Please recommend me a controller to match

fatboy72

1 mW
Joined
Dec 31, 2021
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14
As I didn't get a reply from the facebook group therefore I will try here.

I have a new 48v 750w 20ins geared motorhub (rear fat rim) and need a controller to go with.

I don't need throttle just PAS, no need display too. I thought of getting the KT-25A with LCD4
but I don't want a display.
 
how about a picture of the motor or a link to where you had purchased it. most of us have learned that we need do you have connectors crimpers and a soldering iron. it would be nice for a first person to get a controller with a self-learning wire
what exact battery you have because a battery a motor and a controller must all match.
 
fatboy72 said:
As I didn't get a reply from the facebook group therefore I will try here.
What facebook group?

I have a new 48v 750w 20ins geared motorhub (rear fat rim) and need a controller to go with.

I don't need throttle just PAS, no need display too. I thought of getting the KT-25A with LCD4 but I don't want a display.

You can use KT controllers without a display, but it will likely only operate in a default mode (which might not be the assist level you want it in, since that is chosen using the buttons on the display or separate button pad), when you short together the keyswitch / ignition wires in the connector that the display would plug into. (without a switch it's going to always be on as long as the battery is connected).

Or you can put the display (except for the buttons, if they are on a separately mounted piece) inside your battery case or display, after you have setup the bike to work like you want. Then just have the buttons on your handlebars, so you can change the assist level as needed, and turn the bike on and off.

Which kind of PAS do you want? There are at least three.

The most common PAS simply gives you the full power of whatever level of assist you choose on the display buttons. Without a display on this type, you can't change that level, and are stuck with whatever it's default is. You don't have any control over the speed of hte bike except by pedalling a little then stopping pedalling, (and maybe braking), and repeating that. Continuous pedalling regardless of how fast or hard you pedal just gives whatever speed or power level the assist was set to.

The next type is cadence-controlled PAS, so that the faster you pedal the more assist you get, so you go faster with faster pedalling, and slower with slower pedalling. This is what I have on my SB Cruiser trike using the Cycle Analyst v3 to make "generic" non-PAS controllers work via PAS.

The third type is torque-controlled, so that the harder you pedal the more assist you get; some of these also are controlled by speed of pedalling.



What voltage battery do you have? This is important because the controller must be able to handle that much voltage, and it must have an HVC and LVC that works with your battery's voltage range.

And what is the battery's Amp (A) rating? (also it's Amp-hour (Ah) rating, which is a completely different thing) This is important because your battery must be able to supply all the power for the system, so you don't want to get a controller that stresses it out by pulling too much current from it.
 
Battery is 48v 23aH, Bafang 48v 750w geared motorhub. Common PAS sensor.

Mostly flat road, occasionally slopes not steep slopes.

I am told that with just PAS, I will not be able to get full power of the controller without throttle.

I am good with soldering, etc therefore installation is not a problem.
 
fatboy72 said:
Battery is 48v 23aH
While it is very likely that at 23Ah it is capable of supplying the 750w your motor is designed for, knowing it's actual A (amp) rating might be useful for you at some point, if it is marked on it or is on the site you bought the battery from. (Note that the A rating is not the Ah (amp hour) rating; they look similar but are completely different things).

For a 48v battery, you do want to be sure to get a controller that is either made for 48v (13s battery, vs a 52v, 14s battery, or higher, or a 36v or lower battery) so that the controller's LVC won't either shut off too soon, or not shut off soon enough, to help keep the battery healthy.

Some controllers that don't state their LVC (may call it "protection level" or similar) basically don't have an LVC or have it set so low that it "works on anything", and that means your battery can be worked too hard by emptying it too far each time. Some have an LVC you can set in the display (or using a USB cable on your computer); if they do you need to be sure to set it before riding so it protects the battery but doesn't cause you early shutdowns. ;)


I am told that with just PAS, I will not be able to get full power of the controller without throttle.
As I noted, that depends on the kind of controller's PAS you want to use (it's not just the sensor you have--it's how the controller responds to it). And it isn't just whether or not you get full power, its' whether you have actual control of the speed with just PAS; depends on the controller design.

How do you want the bike to operate for you?

Do you want it to just go one speed?

Or do you want control of the speed?

If you just use the basic PAS common to many controllers, you can't simply control the bike's speed with the pedals without the display/buttons to change assist levels / speeds.

