80V: SuperPower BMS and App

Use the SuperPower BMS app to check the 80V battery’s voltage, cell groups, temperature, and protection messages. The BMS handles protection and balancing automatically. Treat the app as a monitoring tool unless ONYX documents a supported adjustment for your exact battery revision.

What the App Can Change

The 80V 45Ah system described in this guide does not provide the charge-port, discharge-port, and protection-setting controls shown by some other BMS apps. A protection function existing inside the battery does not mean it is adjustable from your phone.

Do not lower a cutoff or temperature limit to make a faulty pack run. If a field or control differs on your battery, confirm its purpose with ONYX Motors before using it.

SuperPower BMS App

• SuperPower BMS - iOS
• SuperPower BMS - Android

Connect to the Battery

1. Power the battery and make sure the BMS is awake.
2. Open the SuperPower BMS app nearby.
3. Select the battery and wait for its data to load.
4. Check pack voltage, individual cell group voltages, temperature, and protection status.

The battery can be connected in the bike or checked after removal when its BMS is active. Bluetooth reception can vary with distance, the enclosure, interference, phone permissions, and device software.

If the App Will Not Connect

Check that the battery is powered, Bluetooth permissions are enabled, and the app matches the BMS. Close other BMS apps that may already be connected. Android scanning can require additional permissions depending on the system version. A successful connection with no data is different from a battery that is not found at all.

Read the App Screens

The recorded app layout has a connection or overview page, a main dashboard, and per-cell readings with voltage delta. Core metrics update while connected. Layout and access can change with app or battery revision, so identify the actual screen rather than relying only on a page number.

Normal Readings and Their Limits

A pack can look steady at rest and show a weak group under load. The existing observations include voltage sag under acceleration, rising temperature during sustained demand, and group differences that become clearer under load.

Bluetooth is not a substitute for safe observation. Do not watch a phone while riding or depend on a continuous connection for braking or other riding decisions. Use a suitable recording setup or assistance for controlled tests.

System Overview

Technical Fundamentals

Protection System

The BMS enforces:

• Overvoltage protection (OV)
• Undervoltage protection (UV)
• Overcurrent protection
• Temperature protection

A BMS protection event can disable battery output. The motor controller may separately reduce power under its own protection logic; a gradual reduction and a complete shutdown need different checks.

MOSFET Control

• Charge and discharge paths are controlled internally
• When a limit is exceeded, the BMS opens the circuit
• This results in instant loss of power to the system

This is why shutdowns feel abrupt rather than gradual.

Balancing

• Passive balancing only
• Removes energy from higher cells
• Active near full charge
• Cannot correct large imbalances

What the BMS Cannot See

The BMS only sees what is happening inside the battery.

It does not see:

• motor demand before it happens
• throttle input
• controller behavior

This is why shutdowns can feel sudden. The system demand happens first, and the BMS reacts after limits are exceeded.

80V 45Ah Systems (Typical 22S)

Focus:

• Managing higher voltage stress
• Avoiding false trips during regen
• Accounting for stronger sag under load

Current Behavior

The BMS rating does not reflect actual ONYX demand.

• Acceleration spikes exceed nominal current
• Controller demand is not limited by BMS rating
• The BMS only reacts after limits are exceeded

This is why the system can feel stable at low power but shut down instantly under heavy acceleration.

Recommendations:

• Match controller demand to the battery and complete current path
• Have repeated protection events diagnosed rather than changing the BMS limit
• Do not remove or bypass protection

Voltage Sag and Weak Cells

Most real-world shutdown issues come down to voltage sag.

What happens:

1. You apply throttle
2. Current demand increases
3. Voltage drops across the pack
4. One cell drops faster than the others under load
5. UV protection is triggered
6. The BMS cuts power

Key points:

• Pack voltage alone is misleading
• The lowest cell determines shutdown
• Sag must be evaluated under load, not at rest

This is the exact moment where most riders experience sudden power loss.

