Simple, "Dumb" Controller for Hub Motor

[Kittenrainbow]

Hey Guys

This isn't my first post here but I finally want to start building my first EV-Project.
I want to start by converting my normal city bike to a pedelec (20 km/h throttle only, 25km/h with pedal assist are allowed in my country).

I have to say that I do a lot of electrical engineering as a hobby, so I am quite experienced in the field.
Because of that, I'd like to build the controller by myself (To have the possibilities to add some more features). What I am not experienced with is the high-voltage, high-amperage stuff, so everything a normal ebike controller does.

I looked at the following components for my build:

Bafang CST 250W Motor. (I found the shop elifebike.com, which sells this motor for a competitive price. Can you recommend this shop?)
Zippy 36V 5000mAh Batterie from Hobbyking (http://www.hobbyking.com/hobbyking/store/__21377__ZIPPY_Compact_5000mAh_10S_25C_Lipo_Pack.html).

I want to use this battery because it would help me to keep the costs of the project low, as I do not want to spend "too much".
With this capacity I would expect a range of around 40Km, which should be enough. (And if not I could swap batteries on the road, or put 2 pieces in series).


My first plan was to use a normal RC ESC from Hobbyking as well (they have some really big buddies), but some research here on hobbyking showed pretty fast, that I shouldn't use one, because it lacks the current limiting feature and is built specifically for higher-rpm, lower load motors and applications (is this correct so far?).

So the question is: Are you aware of a "dump" controller? I am looking for a controller where I can connect the battery to it and the motor which offers a power outlet (for my custom controller) and a PWM input, which would enable me to controll the controller? The controllers only tasks should be to deliver as much power as I want to the motor, and I want to control the controller via pwm.

I am aware that there are some other solutions like the cycle analyst and so, which could help me as well.
But I really want to build it by myself, because I want to be able to customize it for 100% and adapt it to my needs.

Regards
Kittenrainbow

 

[motomech]

Wow, where to start?

I found the shop elifebike.com, which sells this motor for a competitive price. Can you recommend this shop?)

I use both Elifebike and BMS Battery and they are both good.

I looked at the following components for my build:
Bafang CST 250W Motor... (20 km/h throttle only, 25km/h with pedal assist are allowed in my country).

The Bafang CST is the BPM motor and is a large geared motor that can accept well over 1000 Watts. It is much too large to use to achive your goals.
The CST type motor you want is:
250W M140-R CST
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-46-K3QJ.1WASD
But it is more commonly called the:
Q100C of the "Cute" series motors:
https://bmsbattery.com/ebike-kit/651-q100c-cst-36v350w-32-hole-rear-driving-hub-motor-ebike-kit.html

...Zippy 36V 5000mAh Batterie from Hobbyking (http://www.hobbyking.com/hobbyking/store/__21377__ZIPPY_Compact_5000mAh_10S_25C_Lipo_Pack.html).

I want to use this battery because it would help me to keep the costs of the project low, as I do not want to spend "too much".
With this capacity I would expect a range of around 40Km ...

Even with smaller motor and low power controller, the most you can expect to see with 5Ah of Lipo is 30Km. And that is with strong pedaling.

(And if not I could swap batteries on the road, or put 2 pieces in series).

I will assume you got confused when translating language in your head because someone who has "electrical engineering as a hobby" would know that 10s in series with 10S would be 78 Volts, a little to much for this system

Elifebike offers two controllers in 3 versions each(lcd meter, led meter and no meter) that can serve your needs. They are:
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-5G-GN6T.6Y9YQ
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2014-3K-SAUG.5TSEX
They are simple and durable, but the 36V version has a lvc of 31V, too low for 10S. I use 9S for that reason.
For 38V battery and low power, the 6 FET would be enough.

