This post is a technical reference for the 72V ONYX 41Ah battery.
It focuses on real-world behavior, including charging strategy, BMS behavior, calibration, temperature limits, imbalance recovery, configuration states, and performance under load.
ONYX 41Ah 72V Battery Aging
The ONYX 41Ah battery pack has reached an age where reduced performance is expected. Riders will typically see shorter range, weaker acceleration, heavier voltage sag under load, and higher battery temperatures during aggressive riding, all caused by rising internal resistance in the cells.
Aging vs Damage
Aging is expected:
- increased voltage sag
- reduced range
- slower balancing
- higher operating temperatures
Damage is not expected:
- extreme cell delta
- dead or missing cell group readings
- pack only working when charger is connected
- unstable resting voltage
At this stage, the pack should not be pushed beyond stock Kelly controller limits. High-current modes such as SICKO MODE or FarDriver JAWS MODE can overstress aging cells, leading to rapid degradation and permanent capacity loss.
ONYX 41Ah 72V DC Current and Phase
- DC Current Amps: 80A to 90A
- DC Boost Current: 90A to 100A
- AC Phase Current: 180A to 240A
ONYX 41Ah 72V System Overview
| Component | Value |
|---|---|
| Nominal System | 72V |
| Cell Configuration | 20s |
| Cell Groups | 20 (series) |
| Cell Count | ~160-200 |
| Cell Type | 18650 / 21700 NMC |
| Full Voltage | 84V |
| Storage Voltage | ~74V |
| Empty Voltage | ~60V |
ONYX 41Ah 72V Real-World Range
Range varies significantly depending on terrain, rider weight, temperature, and riding style.
| Riding Condition | Expected Behavior |
|---|---|
| Flat terrain / city riding | higher range, more consistent discharge |
| Hilly terrain / steep grades | reduced range due to sustained load |
| Aggressive riding | reduced range and higher temperatures |
| Moderate riding | improved efficiency and lower sag |
Environmental factors such as wind, elevation, and stop-and-go riding also affect range.
ONYX 41Ah 72V Battery Management System (BMS)
The battery uses a BMS to:
- prevent over-current and short circuits
- monitor temperature
- balance cell groups
- track voltage, capacity, and health
The BMS controls balancing behavior, protections, calibration accuracy, and charge/discharge limits.
Observed vs Configured Behavior
- Configured behavior is defined by BMS settings
- Observed behavior reflects how the pack behaves in real-world conditions
Differences between these states can occur depending on configuration and battery condition.
ONYX 41Ah 72V BMS Apps
Use the Overkill Solar or Xiaoxiang apps to monitor and configure the battery.
ONYX 41Ah 72V What the Apps Show
- pack voltage
- cell group voltages (1-20)
- cell delta
- battery temperature
- State of Health (SOH)
- error history
Interpreting Key Values
- Cell delta
- ~0.005V optimal
- 0.005-0.040V healthy
- Temperature
- reflects internal resistance and load
- SOH
- estimate, not absolute
- Error logs
- indicate protection events
ONYX 41Ah 72V Charging Times
| Battery | Charger | 0 -> 100% | 50 -> 100% |
|---|---|---|---|
| 41Ah | 5A | 10.6 h | 7.6 h |
| 41Ah | 10A | 5.4 h | 3.6 h |
Additional charging time references:
5 Amp Charging To 97% (83.3 Volts)
- 0% To 97% - 9.2 Hours
- 50% To 97% - 3.6 Hours
10 Amp Charging To 97% (83.3 Volts)
- 0% To 97% - 4.6 Hours
- 50% To 97% - 1.8 Hours
ONYX 41Ah 72V Charging Behavior
Charging to 83-83.5V is faster and reduces long-term stress on the battery.
Charging from ~97% to 100% is constant-voltage charging, which is not the same as balancing.
- ~95 minutes from 97% to 100% with a 2A-8A charger
- current tapers while voltage remains constant
Balancing requires time at higher voltage, not just reaching full charge. Calibration and balancing improve consistency and readout accuracy, but they do not restore lost capacity or reverse cell aging.
