Search found 7654 matches

by Alan B
Mar 07 2020 11:00pm
Forum: E-Bike Technical
Topic: 60 volt vs 72 volt
Replies: 84
Views: 7693

Re: 60 volt vs 72 volt

Powervelocity Controllers use Sinusoidal Commutation, not FOC (Field Oriented Control). The Sabvoton that I have is FOC as are the PhaseRunners. There's a world of difference in the way they generate sinewaves and in the feature sets they offer. https://www.motioncontroltips.com/faq-whats-the-differ...
by Alan B
Mar 07 2020 10:45pm
Forum: Motor Technology
Topic: maxing out phase amps
Replies: 22
Views: 2517

Re: maxing out phase amps

Justin has measured saturation on a number of motors, there's an old thread on the subject. http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=14494 It's hard to saturate a motor instantly due to the inductance of the winding, unless you have infinite voltage to drive it with. Justin found it ...
by Alan B
Mar 07 2020 9:56pm
Forum: General Discussion
Topic: World Domination, I just got my self a 3d Printer!!!
Replies: 642
Views: 74812

Topeak Trunk Risers

Sometimes we want to use a Topeak trunk with some regular saddlebags. The trunk has some small fold-out saddlebags but they aren't very large or heavy duty. Unfortunately the trunk sits too low and the saddlebags need more room to clip to the bars. So I whipped up a variation of my earlier design to...
by Alan B
Nov 15 2019 10:45am
Forum: E-Bike Non-hub Motor Drives
Topic: Diamondback OverDrive 27.5 "RidgeRunner"
Replies: 69
Views: 14812

Re: Diamondback OverDrive 27.5 "RidgeRunner"

I saw the announcement about the bridge. Very interesting.

I recall reading about Eric of Lunacycle riding across the Golden Gate bridge at night during a big storm. Quite the adventure.
by Alan B
Oct 29 2019 7:18pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

Working with closed systems is so frustrating. Hence one reason most folks on ES use DIY or modified setups. I think undercharging the battery to make it last longer is silly. Use it. After several years of use replace it. Hobbling an already marginal system is not worthwhile, in my opinion. The onl...
by Alan B
Oct 29 2019 7:06pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

OK no time now, will parse later see if specific answers are there to see if my understanding is better. You have to model your actual data to get specific useful predictions. Generalizations don't get you there, even if they are all correct for some situations. Well when choosing and sourcing the ...
by Alan B
Oct 29 2019 5:00pm
Forum: Battery Technology
Topic: Understanding and Using EGO Power+ Batteries
Replies: 89
Views: 26639

Re: Understanding and Using EGO Power+ Batteries

PETG is a good choice. I haven't tried TPU yet, have heard it can really bond to the PEI and create problems. PETG bonds pretty well to PEI as well, damaged one build plate that way.
by Alan B
Oct 29 2019 4:39pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

You have to model your actual data to get specific useful predictions. Generalizations don't get you there, even if they are all correct for some situations. You need enough voltage to: 1) overcome back EMF for the speed you are going and have enough voltage left to both: 2) overcome resistive losse...
by Alan B
Oct 29 2019 9:41am
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

It's not like I want to climb that hill at 25km/hr. So, if back EMF limitting the current isn't the issue reducing torque, there has to be something else on my bike reducing the current at lower battery voltage. If I read all comments correctly, there is no electrical limitation that explains such ...
by Alan B
Oct 29 2019 2:09am
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

At very low speeds battery voltage is not much of a problem because back EMF is very low so full torque can be generated. As speed rises the ability to generate the same torque falls off due to back EMF.

What they told you isn't wrong, it is just part of the whole picture.
by Alan B
Oct 29 2019 2:06am
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

This thread started with an observation about reduced torque due to battery sag. Clearly that is an example of this. There are many ways to think about these electromechanical systems. Some of them lend themselves to understanding more than others. The back EMF of the motor fights the battery voltag...
by Alan B
Oct 28 2019 11:04pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

Lots of good info here, but the motors are the same (as was mentioned). So referring to one as a 36V motor and the other as a 72V motor is confusing. Might be better to edit it and call it the 36V system vs the 72V system. And you can get more performance out of the same motor with a 72V system... T...
by Alan B
Oct 28 2019 7:50pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

The simplest solution is to avoid using the end of the battery capacity where sag becomes a factor. Increase the capacity of the battery by paralleling additional cells. They can be tied in so the BMS, charging, etc remains the same.
by Alan B
Oct 28 2019 7:33pm
Forum: E-Bike Technical
Topic: 60 volt vs 72 volt
Replies: 84
Views: 7693

Re: 60 volt vs 72 volt

I checked, he plans to use them so that didn't help. I may have some other 6S that I should dispose of, not sure. They may not be a good fit for you, 25V full charge works for 25/50/75/100V but skips over some other desirable voltages. I also have a 14S balancing charger that I haven't used in awhil...
by Alan B
Oct 28 2019 4:37pm
Forum: E-Bike Technical
Topic: 60 volt vs 72 volt
Replies: 84
Views: 7693

Re: 60 volt vs 72 volt

Great.

