Go Back  Bike Forums > Bike Forums > Electric Bikes
Reload this Page >

350w, 500w and 750w motors. What is the difference?

Notices
Electric Bikes Here's a place to discuss ebikes, from home grown to high-tech.

350w, 500w and 750w motors. What is the difference?

Old 03-21-17, 09:09 AM
  #1  
M2faux
Senior Member
Thread Starter
 
Join Date: Mar 2017
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
350w, 500w and 750w motors. What is the difference?

I'm trying to understand the difference between the three different size motors? Is there a difference?
M2faux is offline  
Old 03-21-17, 09:30 AM
  #2  
kickstart
Senior Member
 
kickstart's Avatar
 
Join Date: Feb 2014
Location: Kent Wa.
Posts: 5,332

Bikes: 2005 Gazelle Golfo, 1935 Raleigh Sport, 1970 Robin Hood sport, 1974 Schwinn Continental, 1984 Ross MTB/porteur, 2013 Flying Piegon path racer, 2014 Gazelle Toer Populair T8

Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 396 Post(s)
Likes: 0
Liked 2 Times in 2 Posts
Originally Posted by M2faux View Post
I'm trying to understand the difference between the three different size motors? Is there a difference?
It's basically a way to quantify an electric motors rated potential power output.

350W = .46 HP,
500W = .67 HP
750W = 1 HP

Last edited by kickstart; 03-21-17 at 09:35 AM.
kickstart is offline  
Old 03-21-17, 09:50 AM
  #3  
M2faux
Senior Member
Thread Starter
 
Join Date: Mar 2017
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Volts x Amps = watts.
(( Less power loss ))
That's why I see 15amp controllers on Ebikes with a 52v battery.
52v x 15amps = 780watts (less powerloss thru the solder joints)
That's a lot of power. Watching the video that KingCat just posted was impressive.
My friend rides a Bromptom with a 250w motor. But he just installed a 52v battery and I know he has a 15amp controller. PAS only. He put well over 15,000 miles on his 250w motor. I'm sure he'll get another 15,000 miles easy .
M2faux is offline  
Old 03-21-17, 04:44 PM
  #4  
2old
Senior Member
 
Join Date: Jul 2014
Location: socal
Posts: 2,318
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 393 Post(s)
Liked 165 Times in 120 Posts
Theoretically, the watt rating of a motor is the amount of power that it can withstand and run indefinitely. Of course, many motors can take much more power for short periods of time and many are grossly underrated. I have a 48V, 1000w system with a 30 amp controller and 52V battery (58.8V hot off the charger). I've never noticed it even getting warm.
2old is offline  
Old 03-21-17, 10:48 PM
  #5  
M2faux
Senior Member
Thread Starter
 
Join Date: Mar 2017
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Nice. Over engineered is the way to go. I'm also hearing different stories now from my friends that ride local. The higher watt rated motors with lower "kV" wind go up hills with less pedaling required but are not as fast on flat terrain.
M2faux is offline  
Old 03-22-17, 06:02 AM
  #6  
Robert C
Senior Member
 
Robert C's Avatar
 
Join Date: Sep 2006
Location: Kansas
Posts: 2,163

Bikes: This list got too long: several ‘bents, an urban utility e-bike, and a dahon D7 that my daughter has absconded with.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 324 Post(s)
Liked 15 Times in 14 Posts
I have a 350W geared front hub motor on my commuter and a 750W Mid drive on another bike. I keep the the 350W set to 5/5 on the controller and th e750W set to 1/5 on its controller. As such, they are generally pulling about the same amount of power, in the range of 100-20W.

Based on this I see that the mid drive, even when set to the lower power level, feels more powerful, as an effect of using the "gears" (it is going through a Nu-Vinci, so there really aren't gears, just a crank, sprocket, and transmission).

Clearly, I could have used a 350W mid drive, for my purposes. As was pointed out, the difference, all other things being equal, ceteris paribus, the 750W motor will have more power available. If you are planing to use it on a utility bike, for things like groceries, passengers, and frequent trailer pulling, then you may want a larger motor. For commuting, a smaller motor may be more appropriate.
Robert C is offline  
Old 03-22-17, 10:34 AM
  #7  
M2faux
Senior Member
Thread Starter
 
Join Date: Mar 2017
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks for your input Robert C . Can you post a pic of your 750w Ebike?
M2faux is offline  
Old 03-22-17, 11:49 AM
  #8  
Robert C
Senior Member
 
Robert C's Avatar
 
Join Date: Sep 2006
Location: Kansas
Posts: 2,163

Bikes: This list got too long: several ‘bents, an urban utility e-bike, and a dahon D7 that my daughter has absconded with.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 324 Post(s)
Liked 15 Times in 14 Posts
Originally Posted by M2faux View Post
Thanks for your input Robert C . Can you post a pic of your 750w Ebike?
Here it is, loaded for touring:
Robert C is offline  
Old 03-22-17, 01:27 PM
  #9  
chas58
Senior Member
 
chas58's Avatar
 
Join Date: Jul 2010
Location: Michigan
Posts: 4,337

Bikes: too many of all kinds

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 976 Post(s)
Liked 223 Times in 179 Posts
oh, so much to say.

If you are regular biker, you can probably put out 200+ watts. I do 200-300 in a steady state, so a 350 watt motor basically doubles my power. Its a lot like riding a tandem with my brother. Its fun, but not OMG!
a 500 watt bike accelerates like I do when I'm sprinting at full power.

for moderate current:
350 watt = 36 volts
500 watt = 48 volts.
750 watt = 48 volts and more current (or less likely, 36 volts and lots of current).

roughly speaking
voltage = speed
current = torque (pulling power).

