250w/350w hub motor?

[ammodave]

I see hub motors at many of the ebike sites that list the motor as 250w/350w http://www.greenbikekit.com/index.php/36v-250w-gbk-100f-electric-bike-kit.html. Sorry to be a newb, but what does this mean? Is it 250w or 350w?

 

[motomech]

It's a rating of an electrical device, determined by product liability lawyers/engineers, in China.
Ambiguities + ambiguities + ambiguities = mucho ambiguities

Seriously, it's not a gas engine where it's max. output can be measured and replicated anywhere, anytime without self destruction.
There are variables, how much electrical power is available for it to convert into mechanical energy, under what conditions, for how long.

Actually, that little motor is well known here;
In human comfortable temps, on a human comfortable(reasonably flat)earth surface, one can double the 250W value as a continuous safe number with ocassional bursts up to 750 Watts.

From a practical conceptional standpoint, the gizmos of this hobby are simple.
From a theoretical conceptional standpoint, not so much.

Happy reading , should you so choose.

 

[spinningmagnets]

a watt is a unit of measuring power. 746 watts = one horsepower.

Watts are volts times amps. The amps you feed the hub will make it warmer, and at some point it may overheat. Its ability to shed X-amount of heat is its true measure of power capability. If a small motor is rated to handle 10 amps of power under its reasonably normal loads, then if you hook it up to a 24V system, 24V X 10A = 240 watts. If you use 36V on the same motor, 36V X 10A = 360W. Most motor catalogue power ratings on endless sphere are for 36V and 48V, while using 20A as a starting point.

Typically this is its "continuous load" rating. Almost all motors you will read about can take twice that many watts as a temporary "peak" load. But...since your hills may be steeper and longer than my hills...a certain motor, voltage, and amperage that works well for me might fry when you use it.

 

[d8veh]

The thing you notice most with a motor is how much torque it produces. The more torque, the more powerful it feels, and it's torque you need to pull you up hills and into headwinds. Power has more relevance with motors that drive through the gears, because for them the power determines how fast you go, but a hub-motor you can only realise its power potential if the design parameters match the ride parameters, which isn't often because maximum power is achieved only at one particular speed.

These 250/350w Ananda motors from Greenbikekit are very smooth and quiet, and at 36v with a 15amp controller, they provide a little bit less torque than the 250w Bafang SWX motors with the same controller, but they go really well with 12S lipos at about 48v and 17 to 18 amps, which is about 750w from the battery.

You can make a nice two-wheel drive bike out of those motors. ith two, the bu=ike will climb much better. You can adjust the maximum speed with the battery voltage. 36v for 18nmph, 12S lipos for 22mph, 48v for 24mph.
Here's one I made (use "ctrl" & "-" keys if you can't see the whole photo) :

 

[ammodave]

Thanks for the info. Would this be a good motor for a first build? I'm trying to get 20mph with a 10-15 mi range (level ground) on a bike with a bike/rider wt of about 175lbs using a 36v/10.4ah battery.

 

[-dg]

These 250/350w Ananda motors from Greenbikekit are very smooth and quiet, and at 36v with a 15amp controller, they provide a little bit less torque than the 250w Bafang SWX motors with the same controller, but they go really well with 12S lipos at about 48v and 17 to 18 amps, which is about 750w from the battery.

Since you seem to have tried both, can you compare the Bafang motors, eg SWXK, SWXK5, SWXH or SWXU with the Q100 as far as speed, torque, noise etc? This would be with the 6fet controller shunt modded to between 17 and 22 amps with 12s lipo and all in a 26 or 700c wheel?

I have the SWXK and at 22 amps/48v it seems pretty strong but a little growly under heavy load. I have not really tried anything else yet so I'm trying to collect impresssions for my next build. I'd like to keep it pretty light and stealthy, but I'm on the big side and it is hilly here so I'm concerned that the SWXU and the Q100 may not be up to it.

 

[brumbrum]

Thanks for the info. Would this be a good motor for a first build? I'm trying to get 20mph with a 10-15 mi range (level ground) on a bike with a bike/rider wt of about 175lbs using a 36v/10.4ah battery.