Having said that, your plan to build a controller to control a controller makes no sense at all.
BMS Battery offers the SO6S sine-wave with the SLCD-3 display that is very advanced and together, they offer every feature that one could possibly use at a very low cost.
https://bmsbattery.com/ebike-kit/546-s06s-250w-torque-simulation-sine-wave-controller-ebike-kit.html
https://bmsbattery.com/ebike-kit/737-72v-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html
Matched with the Cute motors, this a fantastic system which makes almost no sound at all.

IMO, it would be better to save your engineering skills for a something more advanced than a simple, low cost, single hub motor system.


Too bad you are in Germany, I have everything you need, used.

 

[Kittenrainbow]

Hi Motomech and thank you for your reply

Well, looking at those prices I have to say that I'd be really stupid to build it all myself
Just some questions left which I couldn't answer myself:

-As I said earlier, I want to use the bike in 2 modes: the lazy mode (throttle control, no pedalling) and the normal PAS mode.
On the LCD you recommended (S-LCD3) I can set a maximum speed (25km/h default). Is this for both modes or is there a way to set 20km/h for the throttle and 25km/h for PAS?
Looking at the motor I ask myself if it is worth to worry about it anyways: What could be a probable max speed (based on a 26" wheel)?

-Am I right that, if I add the normal pedalling sensor, I do not really need to add brake-contacts (and recupperation isn't possible with this motor anyways)? This would be favorable, because I have hydraulic disc brakes on my bike and can't swap the brake-levers.

This is my cart ATM, did I left anything out?

S06S 250W Torque Simulation Sine Wave Controller
72V S-LCD3 LCD Meter for S-Series Controlers
36V10Ah Right Off Bottle Battery Pack with Charger
Thumb Level Throttle
PAS--Pulse Padel Assistant Sensor With 12 PCS Magnets
King Meter Speed Sensor

Regards
Kittenrainbow

 

[d8veh]

The speed limit setting is global, so it affects both the throttle and pedal assist the same.

There is another option. The S06S uses current control by default, where the different level settings relare to how much current is given, but you can change the mode of operation to speed control, where each level relates to a maximum speed, so you get five different speed settings. Level 5 will be the same as the global maximum speed.

Some of the Q-series motors have an internal speed sensor, so you might not need to connect the wheel-speed one. You should still order it in case your motor doesn't have one. You might want to fhange the motor in the future.

 

[Kittenrainbow]

Hi d8veh and thank you for your reply

Okay, it insn't really a problem if the setting is global, I just wanted to know
Any further thoghts regarding my cart @BMSBattery? Thank you for the comment regarding the speed sensor though.

Regards
Kittenrainbow

 

[motomech]

Hi Motomech and thank you for your reply

Well, looking at those prices I have to say that I'd be really stupid to build it all myself
Just some questions left which I couldn't answer myself:

-As I said earlier, I want to use the bike in 2 modes: the lazy mode (throttle control, no pedalling) and the normal PAS mode.
On the LCD you recommended (S-LCD3) I can set a maximum speed (25km/h default). Is this for both modes or is there a way to set 20km/h for the throttle and 25km/h for PAS?
Looking at the motor I ask myself if it is worth to worry about it anyways: What could be a probable max speed (based on a 26" wheel)?

-Am I right that, if I add the normal pedalling sensor, I do not really need to add brake-contacts (and recupperation isn't possible with this motor anyways)? This would be favorable, because I have hydraulic disc brakes on my bike and can't swap the brake-levers.

This is my cart ATM, did I left anything out?

S06S 250W Torque Simulation Sine Wave Controller
72V S-LCD3 LCD Meter for S-Series Controlers
36V10Ah Right Off Bottle Battery Pack with Charger
Thumb Level Throttle
PAS--Pulse Padel Assistant Sensor With 12 PCS Magnets
King Meter Speed Sensor

Regards
Kittenrainbow

What could be a probable max speed (based on a 26" wheel)?

With 201 wind motor, 26" wheel, and 36V battery=27 Kph.
Q100H 260 Wind motor=31 Kph
"H" motor is option for frt. whl. mount.
Frt. whl. mount works very well with low power system(See my second link).
CST w/ 9-speed cassette requires extreem "dishing" to center whl. Not that difficult, but can be time consuming, as more dish, more likely to go out of true.
For hills, "H" 201 motor is best. For flat without speed restriction, "H" 260 is best(260 not option for CST).
For flat while maintaining scrict speed limit, 201 CST is fine.

