eBike kit controller technical questions

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rrrccc01   1 µW

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eBike kit controller technical questions

Post by rrrccc01 » Oct 25 2018 5:05pm

Greetings,
Newbee here, apologies for ignorance in advance! Warning this is verbose!

I bought an eBike on Amazon, enjoyed it a lot, started making mods to make it better/more to my liking, then decided rather than mod it I should build my own. So…

I bought a bike for $40 at a garage/boot sale, a Trek 820, and a kit on Amazon. Here’s a link to the kit I bought

https://www.amazon.com/gp/product/B079T ... UTF8&psc=1

I should say that I am reasonably technically competent; I have worked over 30 years in IT and have even written assembler code; I know what a bit, byte and complier is/are. However, my expertise is not in electrical or control systems, but I can find my way around bits and bytes. So…

The kit comes with a rear wheel motor, a “SW900” LCD, a brushless controller, brake levers, PAS sensor and various other whatnots. I ran into some bumps along the way, now have it put it all together and set up.

Now comes a challenge; during my test rides I’ve decided that PAS-1 goes too fast, say 14 MPH on flat terrain, and I am looking for a way to reduce the speed of PAS-1, say 8 MPH. I figure there is some setting in the controller that says how much power the controller sends to the motor for a particular PAS setting to control the speed.

Then I start to do research and determine:

1. The LCD (SW900) is primarily an interface to the controller, that is, the LCD displays status and accepts input which it sends to the controller, e.g. MPH or KPH, wheels diameter, etc. Also, there is more than one LCD available, the most common being the KT LCD 3/5 LCD the SW900.
2. The controller governs/controls how much power is sent to the motor. Again, there is more than one controller available.
3. Motors either have brushes or not, that is brushless, and the controller must match this Brush/Brushless
4. “I think” LCDs and controllers have to be compatible with each other, i.e., a KT-LCD5 and SW900 LCD will not work with the same controller

Then I find this forum/site and discover others have been down this road before me. There appears to be an application to change the controller settings but it appears to be for “KT” compatible controllers and I think my controller is a SW900 compatible controller. There’s probably a more accurate name for the controller type but I haven’t figured that out.

So finally, here are my questions…

1. Is what I want to do possible? Just change the PAS-1 setting to less power/slower speed.
2. What kind of controller do I have? Is there a “name” for it? Is it just called a SW900 compatible controller?
3. Can someone point me to the application software used to change this setting?

Thanks in advance

RC

AHicks   1 kW

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Re: eBike kit controller technical questions

Post by AHicks » Oct 25 2018 7:51pm

I learned the SW900 lesson the hard way as well. I already had experience with the LCD3 display, and thought they were compatible. As we've both learned, that's not the case. I don't know anyway of doing what you want to do. The way I went about it was to purchase a new KT based controller and LCD display. The rest of what you have should plug right in to the new controller. At worst, you may have to change connectors so they match (using bullet or spade connectors).

You can do that pretty reasonably here:
http://www.pswpower.com/ven.php?cargo.2016-3f-28ym

There's a menu of available options on the right, with a very inexpensively/attractively priced LCD3 display available. I've used these folks a couple of times now, and they've treated me right so far.

The LCD3 display will allow you into the advanced P and C parameters to configure the controller your way. That's been my experience anyway. PAS 1 should slow right down for you. You can even set max output wattage at a percentage of what you have available to really keep a handle on things....

Due to crappy "chinglish" translation of the intructions, it does take some fiddling around though. If you have too much trouble, post here. Myself, or somebody, have likely been there and know how to handle it. -Al

docw009   100 kW

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Re: eBike kit controller technical questions

Post by docw009 » Oct 26 2018 11:06am

rrccc01, your link don't work. Did you get a direct drive or geared motor? I have a 500W geared motor kit with SW900 and 22A controller from ebikeling. Can't ride it slow. Cadence sensor is like on/off switch.

I also switched to 20A KT torque simulation controller and LCD3 display. With torque simulation, the PAS sensor is still like a switch, but motor power is lowered, and it feels fairly natural.

2WheelsMovesTheSoul   100 W

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Re: eBike kit controller technical questions

Post by 2WheelsMovesTheSoul » Oct 26 2018 12:19pm

rrrccc01 wrote:
Oct 25 2018 5:05pm
So finally, here are my questions…

1. Is what I want to do possible? Just change the PAS-1 setting to less power/slower speed. Yes, sort of.... access the Parameter settings, go to P12 (PAS Strength), change to 1, exit the settings menu, then try riding it again with PAS on 1, see if the speed and accel is low enough. There's a 0-5 option on this.

2. What kind of controller do I have? I don't think so, it kinda generic, maybe try googling "EBIKELING", they use these 'SW' display units on all their branded controllers.

3. Can someone point me to the application software used to change this setting? Yes'sir! https://www.boatstogo.com/images/Saturn ... -SW900.pdf

Thanks in advance :bigthumb: no worries, hope this helps

(edit: noticed this is your first post, WELCOME to :es: )
~2Wheels

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rrrccc01   1 µW

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Re: eBike kit controller technical questions

Post by rrrccc01 » Oct 26 2018 5:51pm

Tanx for the input/replies

docw009, As I said I'm a newbie so I'm not sure why the link didn't work. It's the "standard" VoilaMart 48v 1000W rear wheel kit with the SW900 LCD and controller, basically everything but the battery. I attached the listing to this post as a PDF. I'm pretty sure it's direct drive with a 7 speed cassette.

2WheelsMovesTheSoul I'm familiar with the available settings but thanks for your post. i already have the "manual" but it's not helping. I've tried P12 1-5 but as i understand it that is the "initial", when you start peddling, PAS strength.

Also, I found another thread where someone says they swapped the SW900 with a KT LCD 3 and it worked. I messaged him to confirm, will let you know if/when i hear back.

Tanx again
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cthetoy   100 µW

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Re: eBike kit controller technical questions

Post by cthetoy » Oct 28 2018 8:52pm

I have the same setup. Sometime I set cruise control to 10mph and manually pedal from there. I upgraded my to a 72v controller with the sw900 and pas was worse. pas 1 is now 25mph which is way too fast. I’m considering swapping out the sw900 for a Cycle Analyst 3. Looks like lcd wiring is the same. The Analyst 3 can control the voltage of your Pas and not full throttle like the sw900 plus many other features

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dogman dan   100 GW

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Re: eBike kit controller technical questions

Post by dogman dan » Oct 29 2018 7:51am

Im stupid, but your problem is why I hate dumb pas. There are pas setups that are more tunable, but yours is not it appears.

My advice is learn to use a throttle. its a pain at first, but believe me, no computer is as fast and responsive to your needs as your brain. After you learn to stop putting a death grip on the throttle, you will find that long rides with just throttle don't fatigue your hand that much. Preferred throttle is a half grip.

Use the throttle like this. pick a speed. pick the gear to pedal that speed. Use the throttle to make pedaling that speed easy, but not too easy. judge by pedal pressure. This will get you a long ride that is better than any PAS. PAS will never continuously vary the power of the motor, unless its controlled by a bottom bracket pedal pressure sensor. yours just counts rotations.

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