I gave some lipos to a friend, he isn't using them, perhaps I should see if he still wants them. Mostly 6S5AH Turnigy. What are you looking at using?
by Alan B
Oct 28 2019 4:34pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

I see 2 possible options to always get the maximam possible torque. 1. Use a boost converter so that the motor always get's 40V. This has the disadvantage that the current drawn from the battery will increase. If we consider The 40V * 8A example, that's 320W Assume the converter efficency is 90%, t...
by Alan B
Oct 28 2019 4:26pm
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

Voltage sag means higher amps required just to get the same power. Keep the voltage higher, get your power at lower amps, less stress, more efficient less waste as heat Raising battery voltage lowers battery current for the same power. However motor voltage/current don't change for same power. Cont...
by Alan B
Oct 28 2019 11:47am
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

Voltage sag means higher amps required just to get the same power. Keep the voltage higher, get your power at lower amps, less stress, more efficient less waste as heat Raising battery voltage lowers battery current for the same power. However motor voltage/current don't change for same power. Cont...
by Alan B
Oct 28 2019 8:10am
Forum: E-Bike General Discussion
Topic: Does torque normally change with battery voltage?
Replies: 30
Views: 2205

Re: Does torque normally change with battery voltage?

Welcome to ES. Yes torque often changes with battery voltage, not directly but due to consequences. It is Normal. Torque is (directly proportional to) motor current. Max motor current is from (battery voltage minus back EMF) divided by system resistance. Back EMF is proportional to speed (and motor ...
by Alan B
Oct 25 2019 11:16am
Forum: E-Bike General Discussion
Topic: RadPowerBike RadCity Commuter
Replies: 152
Views: 7138

Re: RadPowerBike RadCity Commuter

RadCity.jpg A great looking commuting machine. Clearly some people want to argue rather than add real value to this thread or to ES. There is no requirement that we prove anything. This is not a debate. The experience of maintenance and reliability of different drive system types are well covered e...
by Alan B
Oct 25 2019 2:34am
Forum: E-Bike General Discussion
Topic: RadPowerBike RadCity Commuter
Replies: 152
Views: 7138

Re: RadPowerBike RadCity Commuter

I just tested the throttle onset and it does have a little more deadband than some, but not all that much. We could adjust the position of the paddle on the half-twist and change the feel that way to some degree. A more programmable controller would really open things up for adjustment. Traditional ...
by Alan B
Oct 24 2019 11:45am
Forum: E-Bike General Discussion
Topic: RadPowerBike RadCity Commuter
Replies: 152
Views: 7138

Re: RadPowerBike RadCity Commuter

It should have a significant dead travel, that's standard. I believe the point is that your motor springs into action only when you really want it to, not because you accidentally moved the throttle a little when you were wrestling the handlebars etc. Perhaps, however I've not seen a super-wide low...
by Alan B
Oct 23 2019 11:40pm
Forum: E-Bike General Discussion
Topic: RadPowerBike RadCity Commuter
Replies: 152
Views: 7138

Re: RadPowerBike RadCity Commuter

I recall a thread years ago where a guy wanted to climb hills faster. He bought an Optibike for 15K or so and knew he had the best there was. Then he went on a ride with some other folks and was totally blown away by a DIY direct drive hubmotor bike that didn't even have a pedal chain. Putting some ...
by Alan B
Oct 22 2019 1:58pm
Forum: E-Bike Non-hub Motor Drives
Topic: Diamondback OverDrive 27.5 "RidgeRunner"
Replies: 69
Views: 14812

Re: Diamondback OverDrive 27.5 "RidgeRunner"

The clear is nice. I wonder why they dropped it. The black seemed better than the stainless steel for my Diamondback. Each build is different.
by Alan B
Oct 22 2019 9:17am
Forum: E-Bike Non-hub Motor Drives
Topic: Diamondback OverDrive 27.5 "RidgeRunner"
Replies: 69
Views: 14812

Re: Diamondback OverDrive 27.5 "RidgeRunner"

The one I bought is black, stainless was also available. My older ones are dark tinted clear.