QS138 & QS165 Mid Motor Battery Selection Guide
QS138 & QS165 Mid Motor Battery Sizing Guide
Eliminate voltage sag, thermal cut-offs, and BMS trips. Match continuous DC discharge current and Smart BMS thresholds specifically for high-kW QS138 & QS165 mid-drive motor builds.
Controller & Battery Matching Reference
Fardriver ND72550
- Target MotorQS138 70H / QS165
- Required BMS180A Continuous
- Cell ChoiceSamsung 50S / 50G
- Cable Gauge8AWG Silicone
- Main ConnectorQS8 Anti-Spark
Fardriver ND72800
- Target MotorQS138 90H V2 / Heavy
- Required BMS220A Continuous
- Cell ChoiceSamsung 50S Extreme
- Cable Gauge6AWG Silicone
- Main ConnectorQS8 Anti-Spark
VESC 75300 / 84450
- Target MotorQS138 70H / High Speed
- Required BMS200A Smart BMS
- Cell ChoiceSamsung 50S (Bluetooth)
- Cable Gauge8AWG Silicone
- Main ConnectorQS8 / Anderson SB50
Sabvoton 72150 / 72200
- Target MotorQS138 70H V1 / Mild
- Required BMS150A - 180A Continuous
- Cell ChoiceSamsung 50G / 50S
- Cable Gauge8AWG Silicone
- Main ConnectorQS8 / XT90-S
QS Mid Motor Power Configuration Tiers
72V 30Ah / 40Ah (120A BMS)
Samsung 50G high-density cells. Ideal for QS138 70H motors running under 100A DC battery draw for street commuting.
72V 40Ah / 50Ah (180A BMS)
Samsung 50S high-discharge cells. Zero voltage sag under heavy throttle bursts on QS138 90H / QS165 trail setups.
72V 50Ah / 60Ah (220A BMS)
Heavy-duty steel armor casing with 220A continuous Smart BMS. Handles max phase current output without thermal throttling.
84V 40Ah / 50Ah (250A BMS)
Ultra high RPM top speed architecture. Compatible with VESC 84450 and Fardriver 84550 extreme race controllers.
Phase Current vs DC Battery Draw
High phase-current controllers draw intense DC battery current during rapid throttle acceleration:
- Fardriver ND72550 (550A Phase): Draws approx. 150A-180A DC current from battery. Requires at least 180A continuous BMS.
- Fardriver ND72800 (800A Phase): Draws up to 220A DC current. Pair with Samsung 50S cells to prevent cell thermal overload.
- VESC 75300 / 84450: Pair with Smart Bluetooth BMS for live temperature telemetry monitoring.
Connectors & Wiring Standards
High continuous current demands heavy-gauge silicone wire and anti-spark plugs:
- QS8 Anti-Spark Connector: Standard on BOOANT QS mid-motor packs (handles 180A+ continuous without terminal arc pitting).
- 8AWG High-Temp Wire: Ultra-flexible copper silicone cables for tight chassis routing.
- Smart BMS App: Real-time Bluetooth monitoring of cell voltages and BMS MOSFET temperatures.
Frequently Asked Questions
Q: What is the difference between DC current and Phase current?
A: Phase current is the AC current sent from the controller to the motor windings creating low-speed torque. DC current is the actual current drawn from the battery. A controller outputting 500A phase current may only draw 150A-180A DC current from the pack.
Q: Why is Samsung 50S recommended for QS138 90H builds?
A: QS138 90H mid motors deliver huge torque under heavy load. Samsung 50S cells support up to 25A-35A continuous discharge per cell, maintaining stable voltage without excessive thermal buildup.
Q: Can I request custom battery dimensions for my swingarm frame?
A: Yes! Most QS138 builds use custom-built frames or converted dirt bike chassis. Measure your clear internal space and submit your dimensions via our Custom Battery Form.