Your cart-
PAS installation depends on crank type, I suggest you order both types of 12 magnet disc.s.
You want other brand speed sensor.
Order spoke wrench.

Need for Ebrake?-
Many PAS systems have "overrun"(continue for 2 to 3 seconds after pedal stop), Ebrake absolutely necessary.
But not sure about PAS w/ SO6S, as I never used them together
I use cruise control without ebrake and "flip" the thumb throttle quickly to de-activate, safe enough with low power systems.
If you need ebrake with Hyd. brakes, you will need to fab. reed switch into original brake handles.
D8veh has posts on this mod.
Whichever motor you use, you will have cables too long.
Some shorten, I use 4mm bullet conectors on power wire, 3.5 mm bullets on phase wires and JXT on Hall connector.
Some roll extra wire and put into a small bag.
I use a combo of both.
A good idea is to replace the kit's crimp-on phase bullets, these are the "weak link" and can start to melt on steep hills.

 

[fellow]

S06S controller exist in 48V version too, here http://www.aliexpress.com/store/product/Regeneration-Electric-Bicycle-Brush-less-Controller-48V-6-MOSFET/914437_1749495210.html.
http://www.groetech.de used to sell it in 48V version too, but I can't found right now.

Q100h 36V 201rpm is well proven combination with S06S at 48V nominal (54.6 fully charged). Top speed is about 32km/h in 26" wheel in that case. You can set speed limit to 25 Km/h in "hidden" display setting. You can even limit the speed with a simple throttle resistor (trial or error/pot first) if you dislike display use. Higher voltage gives you better acceleration past the half top speed, and better climbing ability (less speed sag at hills at higher speed), so it's wiser to limit it than use 100% of possible speed (don't forget the back EMF, fight it with higher voltage). Increased voltage and current gives you better torque at all rpms. Keep the original 14A value, or increase to max 17A. Q100H saturates at 20A and beyond, allow for some margin. You can even use 40ml ATF oil thru the disc screw, to keep the Q100H internals happy.

Battery is easy to DIY from the Panasonic NCR18650pf cells. 1 cell is 2,9Ah, 4,2V, 10A cont, 18A for 5 seconds pulse. 13s2p gives you about 18Km, 13s3p gives you about 30Km+ without pedalling. Cost:about 6.45€ per cell with U-tabs. No bms is needed for those cells, LVC is already set in S06s to about 40V and they are very well balanced chemistry (safer than other deathcells too). You can buy them in Germany, here https://www.akkuteile.de/lithium-ionen-akkus/18650/panasonic/panasonic-ncr18650pf-a-2900mah-3-7v-ncr18650pd-loetfahne-u/a-1006341/

 

[999zip999]

Ok you want a hobby ? Make a good battery. Get the samsung or Panasonic cells from Poland in the New for sale section. Add a bms and the right charger.
Can you make a spot welder.

 

[Kittenrainbow]

Hey Guys

Thank you for the many replies. I am starting from the top.

I think I am going to take the 201 Q100C Rear Driving Motor, as the allowed speed limit here is 25 km/h anyways and it would offer better climbing ability
Thank you for your recommendations, regarding the cart. I will follow them.
I allready have a spoke wrench

First I am going to try without a brake sensor. I can add one later anyway.

SO I think I am ready to order.
Thank you guys

 

[motomech]

Kit wheels use 13 Ga. spokes, not common bicycle size of 14 Ga.

 

[d8veh]

That's right. Most spoke keys don't fit, but the $1 ones from BMSB do fit.

 

[fellow]

First I am going to try without a brake sensor. I can add one later anyway.

You can buy throttle with green push button and connect it to act as an emergency brake. This in case throttle get stuck on 100% due to malfunction or rain.