You need a controller with cadence-control of the speed to directly control the bike speed using the pedals, without the display/buttons. (or use a torque-sensor type)


If you dont' know the answers to any of these, the best option is to get the system that has a display with a separately-mounted button unit, so you can hide the display but still have access to the buttons. That way you can change the behavior of the system to suit you best, within whatever range of options it has.

Otherwise you're probably going to be stuck trying different PAS-capable controllers that don't use displays until you find one that works the way you want it to out of the box.
 
@amberwolf, I understand what you mean about the battery and the low cutoff voltage of the controller. I have to make sure the BMS output amperes match the max amp of the controller.

From your explanation of controlling the speed of system, I agreed best to use with a display that can control the speed and level of the PAS as it is without the throttle.

I think I might have to go with KT controller. I have the Greentime controller in consideration but like you said no control over the speed of the PAS, just one speed.

Thanks
 
fatboy72 said:
@amberwolf, I understand what you mean about the battery and the low cutoff voltage of the controller. I have to make sure the BMS output amperes match the max amp of the controller.
I expect at the capacity your battery is at, the latter won't be a problem (they usually use a BMS and cells that can do at least 1C, or 1 x the capacity, which for yours would be 23Amps. Safer to check if you can get the info, but probably ok.

(it's ok if the battery can supply more than the controller takes, but not the other way around. I.e.: a 50A battery/BMS, but a 10A controller is ok, but a 50A controller and a 10A battery isn't).

From your explanation of controlling the speed of system, I agreed best to use with a display that can control the speed and level of the PAS as it is without the throttle.

I think I might have to go with KT controller. I have the Greentime controller in consideration but like you said no control over the speed of the PAS, just one speed.
I don't know which mode the Greentime uses. If it uses true cadence speed control, you're ok. If not, then it's full power at whatever assist level the PAS is set to (either by the factory or by you if it has a user setup or control for that).


Alternately, for pedal-speed control of the system, if you don't mind the extra money and the time to set it all up, you can use any throttle-only controller (that doesnt' even have a PAS option) that suits your needs, and then put the Cycle Analyst 3.x between your cadence-PAS sensor and the controller's throttle input, and set the CA up for cadence-PAS control of the speed (or of the power or current), and you can also limit the max speed of the system via the CA if you want or need to do that for any reason. The CA itself can, like the KT display, be hidden away in a bag or battery casing, it doesn't ahve to be accessible. If you want to use the preset and/or variable-control functionality of the CA (not required) you can use remote buttons to access that.

That's what I use on my trike (though I have the display on the bars so I can keep track of a few things it monitors).
 
Ok. Well, as long as you want that and can handle it, that's ok. Otherwise I'd use the Cycle Analyst to moderate the PAS the way you want, using the throttle input of the controller instead, or use the KT (or similar) controller and hiding the screen.


BTW, if you're willing to go thru the process, there is open source firmware OSFW that you can install on some (many?) KT controllers and displays that will let you customize the way it works pretty completely, and AFAIK it even supports torque sensors and actual cadence speed control. It's in threads by Casainho, Stancecoke, et. al. Sorry I don't have the link handy.
 
amberwolf said:
The next type is cadence-controlled PAS, so that the faster you pedal the more assist you get, so you go faster with faster pedalling, and slower with slower pedalling. This is what I have on my SB Cruiser trike using the Cycle Analyst v3 to make "generic" non-PAS controllers work via PAS.

The third type is torque-controlled, so that the harder you pedal the more assist you get; some of these also are controlled by speed of pedalling.

Do you get a natural cycling feel when using cadence based PAS (as opposed to using torque controlled one) ?, During uphill & start, does the cadence based PAS assist provide a comfortable riding experience ?
 
afzal said:
amberwolf said:
The next type is cadence-controlled PAS, so that the faster you pedal the more assist you get, so you go faster with faster pedalling, and slower with slower pedalling. This is what I have on my SB Cruiser trike using the Cycle Analyst v3 to make "generic" non-PAS controllers work via PAS.

The third type is torque-controlled, so that the harder you pedal the more assist you get; some of these also are controlled by speed of pedalling.

Do you get a natural cycling feel when using cadence based PAS (as opposed to using torque controlled one) ?, During uphill & start, does the cadence based PAS assist provide a comfortable riding experience ?

Depends on what you feel is natural, since natural for a bike is no assist. There's a few ways to adjust the cadence based PAS with the CA to make it feel more natural. If you normally downshift when riding up a grade, then the CA has the ability to increase assistance when your cadence increases, so you don't have to make up all of the difference when load increases. You can adjust the ramp to what feels best for you, but it's not going to be like a torque PAS where you need to increase your own effort to get more assist, which may feel more natural, too. From a dead stop, the cadence based PAS doesn't provide any assist, where a torque based PAS does, but that's what a throttle is for.
 
