ONYX Connectors (Charge vs Discharge, Limits)

This page is part of the ONYX Battery Guide

The ONYX 72V platform uses separate connector systems for charging and high-current discharge, each with different electrical limits, wiring constraints, and failure points.

• XLR, XT60, and XT90 are used for battery charging
• QS8 and SB50 are used for high-current battery discharge

This post covers connector types, pin configuration, wire limits, routing options, discharge port charging behavior, and battery lead performance.

These connectors are used on the following ONYX battery configurations:

• ONYX 72V 45Ah
• ONYX 72V 41Ah
• ONYX 72V 23Ah

The ONYX 80V 45Ah battery and ONYX CTY2 23Ah do not use an XLR charge connector.

Connector performance depends on both electrical and environmental factors:

• Routing impacts durability and accessibility
• Pin alignment is direct between mating connectors
• Environmental exposure is the primary failure cause
• Regular cleaning reduces resistance and charging issues

System Overview

XLR Charging Connector (72V)

• 72V - XLR Battery Connector Female
• 72V - XLR Charger Connector Male

The ONYX 72V charging system uses a 3-pin XLR connector with two active pins for DC charging.

• Battery: female XLR
• Charger: male XLR
• Alignment: direct (1:1, no crossover)

Pin Configuration (Battery & Charger)

• Pin 1: Positive (+)
• Pin 2: Negative (-)
• Pin 3: Not Used

Pins align directly when mating the connectors.

Charger Wire Colors (Stock ONYX 72V 10 Amp)

XLR Connector Amps

Video - How To Solder a XLR Connector

XLR Connector Routing Options

• 72V - XLR Extension Cable

There are multiple ways to position and access the battery’s XLR connector.

• Option 1: Leave inside and slide cover back
• Option 2: Use an XLR extension cable
• Option 3: Route through right-side hole externally

If routing externally, periodically check that the connector is clean and free of dirt or debris. A 3D-printed external dust cap helps keep it protected.

Charge Port Connector Wire

From 2018 to 2021, the stock ONYX RCR 23Ah battery came with a 16 AWG charge port wire, a specification that continued with the ONYX 41Ah battery from 2021 to 2024 and remains unchanged in the ONYX 45Ah battery as of 2025.

XLR Charge Connector

Stock XLR connectors exist in two main variants:

• Blue XLR: supports up to 13A
• Black XLR: limit to 10A

Upgrades:

• Replace black XLR with Neutrik connectors
• Upgrade to XT60 or XT90 for improved connection quality

XT Charge Connectors

• XT60 Charge Connector / Male and Female
• XT90 Charge Connector / Male and Female

XT60 and XT90 connectors provide improved efficiency, size, and environmental resistance compared to XLR.

• Connect at an angle so positive (+) engages first

XT60 Charge Connector Specifications

• Dimension: 16mm x 8mm x 19mm
• Maximum Wire Size: 12 AWG
• Compatible Wire Sizes: 10 AWG to 14 AWG
• Temperature Range: -20°F to +250°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Continuous Current: 60A
• Peak Current: 80A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

XT60 Variations

XT90 Charge Connector Specifications

• Dimension: 21mm x 13mm x 29mm
• Maximum Wire Size: 8 AWG
• Compatible Wire Sizes: 8 AWG to 12 AWG
• Temperature Range: -20°F to +250°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Continuous Current: 90A
• Peak Current: 120A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

XT90 Variations

XLR to XT60 Charge Adapter

• Female XLR to Male XT60 Adapter

Always follow the lowest-rated component in the chain.

• XLR limit: 10A

Charging Efficiency

An 84V charger draws approximately 11.67A from a 120V AC outlet when outputting 15A at 84V DC with 90% efficiency.

• Voltage drop >6V (5%) can reduce outlet voltage below 114V
• This may cause breaker trips on a 15A circuit

An 84V charger can output approximately 19.3A DC before exceeding a 15A AC breaker, assuming:

• 90% efficiency
• Dedicated circuit
• Proper wiring for distance

Discharge Port Charging

All ONYX batteries since 2018 support charging through the discharge port.

• Requires charger connector modification to SB50 or QS8
• Functions similarly to regenerative braking current flow

Charging behavior:

• 15A–20A is acceptable for larger batteries
• Higher sustained amperage reduces cycle life

Discharge Port BMS Charging Cap

ONYX batteries are limited by their BMS in terms of the maximum amperage they can be charged from the discharge port.

Adapter Warning

• Do not convert XLR / XT60 / XT90 to SB50 or QS8 using adapters

XLR Failure

Exposure to water, dirt, or salt can damage XLR connectors and prevent charging.

• Corrosion on pins or sockets
• Increased resistance
• Intermittent charging
• Complete failure

Cleaning XLR Charge Connector

Tools & Materials

• Isopropyl alcohol (90%+)
• Lint-free swabs
• Compressed air (optional)
• Soft brush (optional)
• Contact cleaner (DeoxIT D5)
• Plastic pick (optional)

Male Connector

• Inspect pins
• Clean with alcohol
• Rotate swab around pins
• Blow debris out
• Apply contact cleaner
• Dry completely

Female Connector

• Inspect socket holes
• Clean using wrapped swab or pick
• Rotate gently
• Remove debris
• Apply cleaner
• Dry and blow out

Extra Tips

• Avoid metal tools
• Do not oversaturate
• Replace severely corroded connectors

Video - How To Properly Clean an XLR Connector

Discharge Connectors 72V

High-current connectors transfer power between battery and controller.