750 is the legal limit in the US, because that is 1hp - and anything above that is classified as a moped.

FYI - it seems that the steady state draw from a controller is about 2/3 of its rated max current. Thus the 15 amp controller your buddy uses likely draws something like 10 amps at the cruising speed and 15 amps under acceleration (with a proper design, the motor will hit top speed significantly after the controller has hit max current, and is on the downward slope of power output).
chas58 is offline  
Old 03-22-17, 01:33 PM
  #10  
chas58
Senior Member
 
chas58's Avatar
 
Join Date: Jul 2010
Location: Michigan
Posts: 4,337

Bikes: too many of all kinds

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 976 Post(s)
Liked 223 Times in 179 Posts
Originally Posted by 2old View Post
Theoretically, the watt rating of a motor is the amount of power that it can withstand and run indefinitely. Of course, many motors can take much more power for short periods of time and many are grossly underrated. I have a 48V, 1000w system with a 30 amp controller and 52V battery (58.8V hot off the charger). I've never noticed it even getting warm.
yeah, and any motor will overheat if bogged down - like putting full power through it going up hill at slow speed. So the motor should be rated somewhere where that is less likely to happen. Many motors can be bumped up by 30% power if you don't bog them down - much more than that and something is going to overheat sooner or later...

If you want to know the exact point, you can always go to Motor Simulator - Tools
chas58 is offline  
Old 03-22-17, 05:20 PM
  #11  
2old
Senior Member
 
Join Date: Jul 2014
Location: socal
Posts: 2,318
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 393 Post(s)
Liked 165 Times in 120 Posts
Good point about bogging down C58; the rule of thumb that I use is don't go slower than 50% of your maximum speed, but I'm conservative.
2old is offline  
Old 03-22-17, 06:47 PM
  #12  
chas58
Senior Member
 
chas58's Avatar
 
Join Date: Jul 2010
Location: Michigan
Posts: 4,337

Bikes: too many of all kinds

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 976 Post(s)
Liked 223 Times in 179 Posts
Originally Posted by 2old View Post
Good point about bogging down C58; the rule of thumb that I use is don't go slower than 50% of your maximum speed, but I'm conservative.
good rule of thumb for hub motors!
chas58 is offline  
Old 03-22-17, 06:51 PM
  #13  
chas58
Senior Member
 
chas58's Avatar
 
Join Date: Jul 2010
Location: Michigan
Posts: 4,337

Bikes: too many of all kinds

Mentioned: 35 Post(s)
Tagged: 0 Thread(s)
Quoted: 976 Post(s)
Liked 223 Times in 179 Posts
Originally Posted by Robert C View Post
ceteris paribus,
I can't remember when I last heard someone use that phrase. Well done!
chas58 is offline  
Old 05-07-17, 03:13 PM
  #14  
BBassett
Senior Member
 
BBassett's Avatar
 
Join Date: Oct 2015
Location: Puyallup, WA
Posts: 428

Bikes: Tout Terrain, Panamericana

Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 194 Post(s)
Likes: 0
Liked 14 Times in 7 Posts
Remember that you can't compare hub motors and center drive motors easily. They simply can't do the same things. Yes, they are both electric motors and comply with Watts Law, but the way the power and torque are applied are vastly different. Hub motors (in my opinion) are for racing around the streets on day rides. Center drive motors will take you anywhere including Up. Most importantly, you can't suspend a hub motor.
Attached Images
File Type: jpg
DSC00327.jpg (89.2 KB, 47 views)

Last edited by BBassett; 05-14-17 at 08:24 PM.
BBassett is offline  
Old 05-07-17, 07:53 PM
  #15  
Dunbar
Senior Member
 
Dunbar's Avatar
 
Join Date: Apr 2010
Location: SoCal
Posts: 3,079

Bikes: Roubaix SL4 Expert , Cervelo S2

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 85 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Nominal motor rating also doesn't tell you peak system power. What you want to look for is the peak power output of the bike or, as mentioned, the maximum continuous current output of the controller. My Cross Current has a 350W motor but can do 700W continuous with a fully charged battery.
Dunbar is offline  
Old 05-11-17, 02:30 PM
  #16  
speculant
Junior Member
 
Join Date: May 2017
Posts: 12
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by Robert C View Post
Here it is, loaded for touring:
Does that have a solar panel or is that just a sun cover?
speculant is offline  
Old 05-12-17, 05:08 AM
  #17  
Robert C
Senior Member
 
Robert C's Avatar
 
Join Date: Sep 2006
Location: Kansas
Posts: 2,163

Bikes: This list got too long: several ‘bents, an urban utility e-bike, and a dahon D7 that my daughter has absconded with.

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 324 Post(s)
Liked 15 Times in 14 Posts
Originally Posted by speculant View Post
Does that have a solar panel or is that just a sun cover?
Solar panels, I have never plugged it in after putting them on.
Robert C is offline  
Old 05-15-17, 12:34 AM
  #18  
M2faux
Senior Member
Thread Starter
 
Join Date: Mar 2017
Posts: 56
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I like this video.
M2faux is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
rick kimura
Electric Bikes
15
05-10-17 10:05 AM
NoPhart
Electric Bikes
4
11-19-16 07:42 AM
The Big Wheel
Electric Bikes
1
10-19-16 06:43 PM
Pedidelic
Electric Bikes
2
02-02-12 12:21 PM
cvenstrom
Electric Bikes
3
03-08-10 02:10 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.