Got my first ebike, trying to understand speed limiter mechanism

Rafc

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Hello Everyone!

I have recently bought my first ebike. I am ovrtall happy with the performance but a little puzzled how the current is being cut-off when the bike reaches top speed around 38 km/h. This top speed is lower around 35 km/h when the battery is half-empty, and higher >40 km/h if the bike is stationary and I just lift the rear wheel in the air. But in all cases the current drops to very low values once the top speed is reached.

I have checked the speed limit in the display is maxed out at 60 km/h. I have tried the trick with lowering the wheel size, I have tried increasing the current cut off from 20A to 22A, but not much has changed.

Can anyone here explain to me what is the mechanism behind the current suddenly dropping from max value to low value once the top speed is reached? Any idea how can I remove this limitation?

I feel that the 48V 17.5Ah battery, 22A controller and 1000W rated motor combination still have more juice to push the top speed further, just don't know how.

Thanks in advance!

Display comms protocol: https://electricbike.com/forum/foru...62496-dmhc-tc488-communication-protocol/page2

The photo of the bike and controller: Website showing the bike specs: https://richbitebike.com/product/ri...ack-yellow-electric-fat-tire-snow-bike-ebike/

A picture showing how the controller is connected to other elements of the bike here: https://richbitebike.com/wp-content/uploads/2019/07/RT-022-Controller-Connection-Diagram-print.pdf
 
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alaskawet

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Perhaps in the programming you dont have it set high enough? I have one that goes from 1-10. Ten being highest. Mines a kt35 controller. Maybe there similar in operation?
 

Rafc

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Hello Everyone!

I have recently bought my first ebike. I am ovrtall happy with the performance but a little puzzled how the current is being cut-off when the bike reaches top speed around 38 km/h. This top speed is lower around 35 km/h when the battery is half-empty, and higher >40 km/h if the bike is stationary and I just lift the rear wheel in the air. But in all cases the current drops to very low values once the top speed is reached.

I have checked the speed limit in the display is maxed out at 60 km/h. I have tried the trick with lowering the wheel size, I have tried increasing the current cut off from 20A to 22A, but not much has changed.

Can anyone here explain to me what is the mechanism behind the current suddenly dropping from max value to low value once the top speed is reached? Any idea how can I remove this limitation?

I feel that the 48V 17.5Ah battery, 22A controller and 1000W rated motor combination still have more juice to push the top speed further, just don't know how.

Thanks in advance!

Display comms protocol: https://electricbike.com/forum/foru...62496-dmhc-tc488-communication-protocol/page2

The photo of the bike and controller: Website showing the bike specs: https://richbitebike.com/product/ri...ack-yellow-electric-fat-tire-snow-bike-ebike/

A picture showing how the controller is connected to other elements of the bike here: https://richbitebike.com/wp-content/uploads/2019/07/RT-022-Controller-Connection-Diagram-print.pdf

Thank you for a suggestion! I have already checked the speed limit that can be set in the controller, I can choose from 20-29 and 60 km/h. I have it set to 60.
 

alaskawet

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That setting i believe is for top speed allowed by controller. There should be another setting for power output. There's a utube video of settings for lcd8h which i have. Very good video. Maybe its similar or thers one available for your exact controller? Took me about 4 hours getting mine the way i want..should have asked a kid..probably would have taken 15 mins..
 

alaskawet

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20200911_232101.jpg
 

alaskawet

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heres a picture of mine. Hope it helps. If not,keep asking questions. Im sure somone knows somwere...
 

Rafc

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That setting i believe is for top speed allowed by controller. There should be another setting for power output. There's a utube video of settings for lcd8h which i have. Very good video. Maybe its similar or thers one available for your exact controller? Took me about 4 hours getting mine the way i want..should have asked a kid..probably would have taken 15 mins..

Thank you fo sharing your experience! I have only identified which parameter in the controller is a current limit, which should transfer to power. Sadly, increasing this current limit had not improved my situation - the top speed is exactly the same.
 

alaskawet

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Maybe try a 35 amp controller? Not sure if its compatible with your screen? What type of screen do you have? Little over hundo for a 35 amp controller. With my 35 amp controller 48 volt 17 mah battery and rear bafang 750 i push about 1400 watts and will do a 32 mph on flat ground. (finally tested with full battery) will still do 30 at less than half battery power. Accelerates very quickly. Any more speed probably will need higher gearing or 52-60 volt battery. I think you need more controller for what u have. My old sondors 25 amp would pull almost 28 amps full battery and about 30 mph. Either your controller isnt enough or maybe its the programming/screen?
 
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