I would recommend the BPM 500w (216bpm version) motor sold by greenbikes. High torque, geared motor so easy pedalling, effcient motor if run at 25 amps and will make about 18-19 mph. I have one and even take it on mtb trails in thick mud and very steep hills and it is great. It was recommened to me by d8veh who has commented above. Will make 15miles with 10ah battery with light pedalling easily.

 

[amberwolf]

more info on watts/etc
http://www.endless-sphere.com/w/index.php/Terminology_and_Explanations_of_Common_Misconceptions

 

[melodious]

Pros of those 250-350 motors: stealth,
Pros of those larger than above motors: upgradability (you can dump more watts into it before it toasts), gives more torque (besides the torque added from your legs).

I do love my small motor. It looks just like my internal geared hub on the rear and gives a symmetric look to the wheels. Also, I feel like I'm contributing to the bike vs. the motor doing everything. However, I realize it has limitations that can only be satiated by a bigger motor.

 

[-dg]

Thanks for the info. Would this be a good motor for a first build? I'm trying to get 20mph with a 10-15 mi range (level ground) on a bike with a bike/rider wt of about 175lbs using a 36v/10.4ah battery.

It sounds reasonable, but I don't know for sure. I can tell you that a Bafang SWXK in a 700c wheel with the 15A controller and 12s lipo at 48 volts has a no-load speed of 27mph and an on road speed of about 22-23 mph (depending on slope, nothing around here is exactly level). It would be more than powerful enough for a 175lb person on flat ground. I built this for my wife who has 3+ miles of 5% grade on her 11 mile round trip and I expect it will work fine for that with 10ah 12s if she pedals most of the time. It is also smooth and quiet, exactly what i hoping for.

At 36 volts it is going to be slower, probably around 18mph or a bit more with some pedaling. 15 miles seems just doable at that speed, but even light pedaling will up that to 20. At least according to the ebikes.ca simulator.

 

[d8veh]

These 250/350w Ananda motors from Greenbikekit are very smooth and quiet, and at 36v with a 15amp controller, they provide a little bit less torque than the 250w Bafang SWX motors with the same controller, but they go really well with 12S lipos at about 48v and 17 to 18 amps, which is about 750w from the battery.

Since you seem to have tried both, can you compare the Bafang motors, eg SWXK, SWXK5, SWXH or SWXU with the Q100 as far as speed, torque, noise etc? This would be with the 6fet controller shunt modded to between 17 and 22 amps with 12s lipo and all in a 26 or 700c wheel?

I have the SWXK and at 22 amps/48v it seems pretty strong but a little growly under heavy load. I have not really tried anything else yet so I'm trying to collect impresssions for my next build. I'd like to keep it pretty light and stealthy, but I'm on the big side and it is hilly here so I'm concerned that the SWXU and the Q100 may not be up to it.

T think you can forget the SWXU because it's not powerful enough. The Q100 doesn't growl like the SWXK/H motors because it runs at higher speed. There's not a lot of power difference, but I think the Bafang has the edge. As I said before, the Q100 can sustain 20mph without pedalling, even up slight inclines at 48v and 17 amps. That's my bench-mark. I can't say how long it would last like that because I normally ride at much slower speeds, so mine are still all OK. The gears aren't as big as the Bafang ones, so they'd probably get damaged more easily; however, they're cheap and it's about 20 minutes work to change the entire core of the motor, so buy a spare motor and have some fun.

 

[-dg]

T think you can forget the SWXU because it's not powerful enough. The Q100 doesn't growl like the SWXK/H motors because it runs at higher speed. There's not a lot of power difference, but I think the Bafang has the edge. As I said before, the Q100 can sustain 20mph without pedalling, even up slight inclines at 48v and 17 amps. That's my bench-mark. I can't say how long it would last like that because I normally ride at much slower speeds, so mine are still all OK. The gears aren't as big as the Bafang ones, so they'd probably get damaged more easily; however, they're cheap and it's about 20 minutes work to change the entire core of the motor, so buy a spare motor and have some fun.

I'm not trying to be contentious, but searching here and at pedelecs.uk about the SWXU only finds a post from you saying that you ordered an SWXU but it would not fit with your disk brake so you passed it on. My question is, have you actually compared the SWXU and either SWXK or Q100 in a bike, or is "forget the SWXU because it's not powerful enough" more of an estimate based on the size.

