Just circling back to share some improvements I’ve made and a few things I’ve come to realize:
a) Speed Ratios ≠ Field Weakening
There’s a common misconception that the
Speed Ratios settings in Fardriver correspond to field weakening. They do
not. These values control current draw at various RPM levels—effectively shaping the torque curve.
Setting them all to 100% just increases current across the entire RPM range, which can stress the system unnecessarily.
To optimize performance and efficiency, ratios should be tuned based on:
- Motor specs (e.g., Kv, efficiency range)
- Battery capability (voltage sag, discharge current)
- Personal preference (torque vs. top speed)
b) Custom 12V Battery + Alarm
Built a 12.6V / 17Ah lithium pack to run a standalone bike alarm. Initially tried to retain the OEM alarm by stepping up 12V to 48V using a DC-DC converter, but it drew too much current—battery drained in <4 days.
Switched to a universal 12V alarm wired directly to the new battery.
- Lost remote start / key switch lock features (those require 72–84V from main pack)
- Gained tilt & impact detection
- Alarm triggers loud siren on movement/tampering
After ~2 weeks of standby, the battery still reads 12.2V. Works as a clean low-power security solution.
c) 72V Battery Upgrade (Amorge 50Ah w/ ANT BMS)
Installed a new 72V 50Ah Li-ion pack (Amorge) with ANT BMS:
- 200A continuous
- 350A peak
Overkill for my current hub motor (rated ~2600W), but I plan to upgrade later.
Controller limits set to:
- MaxLineCurrent = 190A
- MaxPhaseCurrent = 350A
Results:
- Noticeable torque increase
- Top speed increased from 60-65 km/h → 70 km/h
- Voltage sag dropped to ~3–4V under hard acceleration
Previously, voltage drop at full throttle was significant, maybe even more than 10v (especially <80V).
d) Fuse Removal
Amorge advised removing my inline 80A fuse, stating the BMS handles overcurrent protection.
While technically correct, I’m not fully confident in relying on software/BMS-only protection in case of controller failure or short.
For now, I’ve removed the fuse but monitoring it closely.
Would appreciate any insight from others running high-current systems—do you keep inline fuses or trust BMS protections alone?
e) Field Weakening (DeepWeak) Problem
Can’t enable field weakening on my Fardriver controller. The DeepWeak parameter is locked at 0 - Normal. Changing it to 1 (Field Weakening ON) and saving causes it to immediately revert to 0. I have already changed WeakCharacter to 0 - Fast and weak response to 3.
Siaecosys feedback:
This is because your motor and controller are not properly matched, the RPM is set too high, and the current is set too high. A 50A/200A (bus/phase) controller is sufficient for a 2600W peak power motor.
Additional info:
- Rated RPM at 72V = 670 (as per Siaecosys)
- AutoLearn result at 84V = ~980 RPM
So far, I suspect the mismatch is causing FW lockout in firmware. I will try lowering RPM to 670 to test if that unlocks the DeepWeak option. To be honest, i dont want to touch the bus/phase Amps but maybe i will to see if i can enable FW.
If anyone has successfully enabled FW on similar setups—or has thoughts on fuse protection and current tuning—I’d appreciate your input.