Hi,
This is my first post, please bear with me if I ask nonsense things (I will try my best not to). Also, English is not my mother language but I will try to explain myself as best as I can.
I have been thinking of building my own electric bike. Since I am not a bike expert I will take my time for the build.
The system I want to build is a mid-drive using a cute motor. Why? Well I want to use a small motor and still be able to use the gears of my bike with it. I would like to explore more the area where I live but here is a bit hilly and there are very steep hills (around 30° in some areas). I have a 820 trek mountain bike but with those hills it does not take too long until I lose the fun of riding it. Thats the main reason why I decided I need an electric bike with a somewhat powerful motor, yet discrete and small enough to mount it as a mid-drive.
I am not aware of the disadvantages building a mid drive this way might have but I’m happy to hear your opinion about it
For this mid-drive I want a system that is silent, reliable, upgradeable up to some extent, not too expensive, powerful enough and easy/ not-too-expensive to repair in case something breaks down.
Some considerations:
-- I am more interested in torque than in speed.
-- My optimal pedal cadence is approx. 85 rpm.
-- I weight ~138 lb or ~63 kg.
-- Ideally I want to try to order from one distributor to save as much as possible in shipping and taxes. Here in Germany things get expensive really fast.
-- Unfortunately I don’t really have $1000 or so to spend in a MAC system, although I would love to… someday…
Question:
How do you calculate the real load speed of the motor? I plan to use a 1:2 reduction ratio hoping to have a similar cadence to mine. Would that ratio be good enough?
Features I need:
-- The motor needs to be powerful enough to assist me with hill that are ca. 30° while I also pedal. Also it needs to be able to pull uphill a trailer with 20-40kg.
-- The bike need to be able to go through very uneven off-roads with steep slopes.
-- Freewheeling
-- Quietness. I hate whinny motors (I think I don’t mind a deep motor growl as long it is not very loud)
-- Smoothness. It should work with smooth transitions between PAS levels, etc.
-- The motor should be powerful enough to be mounted in the rear wheel if need and still be able to provide considerably hill assist (although not for 30° hills anymore)
-- The motor needs to be compact enough to mount it as mid-drive
-- Ideally I would like to be able to replace the battery myself, thats why I am considering a Headway pack. If you think there are better/ very-strong reasons to use a Panasonic pack, instead of a headway pack, feel free to share your thoughts.
The components I am considering for my build are:
-- The Cute 201 Q128H https://bmsbattery.com/ebike-kit/775-q128h-36v800w-rear-driving-ebike-hub-motor-ebike-kit.html (from BMS). I do not know if I want the cassette (500W) or the freewheel (800W) version yet. Just curious, do you think a normal Q100 will be enough for this application?
-- This S12S torque simulation sine-wave controller (from BMS) https://bmsbattery.com/ebike-kit/552-s12s-500w-torque-simulation-sine-wave-controller-ebike-kit.html?search_query=s12s&results=13
-- This 36V 10Ah (Max. 30A continuous) https://bmsbattery.com/ebike-battery/114-36v10ah-lifepo4-battery-38120-battery-pack-with-carrier-headway-battery.html Lifepo4 battery with the charger and rack included (from BMS). I also think the battery would be able to provide more than enough juice for the mid drive and the gears of the bike, since I would only activate the throttle via BeamTS sensor in the very steep hills and the rest of the time I plan to ride the bike only with the PAS levels.
-- An dditional charger for the battery (I have read that the BMS charger are not good, if you know a good charger for 36V Lifepo4 that is not as expensive as the Cycle Satiator would you mind sharing the info here?).
-- The S-LCD3 display to program the controller (from BMS). https://bmsbattery.com/ebike-kit/670-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html#/310-color-white
-- A 12 Magnet cadence sensor (from BMS). https://bmsbattery.com/ebike-parts/504-pas-pulse-padel-assistant-sensor-with-12-pcs-magnets-parts.html
-- Speed sensor (from BMS). https://bmsbattery.com/ebike-kit/661-king-meter-speed-sensor-ebike-kit.html
-- E-brakes (from BMS). https://bmsbattery.com/ebike-parts/52-brake-grip-parts.html
-- BeamTS torque sensor for the throttle signal (does anybody knows where to buy it? I have been looking for distributors but I was not able to find many options). Grin is listed as a distributor but the item has been for a long time out of stock in their website.
-- I need to build my own brackets for the motor and the BeamTS sensor.
-- A on/off switch for connection/disconnection of the BeamTS torque sensor to/from the controller.
