Everything the firmware lets you set, section by section: what each setting does, how it feels on the bike and where the limits are. The numbers are the firmware's defaults; all of it changes in the app while the bike stands.
The mode is picked with the stock switch on the right bar block: up — SPORT, middle — ECO, down — DAILY. On the move the limits glide to the new mode in 0.3 s, without a jolt.
Each mode has three limits. Phase current sets the torque: while there is voltage to spare, the pull is constant. Power takes over above the "knee": from there torque falls with speed while the power holds. The speed ceiling is soft: over the last 5 km/h the pull fades to zero. It is not a brake — downhill the bike can go faster.
Gentle response and economy.
Everyday balance of pull and control.
Maximum output and speed.
The firmware's defaults. Current — no more than the board's design current, 800 A. Power — no more than the battery's rating: Ultra24 18 kW (230 A), Ultra25 28 kW (350 A), your own pack — full voltage × rated current; the app won't let you set more. Temperature derating of the motor and the controller applies in every mode.
The pull off the line and up to the knee. 0 — no mode limit, only the absolute ones. The app shows the torque estimate at the motor and at the wheel right away.
On the bike: more current — a harder launch and an easier front wheel; less — a softer start, longer-lived tyre and chain.
Power at the motor: the firmware works it out from the currents and voltages every tick and trims the current when the limit is reached.
On the bike: decides how the bike pulls at mid and high speed. A lower limit — calmer acceleration past the knee, a cooler battery and motor.
A soft limit: full pull up to "ceiling minus 5 km/h", zero at the ceiling. 0 — no mode limit.
On the bike: the bike leans into its speed smoothly, no cut-out; under load it settles just below the ceiling.
How fast the limits change when you switch on the move. Disarmed — instantly.
On the bike: SPORT → ECO on the move — the pull drops smoothly, no hole.
The grip sets torque, not speed: grip position → curve → ramp → the mode's current. There are three profiles, shared by ECO, DAILY and SPORT, switched from the stock dash menu (item F) or in the app. A new profile applies at once; the ramp smooths the change.
How grip travel turns into torque. Every curve runs through 0 and 100 %: full throttle always gives the mode's full current.
On the bike: the curve decides where on the grip the pull lives. A soft one is easier to meter on slippery ground and technical sections; a sharp one answers from the first degrees.
Positive — a soft start, negative — an aggressive one. Not used by the linear curve.
On the bike: k = 2…3 is a calm grip for mud and rocks; a negative k suits racing and climbs, where the pull is needed at once.
How fast the command may rise from 0 to 100 %. 0 — no limit.
On the bike: how softly the pull arrives when you snap the throttle open. Shorter — a harder hit on the chain and easier wheelspin; longer — softer and more predictable.
How fast the command falls from 100 % to zero.
On the bike: shorter — the pull goes at once and the bike pitches harder when you roll off; longer — a smooth roll-off that doesn't upset the suspension.
The first part of the grip travel the motor ignores.
On the bike: the bike doesn't creep from grip play or a shaking hand over bumps.
The last few per cent of travel already count as 100 %.
On the bike: full throttle is guaranteed at the stop, even if the grip falls a little short.
The ramps delay only the throttle. Speed and power limits, ASR and the brake act at once. The profile at switch-on is set in the app: TP1, TP2 or TP3.
Two levels and two ramps. To the controller the brake lever is the brake-light signal: the motor braking force comes from the level, not from how hard you squeeze. The levels change in the app and in the dash menu (items B and E).
Motor braking strength, B5 is 30 % of phase current. Without regen the brake only takes the drive away: you can't ride "against the brake", and the battery isn't charged.
On the bike: touch the brake — the throttle stops pushing; with regen the motor brakes the bike as well.
Motor braking with the throttle closed. Works only with regen on.
On the bike: like engine braking: E0 — a free coast, E5 — the bike slows noticeably the moment you roll off.
How fast the motor braking builds and lets go.
On the bike: a soft entry into braking without locking the rear wheel.
Turned on only for a battery that accepts charge. The charge current stays within the rating (Ultra24 100 A, Ultra25 150 A). It stops at 95 % of the full voltage and fades out between 5 and 3 km/h.
On the bike: braking that returns energy; on a full pack it weakens — the firmware protects the battery.
ASR compares the front and rear wheel speeds from the stock sensors — 42 pulses a turn, recomputed every millisecond. Slip λ = (rear − front) / front. Below the threshold the throttle is as it is; above it, torque is multiplied by k and reaches the minimum at the "full cut".
On and off — a long press of the ASR button on the bar (0.7 s). A double press — the next level, A1 → A2 → A3; a single press shows the level. The choice is saved at once; the level can also be picked in the dash menu (item A) or in the app.