• Higher current than XLR
• Sensitive to installation quality

Battery leads affect:

• Heat
• Voltage drop
• Durability
• Current delivery

QS8 Connector (Soldered – 6 AWG)

Overview

• Anti-spark connector
• High current design
• Uses 6 AWG stranded copper

Tools & Materials

• High wattage iron
• Solder
• Heat shrink
• Flux (optional)
• Clamp

Wire Preparation

• Strip cleanly
• Twist strands
• Optional pre-tin

Soldering Process

• Pre-heat cup
• Add solder
• Insert wire
• Heat until flow
• Fully fill cup

Inspection

• Smooth joint
• No exposed strands
• No movement

Important Notes

• Install heat shrink first
• 6 AWG requires high heat
• Avoid cold joints

Video - How To Solder a QS8 Connector

SB50 Connector Crimp 8 AWG

Overview

• Anderson connector
• Modular design
• Uses 8 AWG wire

Tools & Materials

• Proper crimper
• Contacts
• Housing

Wire Preparation

• Strip clean
• Do not tin

Crimping Process

• Insert wire
• Use correct die
• Perform single crimp

Inspection

• Pull test
• No loose strands
• Proper deformation

Housing Installation

• Insert until click
• Verify orientation
• Confirm lock

Important Notes

• Do not solder
• Poor crimps increase heat

Video - How To Crimp a SB50 Connector

Connector Scaling Overview

Battery Lead Upgrade

• Purchase QS8 Battery Lead

Controller upgrades require QS8 6 AWG 14" leads.

Battery Lead Comparison

Battery Lead ONYX RCR LTD

Comes stock with QS8 6 AWG 14".

QS Connector Burnout and Thermal Behavior

The QS8, QS9, QS10, and QS12 connectors’ 5 ohm resistance is insufficient for anti-spark control at higher voltages.

• Causes inrush “snap”
• Leads to connector erosion

Inrush Mitigation

• Connect at an angle (positive first)
• Use 15 mΩ pre-charge resistor

Thermal Behavior

• 150°F is normal
• Heat increases resistance
• Reduces efficiency

Heat spreads to:

• Terminals
• Controller leads
• BMS
• Enclosure

Thermal Monitoring

Use a thermal camera:

• Battery leads
• Battery
• Controller
• Motor

High-Load Testing Warning

Pushing battery lead wires to their limits is an art—one with complex processes that can’t be ignored. You’re riding the edge of setting the wire on fire without actually lighting it up.

• Take detailed notes during testing
• Perform testing in winter when possible
• Account for higher summer temperatures

Battery Lead Length

Wire length affects resistance, heat, and performance.

• Shorter = lower resistance
• Material and construction matter

Recommended:

• Silicone OFC wire
• Electrical joint compound
• Proper soldering and crimping
• PET sleeving

Battery Lead Amp Limits

Wire Limits

Battery Lead Bigger Configurations

Battery Lead Ratings

Dual Battery Leads

Dual leads depend on battery capability.

Dual Battery Lead Rating

QS8 Discharge Connector

QS8 connectors are commonly used with 6 AWG wires and are a compact high-current alternative to the stock SB50 connector.

Specifications

• Maximum Wire Size: 6 AWG
• Compatible Wire Sizes: 8 AWG to 10 AWG
• Temperature Range: -20°F to +300°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Peak Current: 180A
• Continuous Current: 110A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

QS9 Discharge Connector

The QS9 connector is available in multiple configurations. The variation best suited for an ONYX is the QS9-L.

Specifications

• Maximum Wire Size: 6 AWG
• Compatible Wire Sizes: 4 AWG to 6 AWG
• Temperature Range: -20°F to +300°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Peak Current: 220A
• Continuous Current: 160A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

QS10 Discharge Connector

The compact QS10 variation without the center bus pins that best suits an ONYX is the QSP10P-L.

Specifications

• Maximum Wire Size: 4 AWG
• Compatible Wire Sizes: 4 AWG to 6 AWG
• Temperature Range: -20°F to +300°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Peak Current: 270A
• Continuous Current: 210A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

QS12 Discharge Connector

The QS12-M is the variation best suited for high-current ONYX builds.

Specifications

• Maximum Wire Size: 4 AWG
• Compatible Wire Sizes: 3 AWG to 4 AWG
• Temperature Range: -20°F to +300°F
• Metal Material: Pure Gold-Plated Brass
• Plastic Material: Nylon Reinforced with Fiber
• Flame Retardant Rating: UL94 V0
• Rated Voltage: DC 500V
• Peak Current: 320A
• Continuous Current: 250A
• Resistance: 5 ohm
• Recommended Usage: Up to 1,000 cycles

Final Advice

Connector reliability depends on installation, cleanliness, and system limits.

• XLR requires regular cleaning and protection
• XT improves charging durability
• QS8 depends on proper soldering
• SB50 depends on correct crimping
• Respect BMS charging limits
• Poor connections increase resistance and heat
• XLR is for charging only