the wheel impression.

-On the flats you can pedal while holding the throttle in that exact spot that feels just like you're riding a bike with no motor. Or give it a touch more throttle so it feels just like you're riding a bike with no motor with the wind at your back. Or you can give it a touch more throttle so it feels like you're riding a bike with no motor, with the wind at your back, and with the feeling of a slight down grade...Wanna coast for 60 seconds or maybe 5 minutes? Give it a touch more throttle, no need to pedal anymore.

You really should try a hub motor at 36V. 24V is way too anemic of a test.

I'm happy with my ampedbikes hub motor. It is more efficient than a 408.

 

[callagga]

thanks - So far from the about 4 responses (here and via email) all suggest the geared motor (e.g. eZee) would be a better choice than a gearless, for my requirements (as it does seem you get more of frictionless freewheeling on the geared on the flat/downhill when not using electrics).

Is there someone who has owned both a geared (like the Crystalyte 408) and a gearless (like the eZee) who can confirm this?

More info for my ride if this helps.

• 19km each way
• Ride time (1 way) = 55minutes
• Max speed = 50km/hr (down hills)
• Average speed = 21km/hr
• Speed when climbing hills 8km/hr - 12km/hr
• Example of worst hills is a 30% for a couple of hundred meters

 

[morph999]

And as long as we are on this topic, Dogman, could you help to clarify the impact of a few things? I still don't get all the inter-relationships, completely. So let's say we go with an eZee geared kit, 10ah controller.
1. Swap out the 36v and replace with 48v - what should we expect on exactly the same route, same conditions, same rider? I believe range would be extended. Anything else of note?

2. In either configuration - all things being equal, let's say we upgrade the 10ah to 13ah - what are the results? Then go to 18ah - in other words as these numbers go up, what is the result?

As I have spent time looking at various configurations I am far less concerned about the motor. If I make a bad choice or smoke it somehow - it's not super costly to replace. However, batteries seem to be the big ticket/smart choice item. I guess I can't see why I would not just go with 48v to provide the most oomph and coverage - bigger is better mentality. Am I off base on this? Thanks for any info.

Finally - I keeping seeing references to LiFpo stuff - what is this??

I've been told that you can get almost the same speed with one of those cyclone motors with 24v as you can with 48v of hub motors. I guess the only drawback is that a lot of people say that the cyclone motors can't sustain the speed for very long while you full throttle the hub motors for hours.

 

[morph999]

I think Russell owns a BMC geared motor if you want to ask him what it's like. For 19km, you'll definitely need a 48v20ah lifepo4. I can't say for sure you'll probably find that over time you prefer to use the electric motor to get you where you need to go. It's just so much more fun and it can go twice as fast.

 

[dogman dan]

I can. I own a direct drive aotema that I ride 30 miles when I commute to work on it. With a big battery and plenty of range, I mostly ride wide open throttle at 20-25 mph depending on uphill or down. But at times, for whatever reason, I have had to make it stretch. I can get 2 miles out of almost no power at all if I just use a tiny bit of throttle and pedal. Just enough to go about 4 mph will eliminate the cogging and make it easy to pedal at about 8 mph. Trying to pedal faster that that without more throttle, and you will hit cogging resistance and feel it. To me it feels like the more you want to exceed a certain speed the more you feel the cogging. I've heard unplugging the motor from the controller helps, but I can't feel the difference since with my new motor, cogging is not so bad.

My dirt bike, an EV Global with a geared heinzmann motor rides different like night and day. Don't get me wrong, this thing is a bear to pedal with 2 sla's on board and a heavy motor. But with the freewheel in the motor, you can goose it to top speed, only 13 mph, then pedal to about 15 easily, since there is no cogging, 15 is the top for this bike because of gearing, but on another kind of bike you could pedal to the speed of your choice. Then it will coast a long way if the road is flat. I'd say it would coast 3-5 times farther than a dd motor. Then you repeat the process, motor some , pedal some , coast some. If it's slightly downhill, even just a bit, you might just pedal easily for quite some ways. In any case, the bike can be ridden using the motor only 1/3 of the time if you want to , without a huge effort.

So the gearmotor is more effiecient right? Yes and no. In my case my gearmotor is a pretty inefficient brushed motor, while the non gear is a very thrifty brushless motor. Ridden at the same speed, the non gear is pretty efficient. The sla's in the gear bike are definitely no help either. In my case they both use about the same amount of power per mile. A brushless gearmotor may be a different story, but there is some energy lost in the gear train, but I think it could be made up for by the coasting.