Soft. Allows noticeable slip and cuts shallow — dry tarmac, racing.
Medium. Balanced: steps in on clear wheelspin.
Strong. Acts early and nearly to zero — wet, mud, ice.
The slip at which the cut begins.
On the bike: a lower threshold — ASR steps in earlier; a higher one lets the wheel work and clear the mud.
The slip at which torque reaches the minimum. At least 1 % above the threshold.
On the bike: close to the threshold — a sharp cut; further away — smooth, almost unnoticed.
How much torque is left in heavy wheelspin. 0 % cuts to zero: the wheel stops.
On the bike: a higher minimum keeps the bike driving through wheelspin; a lower one nearly stops the wheel so it grips.
Cut — how fast torque falls from full to the minimum; return — how fast it comes back. Shared by all levels.
On the bike: a fast cut catches wheelspin, a slow return keeps it from starting again.
A standing front wheel with the rear spinning is wheelspin too: torque drops to the minimum and holds until the throttle is closed; lifting the front wheel makes ASR cut as well. If the rear sensor goes silent, ASR takes the rear speed from the motor. Switch a faulty front sensor off with the ASR button. ASR is off in crawl and reverse. Accuracy depends on the wheel diameters: the firmware measures the front one itself from the motor while coasting.
The firmware runs on the Ultra Bee's stock controller. Its power stage is three half-bridges: 24 Magnachip MDY10N025RH MOSFETs, four in parallel in each of the six switch positions.
| Power switches | 24 × Magnachip MDY10N025RHN-channel, 100 V, M2PAK-7P package with a separate driver-source pin |
|---|---|
| Layout | 6 positions × 4 switches in parallel8 switches per phase |
| On-resistance per switch | 2.2 mΩ typ., 2.5 mΩ max at 25 °Ca group of four — 0.63 mΩ at most |
| Rated switch current | 240 A package, 306 A silicon at 25 °C217 A at a 100 °C case; 960 A pulsed; junction up to 175 °C |
| A position of four | 868 A at a 100 °C case4 × 217 A, from the switch datasheet |
| Phase current in the firmware | up to 800 Athe board's design current |
| Gate drivers | 6 × IR2127 |
| Current sensors | 3 ring sensors on the phase wiresmeasuring range ≈ ±1550 A |
| DC-link capacitors | 7950 µF, 120 V |
| Processor | NXP S32K142, Cortex-M4F, 112 MHz |
| Current loop | 32 kHztwo updates in every 16 kHz PWM period |
Electrical power into the motor is P = 1.5 · U · I, with U and I the phase voltage and current amplitudes. Using the full voltage of a 74 V (20S) pack, U ≈ 40.8 V, and at 800 A that is ≈ 49 kW; on a fully charged pack (86 V) — ≈ 57 kW. The battery has to deliver about 660 A for it.
This is a calculation from the switch datasheet and the maximum modulation, not a measurement on the bike. In practice the battery sets the power: the firmware won't give a mode more than its rating — Ultra24 18 kW, Ultra25 28 kW, your own pack voltage × current. A mode limit in the firmware goes up to 60 kW. Heat keeps 800 A from lasting, which is why the current derates with the motor and controller temperatures.
Engages in READY when the bike is almost still (±2 km/h by the motor and the front wheel) with the throttle closed: hold R/T for 0.5 s. The throttle is linear in reverse. Let R/T go — a coast, then forward again, no new READY needed.
On the bike: 15 % is about 120 A at 800 A: enough to roll back gently. Hard uphill or out of a rut — raise it to 25–30 %.
Low speed for the trail and manoeuvres: the throttle pulls with full torque but no faster than the level's ceiling. To switch on — in READY, standing, throttle closed: hold READY 1 s; double press — the next level. ASR is off in crawl.
On the bike: full torque up to three quarters of the ceiling — rocks, roots and steep climbs at walking pace, without metering the throttle.
0 — all the available torque, whatever the ECO, DAILY or SPORT mode; the temperature and other protections still apply.
On the bike: limit it if the wheel breaks loose too easily in crawl.
Hold the brake 2 s at a standstill in READY — the throttle no longer drives the bike, the dash shows "H". Let the brake go — the drive is back.
On the bike: a throttle nudged at a stop won't jerk the bike.
ASR + READY for 2 s with the bike still: brake B, coast E, ASR level A, tip-over sensor C, side stand P, throttle profile F, crawl level L. After 10 s without a press the menu closes and saves.
On the bike: change the setup at the track without a phone.
Hold READY 0.5 s; optionally only with the brake; leave READY after 0–3600 s idle. It needs the key, the kill switch in run, the bike upright and the throttle closed.
On the bike: the bike won't move until you clearly switch it on.