ONYX 41Ah 72V Best Charging Practice
| Use Case | Voltage |
|---|---|
| Daily riding | 78-81 V |
| Long storage | ~74 V |
| Maximum range | 83-84 V |
ONYX 41Ah 72V Charge Cycle Multipliers
| Charge Level | Life |
|---|---|
| 84 V | 1× |
| 83 V | 1.5× |
| 82 V | 2× |
| 81 V | 3× |
| 80 V | 4× |
ONYX 41Ah 72V Temperature Guidelines
- discharge maximum: 140°F / 60°C
- charge recommended: 40°F-105°F (4°C-40.5°C)
- charge limits: 32°F-113°F (0°C-45°C)
- rest 30-60 minutes after riding
Additional behavior:
- BMS recovery: 135°F / 57.2°C
- above 120°F / 49°C -> reduce load
ONYX 41Ah 72V Safety Basics
- avoid charging in direct sunlight
- do not charge below 32°F (0°C) or above 113°F (45°C)
- clean XLR connectors periodically
- stop use if resting voltage becomes unstable
Cleaning Connectors
- use isopropyl alcohol or contact cleaner
- apply a small amount (1-2 drops)
- clean with cotton swab
- allow to dry before use
ONYX 41Ah 72V Fault Patterns
Cell Group Too High
- one cell group significantly higher than others
- commonly indicates balance wire or sensing issue
Cell Group Too Low
- one cell group significantly lower than others
- may indicate cell failure or disconnected balance lead
Slight Imbalance
- ~0.090V
- generally resolves with proper charging
Moderate Imbalance
- ~0.060V-0.300V
- requires monitoring or corrective action depending on trend
Severe Imbalance
- ~0.300V-0.500V or higher
- recovery may not be successful
Damaged Battery
- only powers on when charger is connected
- reports 0Ah or incorrect values
- discontinue use
ONYX 41Ah 72V Under Load Cell Test
- open BMS app
- view cell groups
- record screen
- apply throttle
Observe:
- one cell group dropping faster -> weak group
- uneven sag -> imbalance or degradation
Perform this test only when the bike is safe to operate and only long enough to capture the behavior.
ONYX 41Ah 72V BMS Variants
80A BMS
- charge overcurrent: 90000
- discharge overcurrent: 90000
100A BMS
- charge overcurrent: 110000
- discharge overcurrent: 110000
Higher current BMS units provide increased output but increase stress on aging cells.
Connector Limitation Note
- SB50 connectors limit maximum output
- upgraded connectors (e.g., OSE) reduce restriction
ONYX 41Ah 72V BMS Misconfiguration Fix
Incorrect settings can cause:
- inaccurate capacity readings
- early cutoff
- increased imbalance
Required Values
- Total Battery Capacity: 41000
- Total Cycle Capacity: 32800
Process
- connect within close range
- BMS Read -> modify -> BMS Write
- confirm settings before use
ONYX 41Ah 72V Voltage Sag
| Sag | Range |
|---|---|
| 3-8 V | lower |
| ~10 V | elevated |
| 10-15 V | high |
| 15 V+ | very high |
Sag varies depending on:
- state of charge
- temperature
- load
- battery age
High sag at lower voltage or under higher load is generally expected. The same battery can show very different sag behavior depending on conditions.
ONYX 41Ah 72V Common Mistakes
- charging immediately after aggressive riding
- not allowing time for balancing
- leaving recovery settings enabled
- using high current on aged packs
- ignoring temperature limits
ONYX 41Ah 72V Quick Workflow
- check pack voltage and cell delta
- check temperature
- verify BMS configuration
- attempt balancing
- evaluate after 3-10 days
Battery Diagnostics
For full diagnostic workflows:
Final Notes
The ONYX 41Ah battery requires attention to:
- current limits
- temperature
- balancing behavior
- calibration accuracy
- configuration states
Aging increases sag and heat. Balancing improves consistency, not capacity. Configuration mistakes can create false symptoms or early cutoffs. Maintaining low cell delta, proper charging practices, and correct BMS configuration will significantly extend usable life.
Detailed Guides