E-HP said:
afzal said:
Do you get a natural cycling feel when using cadence based PAS (as opposed to using torque controlled one) ?, During uphill & start, does the cadence based PAS assist provide a comfortable riding experience ?

Depends on what you feel is natural, since natural for a bike is no assist.

By natural for ebikes, I meant a bicycle on steroids feel :wink: i.e. for example, when 1Nm torque is applied on the pedal, wheel should get 5Nm push, as torque exerted on the pedal is what the rider feels as the effort.

I would like to know from people who have rode ebike with cadence as well torque based PAS & how they compare the ride experience between these two. Probably I will start another thread instead of hijacking this one.
 
afzal said:
Do you get a natural cycling feel when using cadence based PAS (as opposed to using torque controlled one) ?, During uphill & start, does the cadence based PAS assist provide a comfortable riding experience ?
For me, personally, on startups, because my trike plus me weigh over 500lbs, the answer is no, because my knees and right ankle aren't able to do normal pedalling under loads, so a torque sensor would work better for that (I'm slowly and intermittently working on a solution to do that in my Nano Tidbits thread).

But for most people that can pedal normally, it does work well, as long as they are shifting into the correct gearing for the pedalling for the conditions they're under at that moment.

For uphills, as long as I am already moving, then yes, it works perfectly fine, because I have enough motor power to compensate for my legs' lack of that. ;)


To me, it is much more natural than a throttle, and far more controllable than the on/off full-power style of PAS control (which I've used on other bikes like my Fusin Test Bike that had a medium-large geared hub in the rear wheel), even when the assist level is selectable via buttons from the display. (having to change that level all the time while riding in traffic is distracting, unnatural, and sometimes actively dangerous for me).


A combination of torque and cadence works "best" for more situations, but is more complicated, and the Cycle Analyst doesn't use the torque sensor in the way necessary to make it most natural and easiest to use. That's what I want to change with my Nano addon if I ever get that done.

The torque and cadence sensors together with the CA work great once you get teh cranks moving, so if you're in a low enough gear at startup, then it does work like having bionic legs, basically like you describe, and you can setup the balance between human input and motor output just about any way you want.

My only problem with it is at startup from a complete stop, and only because of my knees/ankle plus the very heavy weight of my cargo trike and loads plus me.


But there are torque sensors like the Erider BB type that provide a simple throttle signal that can directly control any typical controller, even if it has no PAS input (if it does have one, then it's cadence output can connect to that if you like, but I don't know how the setup would work unless the controller is fine-tunable). Using the Erider BB with the CA, though, would let you tune it however you wanted, with the Erider as the throttle input and not the torque sensor input. (still using the Erider cadence output to the PAS cadence input). Then the CA throttle output to the controller throttle output.

I have never used the Erider BB, but it seems like a more universal solution than the Thun or TDCM that I have used so far (which don't output a standard throttle signal and have to go thru the torque sensor input on the CA).
 
afzal said:
By natural for ebikes, I meant a bicycle on steroids feel :wink: i.e. for example, when 1Nm torque is applied on the pedal, wheel should get 5Nm push, as torque exerted on the pedal is what the rider feels as the effort.

I would like to know from people who have rode ebike with cadence as well torque based PAS & how they compare the ride experience between these two. Probably I will start another thread instead of hijacking this one.

So you want to work harder when climbing a hill. You can do that with either cadence or torque based PAS, but you won't have the assist from a standing start with cadence. I don't do the math between my legs and assist, since I don't care about it, and I mainly care about how much or little effort I add to the equation.

I like my legs providing the same level of effort on flat ground up to about and 8% grade and try not to go below 15mph. I never shift from 46:13 until the grade greater than 8%, above that I downshift and cadence increases, and so does the assist, and downshift more for more assist. I have to pedal harder, or adjust the assist up (or more easily apply some throttle) when the grade is above 15% or so (or just twist the throttle and stop pedaling when I'm lazy).

I don't think there's anything "natural" once you add assist. You need to aim for what feels and works for you. I got the CA with the intention of moving to a torque based PAS if the cadence PAS wasn't good enough, but truthfully you can replicate a toque based PAS or cadence based PAS just by manipulating the throttle alone.
 
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