Recommendations:

• Watch cell voltages during acceleration
• Identify the lowest cell under load
• Have the configured protection checked against the pack specification; do not lower it to mask a fault

Voltage Sag Reference

Voltage sag is the drop between resting voltage and voltage under load. It happens instantly when throttle is applied, and the harder the acceleration, the larger the sag.

Large sag can contribute to a protection event; it is not the only possible cause of a shutdown.

These ranges are observations retained from the earlier guide, not manufacturer pass/fail specifications. Interpret them with load, temperature, charge level, and actual cell group measurements.

Cell Delta Under Load

The earlier guide uses these delta ranges as an interpretation aid. They are not a manufacturer fault-code table. Compare readings under controlled, consistent conditions and confirm sensing connections before diagnosing a failed group.

Balancing Behavior

Passive balancing has limits, but it is always active when conditions are met.

• Balancing is fully automatic on these systems
• No manual control is required
• The BMS handles it internally

Balancing only becomes effective near the top of the charge range under normal conditions.

• Typically begins around 80 percent charge and above
• Most active close to full charge
• Below that range, little to no balancing occurs

This means:

• The battery needs to be charged high enough for balancing to happen
• Letting the battery sit at a higher state of charge allows the system to correct small differences between cells

This is why partial charging over long periods can slowly increase imbalance.

The app is useful here:

• It shows state of charge
• It shows cell voltages
• It lets you confirm when balancing conditions are met

Practical behavior:

• Small imbalances often correct themselves over time
• Repeated full or near-full charges help maintain balance
• If the pack is slightly out of balance, letting it sit at high charge can improve it

Limitations:

• Balancing is slow
• Only active near the top of charge
• Cannot fix a degraded or failing cell

Warning:

If a group keeps deviating, investigate the cells and sensing connection instead of assuming more balancing will fix it.

Diagnostics

If you experience shutdown under acceleration:

1. Arrange a controlled test with suitable recording or assistance
2. Record cell voltages and battery behavior under the test load
3. Identify the lowest cell
4. Compare delta against other cells
5. Have the pack and sensing connections inspected before considering any configuration change
6. Repeat under consistent throttle conditions for accurate comparison

The goal is to reproduce the issue under controlled conditions, not guess based on idle readings.

Use the app for:

• Identifying weak cells
• Observing sag patterns
• Tracking imbalance over time
• Verifying protection events

The displayed state of charge is an estimate. Interpret it alongside voltage and behavior, especially under load.

Do not use the app for:

• Real-time riding decisions
• Accurate state of charge
• Absolute measurements without validation

Regenerative Behavior

Regenerative braking can trigger overvoltage protection.

• Occurs during downhill or aggressive deceleration
• More noticeable at higher pack voltages
• Can cause sudden cutoff if limits are too tight

Recommendations:

• Check charge level and whether the battery can accept regen
• Have repeated cutouts diagnosed before changing settings

Hardware and Thermal Considerations

ONYX battery compartments are enclosed.

Effects:

• Heat buildup under load
• Reduced efficiency of internal components
• Increased chance of thermal shutdown

Heat builds gradually, but shutdowns happen instantly.

Recommendations:

• Improve airflow where possible
• Do not raise temperature limits to compensate
• Treat thermal issues as system design problems

What the App Cannot Establish

App readings alone do not establish true usable capacity, internal resistance, hidden mechanical damage, or the condition of every connection. They can show symptoms without identifying the physical cause. Intermittent or brief changes can also be missed between Bluetooth updates.

A battery that looks normal at rest may still have a fault. For cutouts under acceleration, use battery-demand diagnosis when applicable to the installed controller. For implausible high and low readings that change with movement, the 41Ah balance-lead case illustrates a sensing fault; its repair details are specific to that battery.

Before Returning to Normal Use

Confirm the cause of a shutdown and verify stable readings and normal protection behavior after any repair. A cleared message or a reconnected app is not proof that the underlying problem is fixed. The battery’s protection limits are boundaries, not operating targets.