Motor profiles (stock Ultra Bee 2025, Sotion GTS01 Pro) or your own: the firmware measures the resistance, inductances and flux linkage itself. The encoder, the switch dead time and the temperature sensor are calibrated from the app; the setup wizard has 7 steps.
Ultra24, Ultra25 or your own: 10–24S, currents from the datasheet. With the stock pack — cell voltages, temperatures, cycles and the serial over CAN; without a BMS the stock dash shows the charge from the voltage.
New versions install from the app. Every build is signed and bound to your controller.
A dashboard for your bars — portrait and landscape, telemetry, peaks, CSV recording, rides with the route on a map, GPX and CSV export. iPhone and Android.
There are two kinds of reaction. A soft stop: zero current, the bike coasts under control until the motor stops, then the bridge is disarmed — the response to overheating, overvoltage, a faulty current sensor or throttle. Every other fault disarms the bridge at once. A fault stays until it is cleared, and its cause goes into the log.
Checked every current-loop tick: 200 µs above the threshold and the outputs switch off in the same tick; at high revs the drive goes into a controlled coast. The default threshold is 90 V (90 % of the switch rating), and no more than "the voltage at switch-on + 12 V".
If the voltage rises 3 V above the switch-on value, the motor puts the energy back into motion; braking current is forbidden on the move.
Only when allowed, only up to 95 % of the full voltage, the charge current within the battery's rating.
A bus outside 10–130 V — no running; below 10 V — a fault.
The current vector is limited in magnitude, rises no faster than 5000 A/s, and the limit falls with temperature.
Every tick the sum of the three phases is checked against zero: more than half the ticks bad within 10 ms — a soft stop. Before switch-on the sensor zeros are checked: drift over 3 A — no switch-on.
Current derates from 100 °C, down to the minimum at 135 °C, a trip at 150 °C. An open or shorted sensor reads as overheating.
Current derates from 65 °C down to the minimum at 85 °C.
Speed drifting from the command and rising under current for 30 ms — an immediate trip. Revs 20 % over the limit — the same.
The angle is confirmed by the encoder and an observer; a tracking error over the limit trips the drive. Without a confirmed angle the bike won't switch on.
A signal outside its window — zero torque, a soft stop. Switch-on only with the throttle closed.
If the fast or the slow loop hasn't advanced within 5 ms, the bridge is disarmed at once. Numeric errors and a stack overrun stop the drive too.
The key, the kill switch, the tip-over sensor; optionally the side stand and READY only with the brake.
Written only while standing, with the bridge disarmed, through a before → after review. Kept in two FRAM slots with a CRC: a power cut won't corrupt them.
If the link to the phone is lost for over 0.5 s, the controller cuts the current.
Every fault with a snapshot of the drive at the moment it tripped — 32 entries in FRAM.
Before installing and before every start — an RSA-2048 signature, a SHA-256 hash and the binding to the chip. The flash is read-protected.
The whole package is checked before the old version is erased. If the transfer breaks, the previous firmware runs; if the install fails, it is retried at the next power-up.
Briefly, without the internals. At the core are methods from research on synchronous motor control and from industrial servo drives, brought to work on a motorcycle's stock controller.
Two measurements and two voltage updates in every PWM period.
The current is computed a step ahead to cover the delay; a disturbance observer makes up for the model's error.
Measurement and voltage output are brought to one instant — the angle stays accurate at high revs.
Maximum torque per amp for a motor with unequal axis inductances — a closed-form solution.
Feed-forward from the voltage ellipse: the motor runs past its base speed without a dip in pull.
Non-linear, current-dependent, with an automatic calibration on the spot.
More voltage to the motor without disturbing the current measurement.
The encoder and an active-flux observer in one tracking loop.
The gains are refined on the move by least squares.
Resistance, inductances and flux linkage — by multi-frequency injection and a dead-time-aware regression.
Slip from both wheels, with the motor as a backup speed source.
RSA-2048, SHA-256 and binding to the chip's unique ID — from the boot loader to over-the-air updates.
Off-road and closed tracks only. Changing the controller's settings — power, current, speed — can make the motorcycle non-compliant for public roads and void its warranty. Check new settings standing still, with the wheel lifted, in full gear.
Wrong settings can cause a jolt, the bike speeding up by itself, loss of traction or a drive fault while riding. That can end in a fall or a crash: injury, disability, death — yours and others'.
Wrong currents, voltages, dead time, angles or frequencies can break down the power switches and short the battery through the controller — with a fire. A weakened protection does not trip.
The firmware and the app are provided “as is”, without any warranty; by using them you accept the risk that comes with it. ALEX_V LABS is not liable for injury, damage or fire — to the extent the law allows.