As I understand it, the current limiting feature using the S12S controller applies only to the PAS and not to the throttle (which would give instead the maximum current of the controller, right?).
I want to connect the BeamTS to the controller whenever I need immediate assist and full power (for example starting from a stand still position when going uphill). When I do not need the immediate assist I would then drive only with the PAS assist levels. Therefore, ideally I would like to restrict the max. amps of the S12S with the display to half of its maximum (setting the C5 parameter value to a value of 03 or “maximum controller’s current” divided by 2) and use the 5 different assist levels along with this restricted current.
Question:
Which maximum current value do the 5 different PAS assist levels take as reference?
Do they follow the restricted current determined by the C5 parameter value and then divide it by 5 so that the assist is:
-- 0% of the C5 parameter current @ assist0
-- 20% of the C5 parameter current @ assist1
-- 40% of the C5 parameter current @ assist2
-- 60% of the C5 parameter current @ assist3
-- 80% of the C5 parameter current @ assist4
-- 100% of the C5 parameter current @ assist5
-- I am assuming the 5 different PAS levels increase/decrease the current in increments of 20% per assist level. Is this percentage how the amount of assist is divided?
Or do they simply divide the “maximum controller’s current” by 5 giving:
-- 0% of the maximum controller’s current @ assist0?
-- 20% of the maximum controller’s current @ assist1?
-- 40% of the maximum controller’s current @ assist2?
-- 60% of the maximum controller’s current @ assist3?
-- 80% of the maximum controller’s current @ assist4?
-- 100% of the maximum controller’s current @ assist5?
-- Is there any other way to restrict the throttle max. current using the 5 different assist levels with the current configuration?
I was also considering, as an alternative, to match the motor to the following controllers:
-- 6FET Lyen mini monster programmable controller. http://www.lyen.com/
-- 9FET Infineon programmable controller from Em3ev. http://em3ev.com/store/index.php?route=product/product&path=41_38&product_id=79
-- What are your thoughts in general about these two instead of the S12S controller when used with the Q128H or the other cute motors?
-- Would they also allow current limiting/control for both the PAS and the throttle? And would that only be possible in combination with a Cycle Analyst?
I think that is pretty much it.
Any opinions, recommendations and constructive criticism are very welcome. I hope you also enjoy the build and hope it can be helpful to others as well.
Thanks!
This is my first post, please bear with me if I ask nonsense things (I will try my best not to). Also, English is not my mother language but I will try to explain myself as best as I can.
I have been thinking of building my own electric bike. Since I am not a bike expert I will take my time for the build.
The system I want to build is a mid-drive using a cute motor. Why? Well I want to use a small motor and still be able to use the gears of my bike with it. I would like to explore more the area where I live but here is a bit hilly and there are very steep hills (around 30° in some areas). I have a 820 trek mountain bike but with those hills it does not take too long until I lose the fun of riding it. Thats the main reason why I decided I need an electric bike with a somewhat powerful motor, yet discrete and small enough to mount it as a mid-drive.
I am not aware of the disadvantages building a mid drive this way might have but I’m happy to hear your opinion about it
For this mid-drive I want a system that is silent, reliable, upgradeable up to some extent, not too expensive, powerful enough and easy/ not-too-expensive to repair in case something breaks down.
Some considerations:
-- I am more interested in torque than in speed.
-- My optimal pedal cadence is approx. 85 rpm.
-- I weight ~138 lb or ~63 kg.
-- Ideally I want to try to order from one distributor to save as much as possible in shipping and taxes. Here in Germany things get expensive really fast.
-- Unfortunately I don’t really have $1000 or so to spend in a MAC system, although I would love to… someday…
Question:
How do you calculate the real load speed of the motor? I plan to use a 1:2 reduction ratio hoping to have a similar cadence to mine. Would that ratio be good enough?
Features I need:
-- The motor needs to be powerful enough to assist me with hill that are ca. 30° while I also pedal. Also it needs to be able to pull uphill a trailer with 20-40kg.
-- The bike need to be able to go through very uneven off-roads with steep slopes.
-- Freewheeling
-- Quietness. I hate whinny motors (I think I don’t mind a deep motor growl as long it is not very loud)
-- Smoothness. It should work with smooth transitions between PAS levels, etc.
-- The motor should be powerful enough to be mounted in the rear wheel if need and still be able to provide considerably hill assist (although not for 30° hills anymore)
-- The motor needs to be compact enough to mount it as mid-drive
-- Ideally I would like to be able to replace the battery myself, thats why I am considering a Headway pack. If you think there are better/ very-strong reasons to use a Panasonic pack, instead of a headway pack, feel free to share your thoughts.
