The ASI BAC855 motor controller is a sub-compact AC motor controller built for high-power electric bikes and light electric vehicles. It runs across a 36–72 V range and delivers 70 A rated current. Peak current reaches 90 A. The controller drives brushless PMSM and BLDC motors, so it suits 48 V and 72 V conversion builds alike.
Internally, the BAC855 converts DC battery current into three-phase AC current. It uses field oriented control (FOC) together with an adaptive sensorless algorithm developed by ASI. As a result, no rotor position sensor system is required. The controller also runs its own auto-tuning routine and adapts its parameters to the connected motor.
This model sits at the top commercial tier of electric bike drives. Consequently, it supplies more power than the smaller BAC800. The ASI BAC800/855 wiring harness is sold separately. Purchasing this item also requires a remote programming session.
Key Benefits
- Field oriented control – precise current regulation turns the rotor smoothly from a standstill.
- Adaptive sensorless start – the motor starts without Hall sensors, which simplifies installation.
- Up to 120% torque – the controller reaches up to 120% of rated locked-rotor torque.
- Auto-tuning – it identifies the parameters of the connected motor on its own.
- 90 A peak current – short bursts climb above the 70 A rated figure.
- IP65 rated housing – with sealed connectors, protection rises to IP67.
- Wide voltage window – one unit covers 36 V, 48 V, 60 V and 72 V systems.
- TTL and Bluetooth – parameters change over a wired or wireless link.
- 100% end-of-line load test – every controller is tested at the factory before shipping.
Who Is This Controller For?
The BAC855 targets high-power electric bikes, electric scooters and light electric vehicles. It fits any conversion built around a brushless PMSM or BLDC motor. Battery systems from 36 V to 72 V are supported. Therefore, 48 V and 72 V conversion builders choose it often.
Beyond personal vehicles, it also appears in industrial and utility light electric vehicles. The unit is aimed at experienced builders and workshops. In addition, manufacturers developing their own drive system use it as a platform. Buyers who prefer the lower-current BAC800 should note the power difference between the two models.
Technical Specifications
| Model | ASI BAC855 |
| Type | AC motor controller / inverter |
| Rated voltage | 36–72 V |
| Rated current | 70 A |
| Peak current | 90 A |
| Control method | Field oriented control (FOC) |
| Sensorless start | Adaptive |
| Auto-tuning | Yes |
| Torque | Up to 120% of rated locked-rotor torque |
| TTL interface | Yes |
| Additional protocols | TTL + Bluetooth |
| IP rating | IP65 (IP67 with sealed connectors) |
| Quality control | 100% end-of-line load test |
| Housing | Sub-compact |
| Wiring harness | ASI BAC800/855 – sold separately |
Why Choose the ASI BAC855?
ASI (Accelerated Systems Inc.) designs and builds motor controllers and drive electronics exclusively. For that reason, the BAC series is a narrowly specialised product line. The BAC855 is the stronger sibling of the BAC800 model.
Every unit passes a full load test rather than a simple circuit measurement. The factory therefore verifies operation under realistic conditions. Its IP65 enclosure also allows mounting in an exposed frame position. Sensorless operation removes the Hall sensor wiring and its failure point, yet torque still reaches up to 120% of locked-rotor torque.
Frequently Asked Questions
What are the rated and peak currents of the ASI BAC855?
- Rated current is 70 A.
- Peak current is 90 A.
Which motors does the BAC855 work with?
- Brushless PMSM motors.
- Brushless BLDC motors.
- No Hall sensors are needed, thanks to adaptive sensorless start.
Which vehicles is the BAC855 suitable for?
- High-power electric bikes and electric scooters.
- Light electric vehicles, including industrial and utility models.
What battery voltages does it support?
- Any system between 36 V and 72 V.
- 36 V, 48 V, 60 V and 72 V packs all run on one unit.
How is the BAC855 programmed?
- Over the TTL interface by wire.
- Over Bluetooth wirelessly.
- A remote programming session must be purchased with the controller.
How does the BAC855 differ from the BAC800?
- The BAC855 supplies more power than the BAC800.
- Both share the same ASI BAC800/855 wiring harness.
Is a wiring harness included?
- No. The ASI BAC800/855 harness is sold separately.
What is the IP rating?
- IP65 as standard.
- IP67 when sealed connectors are used.
The ASI BAC855 combines a sub-compact housing, 70 A rated output and adaptive sensorless FOC in one unit. Order the ASI BAC800/855 harness and a remote programming session alongside it to complete your build.
There are no reviews yet.