Bottom line, the really crazy long ranges reported by owners of motors are from gearmotors, since they can simply pedal farther without power and use the motor only when going uphill. That won't cut it for me on my long commute, so I just use a direct drive and zoom with a big battery. I just don't want to spend 3 hours on the commute, when I can get it done in 2 with a dd motor. Personally, even though a big battery is very expensive, I think the dd is the way to go, and if you need really long range, you can ride slower and get more range that way.

 

[callagga]

thanks dogman (that's was exactly what I was interested in)

I'm wondering overall if the summary for my requirements would be something like:

* Option 1 - Geared => Lighter bike (not as large batteries), as I wouldn't plan to use throttle on flat/down hill (i.e. acknowledge sweat work still required), will offer more help on the steep hills however than the non-geared

* Option 2 - Non-Geared/DirectDrive => Heavier bike (i.e. with larger batteries), but then plan to use throttle to some extent most of the way, more effort required on steep hills than geared


Am I on the mark?

 

[dogman dan]

I'd say so, but the battery weight may not change much depending on how much you spend. There is, on the lower c rate lifepo4, a certain minimum size to supply enough amps for the motor, 10-15 amp hours is usually enough for most moderate wattage motors. The tool pack batteries , a 123's and lipoly can be much lighter with the high c rates they can supply. 10 ah will be plenty for 18 k of riding with a direct drive motor. So the gear choice may end up only 5-7 pounds or so lighter. That is a lot of weight on a regular bike, but on an ebike, 5 pounds is not much to worry about with all that power in the hub.

But yeah, a bafang gearmotor and 4 ah of high amp rate lithium can be about 15 pounds lighter than a direct drive motor and a 15 llb, 36v 20 ah lifepo4 battery.

 

[Russell]

A Bafang geared hub motor with a lithium battery sounds like a good solution for you. You can read about my bike here to see if you'd like to build something similar:

http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=8579


It weighs 52 lbs fully equipped and pedals very much like it did before the conversion, just 16 pounds heavier.

-R

 

[callagga]

A Bafang geared hub motor with a lithium battery sounds like a good solution for you.

Is there a reason you'd recommend this over the eZee?

 

[Russell]

A Bafang geared hub motor with a lithium battery sounds like a good solution for you.

Is there a reason you'd recommend this over the eZee?

Only if you're on a budget, otherwise go for the more powerful eZee or BMC.

-R

 

[callagga]

I see the Bafang is rated at 750 watt - 36 volt, that's reasonably powerful isn't it? In fact should they really rate a motor with a Wattage, as does this just depend on your voltage system you connect up to it? Is there torque versus speed curve for it somewhere?

 

[Russell]

I see the Bafang is rated at 750 watt - 36 volt, that's reasonably powerful isn't it? In fact should they really rate a motor with a Wattage, as does this just depend on your voltage system you connect up to it? Is there torque versus speed curve for it somewhere?

How motors are rated depends who you are talking to. My Bafang is rated at 250W however since the controller allows 15A it will draw around 550W-peak from the 36V battery. When I used a 22A controller with the motor and a 6V SLA booster I was seeing in excess of 950W. It's not a real powerful motor putting out perhaps 20 N-m of torque for a 36V/15A system but it accelerates fine because of the gear reduction. If you want to push the little motor to higher speeds and currents it will definitely boost its performance but you should change out one of the nylon gears for a metal one. The only real beef I have with my Bafang is it vibrates under heavy load. I tightened the spokes which quieted the rattling the vibration caused but I still feel it through the handlebars. Whether this is common or not I can't say.

The real appeal for the Bafang is its cost with the motor maybe 1/3 the price of the premium geared motors. However since a lithium battery is often the biggest expenditure in the end the difference between a Bafang and an eZee kit seems less. For example Cycle9.com sells a 36V "8FUN" kit (just another name for a Bafang) with lithium battery and rack for $899 and an eZee kit with lithium battery and Schwalbe tire for $1235, not a huge difference. it's possible to piece together a Bafang system (w/lithium) for less but not a lot less.

The Bafang motor is a good choice however for those riders who simply want some assist and will ride at normal recreational speeds (under 30 km/h). I use mine to supplement my input which means I can get a good workout but not kill myself on hills or into strong headwinds. If you have the money to spend though I'd skip the Bafang and go for the eZee kit or the BMC. The eZee kit is also nice if you want something you can install easily and ride and not worry about lacing up wheels or matching components.

Bottom line is if I could go back and tell myself what to buy I'd get the eZee. Of course I would not have had as much fun along the way

-R

 

[callagga]

I'm narrowing in here

Is the BMCv1 just as good to get as the eZee? What would be the difference between them?

(I don't see the BMCv1 on the http://www.ebikes.ca/simulator/ simulator)