Technical Q&A

This guide answers common technical questions about ASI BAC motor controller configuration and integration.

Voltage Protection

How are voltage thresholds specified?

All voltage thresholds are expressed as a percentage of Rated System Voltage (Address 70).

What are the foldback voltage addresses?

Example calculations for a 14S (58.8V nominal) system

Regenerative Braking

How is the battery-side regen limit specified?

Parameter: Regeneration battery current limit

Units: Percentage of rated motor current

Formula:

Regen limit % = Peak regen current / (Rated motor power ÷ Rated system voltage)

Example: For 45A regen on a 2880W system at 48V:

45A / (2880W / 48V) = 45A / 60A = 75%

What happens when both engine braking and manual regen are active?

As of firmware 6.014, when both engine braking and analog regenerative braking are active simultaneously:

The controller gives priority to whichever source is commanding the higher braking torque.

How do I configure the braking torque ramps?

What is the low-speed cutoff for regen?

Parameter: Regen brake speed

• Sets the minimum speed threshold for effective regenerative braking
• Below this speed, regen becomes ineffective due to insufficient back-EMF
• Use plug braking (Features2 bit 3) to supplement at low speeds

Engine Braking

How do I enable engine braking?

1. Set Features bit 13 to enable
2. Configure Regeneration battery current limit
3. Set Maximum braking torque (start at 10%)
4. Configure Engine braking torque as percentage of max braking torque

What firmware version supports engine braking?

Engine braking is available in firmware 6.014 and later.

Analog Brake Inputs

What are the typical voltage values?

How do I configure the brake input?

Which inputs can I use for braking?

• Brake1/Analog input 2
• Brake2/Analog input 3

Select from: Brake2, Brake1, Network, Throttle, or ABMS as the regen brake source.

Battery Disconnect Protection

What happens if the battery disconnects during regen?

Fault Response:

• Slow over voltage fault (Flash code 1-1) triggers when filtered battery voltage exceeds threshold
• Faults typically require power cycle to clear

How do I protect against this?

1. Add bulk capacitors for temporary power during disconnection
2. Implement undervoltage fault detection for graceful shutdown
3. Use inrush limiting during reconnection

Dual-Battery Systems

Can I use OR-ed battery packs?

Yes, but with important considerations:

• Current must flow bidirectionally between controller and DC source
• Simple series diodes are unsuitable as they block regenerative current
• Use ideal diode bridges with N-Channel MOSFETs
• Or use contactors with polarity detection

What are the bus dynamics with dual batteries?

• Controller sees a stiff bus held by whichever pack has higher voltage
• Verify maximum allowed impedance during regen
• Ensure charge-inhibit signals are properly routed from each BMS

Temperature Foldbacks

How do temperature foldbacks affect regen?

Battery Foldbacks:

• Can be voltage-based, SOC-based, or I²T-based
• High battery voltage foldback specifically reduces regen current
• Warning bit 8 activates when voltage exceeds starting threshold

Controller Temperature Foldback:

• Fixed parameters, cannot be modified by users
• Monitors powerboard (MOSFETs) and DSP temperatures
• Progressively reduces current as temperature rises

How do I configure motor temperature protection?

1. Activate Features bit 5 (Motor temp sensor enable)
2. Select Motor temperature source
3. Input voltage values at six temperature points (0°C, 25°C, 50°C, 75°C, 100°C, 125°C)

Network Control

Can I control regen via network?

Yes. Set Regen brake source to "Network" and use:

CANopen:

• Remote Maximum Braking Current parameter
• Remote state command (set to 2 for Run)
• Heartbeat/watchdog required

MODBUS:

• ASI Modbus Protocol Rev 1.22
• CRC16-Modbus for data integrity

What telemetry is available?

Register Addresses:

Fault Handling

How do I read flash codes?

The LED uses dual-digit flash patterns:

1. First digit flashes
2. Short pause
3. Second digit flashes
4. Long pause
5. Pattern repeats

Example: "1-1" = one flash, pause, one flash, long pause

What does Flash Code 1-1 mean?

Flash code 1-1 indicates Slow over voltage fault - filtered battery voltage exceeded threshold for more than 1 second.

How do I clear faults?

Most faults clear by:

1. Power cycling the controller
2. Addressing the triggering condition (temperature, voltage, current)

Pre-Charge Requirements

Do I need a pre-charge circuit?

Recommended for systems with significant DC-link capacitance.

Methods:

1. Pre-charge resistor + contactor (recommended)
2. NTC thermistor with bypass relay
3. Soft-start circuit with MOSFETs

What is the pre-charge sequence?

1. Initial power flows through resistor, limiting inrush
2. Capacitors charge gradually
3. Main contactor bypasses resistor for normal operation

CAN Bus Configuration

How do I terminate the CAN bus?

• CAN bus requires 120Ω termination resistors at each end
• BAC controllers have configurable internal termination
• Total bus resistance should measure ~60Ω between CAN-H and CAN-L

What is the watchdog counter requirement?

For CANopen remote control:

Send heartbeat at 100ms intervals with incrementing counter.

Reverse Feature

Can I enable reverse operation?

Yes, via multiple sources:

How does bidirectional throttle work?

Available in firmware 6.025+:

• One side of throttle for forward driving
• Other side for braking or reverse
• Configure midpoint and neutral zone width

Additional Resources

For questions not covered here, consult:

• ASI Controller Overview
• Battery Configuration
• Protection Systems
• Communication Protocols
• Software Tools