The components I am considering for my build are:
-- The Cute 201 Q128H https://bmsbattery.com/ebike-kit/775-q128h-36v800w-rear-driving-ebike-hub-motor-ebike-kit.html (from BMS). I do not know if I want the cassette (500W) or the freewheel (800W) version yet. Just curious, do you think a normal Q100 will be enough for this application?
-- This S12S torque simulation sine-wave controller (from BMS) https://bmsbattery.com/ebike-kit/552-s12s-500w-torque-simulation-sine-wave-controller-ebike-kit.html?search_query=s12s&results=13
-- This 36V 10Ah (Max. 30A continuous) https://bmsbattery.com/ebike-battery/114-36v10ah-lifepo4-battery-38120-battery-pack-with-carrier-headway-battery.html Lifepo4 battery with the charger and rack included (from BMS). I also think the battery would be able to provide more than enough juice for the mid drive and the gears of the bike, since I would only activate the throttle via BeamTS sensor in the very steep hills and the rest of the time I plan to ride the bike only with the PAS levels.
-- An dditional charger for the battery (I have read that the BMS charger are not good, if you know a good charger for 36V Lifepo4 that is not as expensive as the Cycle Satiator would you mind sharing the info here?).
-- The S-LCD3 display to program the controller (from BMS). https://bmsbattery.com/ebike-kit/670-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html#/310-color-white
-- A 12 Magnet cadence sensor (from BMS). https://bmsbattery.com/ebike-parts/504-pas-pulse-padel-assistant-sensor-with-12-pcs-magnets-parts.html
-- Speed sensor (from BMS). https://bmsbattery.com/ebike-kit/661-king-meter-speed-sensor-ebike-kit.html
-- E-brakes (from BMS). https://bmsbattery.com/ebike-parts/52-brake-grip-parts.html
-- BeamTS torque sensor for the throttle signal (does anybody knows where to buy it? I have been looking for distributors but I was not able to find many options). Grin is listed as a distributor but the item has been for a long time out of stock in their website.
-- I need to build my own brackets for the motor and the BeamTS sensor.
-- A on/off switch for connection/disconnection of the BeamTS torque sensor to/from the controller.
As I understand it, the current limiting feature using the S12S controller applies only to the PAS and not to the throttle (which would give instead the maximum current of the controller, right?).
I want to connect the BeamTS to the controller whenever I need immediate assist and full power (for example starting from a stand still position when going uphill). When I do not need the immediate assist I would then drive only with the PAS assist levels. Therefore, ideally I would like to restrict the max. amps of the S12S with the display to half of its maximum (setting the C5 parameter value to a value of 03 or “maximum controller’s current” divided by 2) and use the 5 different assist levels along with this restricted current.
Question:
Which maximum current value do the 5 different PAS assist levels take as reference?
Do they follow the restricted current determined by the C5 parameter value and then divide it by 5 so that the assist is:
-- 0% of the C5 parameter current @ assist0
-- 20% of the C5 parameter current @ assist1
-- 40% of the C5 parameter current @ assist2
-- 60% of the C5 parameter current @ assist3
-- 80% of the C5 parameter current @ assist4
-- 100% of the C5 parameter current @ assist5
-- I am assuming the 5 different PAS levels increase/decrease the current in increments of 20% per assist level. Is this percentage how the amount of assist is divided?
Or do they simply divide the “maximum controller’s current” by 5 giving:
-- 0% of the maximum controller’s current @ assist0?
-- 20% of the maximum controller’s current @ assist1?
-- 40% of the maximum controller’s current @ assist2?
-- 60% of the maximum controller’s current @ assist3?
-- 80% of the maximum controller’s current @ assist4?
-- 100% of the maximum controller’s current @ assist5?
-- Is there any other way to restrict the throttle max. current using the 5 different assist levels with the current configuration?
I was also considering, as an alternative, to match the motor to the following controllers:
-- 6FET Lyen mini monster programmable controller. http://www.lyen.com/
-- 9FET Infineon programmable controller from Em3ev. http://em3ev.com/store/index.php?route=product/product&path=41_38&product_id=79
-- What are your thoughts in general about these two instead of the S12S controller when used with the Q128H or the other cute motors?
-- Would they also allow current limiting/control for both the PAS and the throttle? And would that only be possible in combination with a Cycle Analyst?
I think that is pretty much it.
Any opinions, recommendations and constructive criticism are very welcome. I hope you also enjoy the build and hope it can be helpful to others as well.
Thanks!