My goal is to be able to sustain a 6% grade with about 100 watts of pedaling or a bit more in a 20" wheel at 140kg all up. I'm currently leaning toward the 201 rpm SWXU at 52v with the Q100 in 328 at 45v as an alternate.

Your point about buying an extra motor to have a spare core is a good one. Does the Q100 come apart without special tools?

 

[motomech]

The Cute comes apart easily w/out special tools.
The 201 Bafang is too slow a wind for a sm. wheel.
The Q100 rear will take a 8 or 9 T. free wheel if that is important to you.
Although I like the MXUS mini best, the Q100 is a slick kit for the money.
You can read about my experiences with both, link below.

 

[-dg]

The Cute comes apart easily w/out special tools.
The 201 Bafang is too slow a wind for a sm. wheel.
The Q100 rear will take a 8 or 9 T. free wheel if that is important to you.
Although I like the MXUS mini best, the Q100 is a slick kit for the money.
You can read about my experiences with both, link below.

I have read your build threads with interest at least twice through. They were informative and inspiring.

The priority for this Xootr Swift folder build is to keep the weight minimal and balanced front and rear because I have to carry the bike up and down multiple flights of stairs at the transit stations. It will be front drive and I'm planning to carry only 5 or 6 ah of lipo so the wh per mile has to be pretty low to get sufficient range. Target weight is under 40 lbs all up including my laptop. The primary goal is to get me to client meetings without getting too sweaty although I will pedal. I can ride home unassisted if I run out of battery although it would be nice to have a little left over.

I think the 201 wind is about perfect for this assuming my calculations are correct and that the 201 SWXU is the same unloaded speed as the 201 SWXK. Please let me know if I'm missing something here:

201 rpm SWXK in a 27" wheel and at 45 V (12s nominal) gives 24.5 mph unloaded and 21 mph loaded with light pedaling. Assuming the SWXU 201 wind is the same rpm as the SWXK 201 wind then:

21mph * 20" / 27" = 15.3 mph [smaller wheels] and 15.3 mph * 14s/12s = 17.9mph [higher voltage].

So a 201 SWXU in a 20" wheel and 14s lipo should go about 18 mph or better (at higher state of charge) with a little pedaling.

To get the range I want with only 260 wh of battery I will have to keep the speed under 20 mph so this works out pretty well. If it went faster I'd have to throttle back to keep the speed down anyway. I wish I knew for sure if the SWXU 201 really is the same speed as the SWXK 201.

I suppose the Q100 201 wind is another possibility, but I'm unclear on what the advantages would be over the 201 SWXU.

 

[d8veh]

T think you can forget the SWXU because it's not powerful enough. The Q100 doesn't growl like the SWXK/H motors because it runs at higher speed. There's not a lot of power difference, but I think the Bafang has the edge. As I said before, the Q100 can sustain 20mph without pedalling, even up slight inclines at 48v and 17 amps. That's my bench-mark. I can't say how long it would last like that because I normally ride at much slower speeds, so mine are still all OK. The gears aren't as big as the Bafang ones, so they'd probably get damaged more easily; however, they're cheap and it's about 20 minutes work to change the entire core of the motor, so buy a spare motor and have some fun.

I'm not trying to be contentious, but searching here and at pedelecs.uk about the SWXU only finds a post from you saying that you ordered an SWXU but it would not fit with your disk brake so you passed it on. My question is, have you actually compared the SWXU and either SWXK or Q100 in a bike, or is "forget the SWXU because it's not powerful enough" more of an estimate based on the size.

My goal is to be able to sustain a 6% grade with about 100 watts of pedaling or a bit more in a 20" wheel at 140kg all up. I'm currently leaning toward the 201 rpm SWXU at 52v with the Q100 in 328 at 45v as an alternate.

Your point about buying an extra motor to have a spare core is a good one. Does the Q100 come apart without special tools?

You're correct. I didn't actually try it. I took one look at it and could see that it was very small. If you have a look at the Bafang website, where they have the specifications, you'll see that it's only rated at 180-220w compared with 180 - 250w for a SWXK. We need a volunteer to test one and see exactly what it can do, but my expectations wouldn't be high.

