Ryan Saldanha
1 µW
- Joined
- Aug 30, 2019
- Messages
- 4
EBike Specs:
I have custom built a mid drive ebike with a frame mounted motor and controller (components linked at bottom). I built a 48V 13S battery pack with 3 cells in parallel. A 48V BMS is installed on the battery. The battery is connected to the controller with an XT60 connector. All the battery components including the compatible 48V charger were purchased from VRUZEND.com. I installed a twist throttle that came with the motor and controller.
Issue:
When I ride the bike and open the throttle, the motor drives the rear wheel, accelerating the bike, but as soon as the bike reaches a few MPH all power is lost and the system shuts down. The motor stops and the throttle display fades to black, suggesting that the battery as fully stopped supplying current. If I very lightly feather the throttle, I can sustain the power nearly indefinitely, but if the throttle opens too much, only a fraction of its full range, the bike loses power. When I raise the back wheel of the bike off the ground and open the throttle, the back wheel reaches very high RPMs and can be sustained indefinitely with almost a fully opened throttle, but the bike does shut down in a few seconds if the throttle is fully opened. In the both the test with load and without load, I can use the system again by disconnecting and reconnecting the connector between the battery and controller.
Current Theories and Questions:
Because the power is lost at a certain level of throttle use, it seems the issue could be related to amp draw, suggesting that the BMS may be shutting down the battery when too many amps are being drawn. The BMS is rated for 30A continuous draw while the controller is rated for 33A continuous draw. I have heard that this should not be a major issue, because the BMS should be able to temporarily handle 33A and all 33A are not being drawn continuously for general use. Is this reasonable? What are the most effective methods of measuring amp draw from the battery? Could I install a resistor between the connectors and then measure the voltage drop over the resistor? Will a general multimeter be able to measure between the positive terminal and positive lead of the battery measure the draw?
I have measured the voltage of the battery as the motor is running with the wheel off the ground and the power is lost with the voltage dropping from around 47V to 45-46V which I do not believe is enough for the BMS to shut down the battery, correct?
What are the other variables that may cause this issue? Is there a possibility of the electrical components in the controller having issues? Is it possible that the connectors are not the right gauge to support the current coming from the battery? I would appreciate any thoughts on this issue.
Components:
Motor/Controller/Throttle- https://www.amazon.com/Electric-Brushless-Complete-Controller-Motorcycle/dp/B07G2LZHD8/ref=sr_1_4?keywords=kunray+ray+ebike+motor&qid=1567786124&s=gateway&sr=8-4
Battery Cells- https://vruzend.com/product/set-of-two-2-samsung-inr18650-30q-3000-mah-18650-battery-cells/
BMS- https://vruzend.com/product/48v-13s-battery-management-system-bms/
Charger- https://vruzend.com/product/48v-lithium-ion-battery-charger-3-amps/
Connector: https://vruzend.com/product/xt60-connectors-with-14awg-silicone-wire-leads/
I have custom built a mid drive ebike with a frame mounted motor and controller (components linked at bottom). I built a 48V 13S battery pack with 3 cells in parallel. A 48V BMS is installed on the battery. The battery is connected to the controller with an XT60 connector. All the battery components including the compatible 48V charger were purchased from VRUZEND.com. I installed a twist throttle that came with the motor and controller.
Issue:
When I ride the bike and open the throttle, the motor drives the rear wheel, accelerating the bike, but as soon as the bike reaches a few MPH all power is lost and the system shuts down. The motor stops and the throttle display fades to black, suggesting that the battery as fully stopped supplying current. If I very lightly feather the throttle, I can sustain the power nearly indefinitely, but if the throttle opens too much, only a fraction of its full range, the bike loses power. When I raise the back wheel of the bike off the ground and open the throttle, the back wheel reaches very high RPMs and can be sustained indefinitely with almost a fully opened throttle, but the bike does shut down in a few seconds if the throttle is fully opened. In the both the test with load and without load, I can use the system again by disconnecting and reconnecting the connector between the battery and controller.
Current Theories and Questions:
Because the power is lost at a certain level of throttle use, it seems the issue could be related to amp draw, suggesting that the BMS may be shutting down the battery when too many amps are being drawn. The BMS is rated for 30A continuous draw while the controller is rated for 33A continuous draw. I have heard that this should not be a major issue, because the BMS should be able to temporarily handle 33A and all 33A are not being drawn continuously for general use. Is this reasonable? What are the most effective methods of measuring amp draw from the battery? Could I install a resistor between the connectors and then measure the voltage drop over the resistor? Will a general multimeter be able to measure between the positive terminal and positive lead of the battery measure the draw?
I have measured the voltage of the battery as the motor is running with the wheel off the ground and the power is lost with the voltage dropping from around 47V to 45-46V which I do not believe is enough for the BMS to shut down the battery, correct?
What are the other variables that may cause this issue? Is there a possibility of the electrical components in the controller having issues? Is it possible that the connectors are not the right gauge to support the current coming from the battery? I would appreciate any thoughts on this issue.
Components:
Motor/Controller/Throttle- https://www.amazon.com/Electric-Brushless-Complete-Controller-Motorcycle/dp/B07G2LZHD8/ref=sr_1_4?keywords=kunray+ray+ebike+motor&qid=1567786124&s=gateway&sr=8-4
Battery Cells- https://vruzend.com/product/set-of-two-2-samsung-inr18650-30q-3000-mah-18650-battery-cells/
BMS- https://vruzend.com/product/48v-13s-battery-management-system-bms/
Charger- https://vruzend.com/product/48v-lithium-ion-battery-charger-3-amps/
Connector: https://vruzend.com/product/xt60-connectors-with-14awg-silicone-wire-leads/