You can open a Q100 with a hammer and a screwdriver (literally) without damaging it.You just screw a 6mm screw into one of the three clutch retention screw holes and tap it round anti-clockwise. You can then unscrew the side-plate, which brings out the whole core with it. At $79 for the whole motor, it's worth getting one for spares so that you can over-drive your first one without worrying that your bike will be off the road if the motor smokes. The only failures I've heard of with the Q100 is when they've been run at more than 20 amps, although I've had and heard of at least one other 328rpm versions that appear to have starting problems, so, until I've found out why, I'll stick to over-volted low-speed versions.

 

[motomech]

I have never ridden a folder w/ 20" wheels, but from the perspective of a full size bike rider, limiting yourself to 17-18 mph is too slow.
The fun starts in the low 20's.
But I looked at the bike you are going to convert and staying below 20 mph seems like a good Idea, in which case, going with a slow wind seems correct.

As for the motor size, staying with the sm. 2.2 Kg. mini also seems like a good idea.
For the 2.2 Kg. size, it's the SWUX vs. the Cute. To me, this is a no brainer, go with the Q100, which a number of us run 17 Amps though it @ 12S, where it is very happy.
If I were starting from scratch, I would try Stephen Dang @ Elifebikes. I have been communicating with him and he always gets right back to me.
But the reason I would go with them over BMS Batt. is this controller;
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2012-7Q-P96D.9KNYX
17Amps and a 42V LVC, which is perfect for your build. With your limited capacity of Lipo, you really are going to need a solid LVC, which the BMS controllers do not provide. You could ask him to swap in that controller w/ this kit;
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2011-43-GR8W.234ME
or just buy it outright($17).

But as I look at the folder, I seems to me the the Lipo is going to have to go up frt. somewhere, perhaps in a h.bar bag and that is going to bias the center of gravity to the frt., both folded and unfolded.

So, what I think I would do is go with the rear cute kit.

http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2011-43-GRTP.234JT

As I mentioned before, one of the advantages of going with the Cute over the Bafang, is the ability to mount a 8-speed freewheel, which would match the Swift's shifter. Calculate the gearing for your projected top speed to see if you need the DNP 11T free wheel or if the much lighter 13T options will work.

As for motor no-load speeds at 36V, the Q100 "201" is 230 RPM, while I am pretty sure the Bafang 201 is really 201 RPM, so the cute might have a mile-an-hour or so over the Bafang.

That's the way I would convert the Swift.

 

[-dg]

You're correct. I didn't actually try it. I took one look at it and could see that it was very small. If you have a look at the Bafang website, where they have the specifications, you'll see that it's only rated at 180-220w compared with 180 - 250w for a SWXK. We need a volunteer to test one and see exactly what it can do, but my expectations wouldn't be high.

Well, maybe I'll be that volunteer , partly because I'm pretty pleased with the SWXK and partly because now I'm curious. If someone wants to loan me a 20" Q100 wheel, I'll definitely get an SWXU to test against it.

Funny thing about the size, I had a look at the dimensional drawings of the Q100 and the SWXU and they are almost identical. Spoke hole diameter is 108mm on both, both fit a 100mm fork with not much room to spare. The flanges are either 42 or 47 mm apart for the Q100 and 45mm apart for the SWXU. Claimed weights are 2.0 kg for the Q100 and 1.9 kg for the SWXU. They lace up with the same spoke lengths. Internally of course they are very different.

One last thing, is anything negative known against the SWXU? I imagine they have a bunch of them outside the US due to the power restrictions so I suppose if they were rubbish we'd have heard about it by now.

 

[toniovelo]

You can make a nice two-wheel drive bike out of those motors. ith two, the bu=ike will climb much better. You can adjust the maximum speed with the battery voltage. 36v for 18nmph, 12S lipos for 22mph, 48v for 24mph.
Here's one I made (use "ctrl" & "-" keys if you can't see the whole photo) :

[/quote]

For the 2wd q100, what is the max amps for each q100 you put inside ??? 10amps for each is good with a 48v battery? thanks!