JST RCY Connector (JST SYP): Complete Guide to 2-Pin Wire-to-Wire Specs, Part Numbers & Adapter Compatibility
Search for "JST RCY connector" and you’ll find product listings, a few forum threads, and almost no engineering documentation. Search for "JST SYP" and you’ll find the same products under a different name. This is the first problem the JST RCY creates for engineers and hobbyists: it has two names. The JST official designation is RCY. The market name — used by most distributors, RC hobbyists, and electronics suppliers — is SYP. They are the same connector.
Beyond the naming confusion, the RCY is a deceptively capable connector: a 2.5mm pitch, 2-pin wire-to-wire crimp connector with a free spring socket contact that provides reliable mating without a positive latch, rated for 3A at 250V AC/DC, available in red (standard) and white (UL Listed), and used extensively in RC battery packs, servo leads, sensor wiring, and small actuator connections. This guide covers everything: the SYP vs RCY naming question, complete electrical specifications, all housing and terminal part numbers, UL Listed variants, and a full adapter compatibility guide for XT30, JST PH, Tamiya, and Ultra Micro connectors.
JST RCY vs JST SYP: The Naming Question Answered
This is the most-searched question about this connector and the least-answered one online. Here is the definitive answer:
JST RCY and JST SYP are the same connector.
- RCY is the official JST series designation, as listed in the JST catalog and datasheet. The full system uses housing part numbers SYR-02T (receptacle) and SYP-02T-1 (plug), and terminal part numbers SYM-001T-P0.6 (pin) and SYF-001T-P0.6 (socket).
- SYP is the market name derived from the plug housing part number prefix (SYP). It became the dominant name in the RC hobby, robotics, and electronics communities because distributors and resellers labeled their products after the plug housing.
- JST-RCY (with hyphen) is a common variant spelling used in datasheets and technical documents — same connector.
When you see products labeled "JST SYP 2P", "JST-RCY connector", "JST RCY 2-pin", or "SYP-02T-1" — they all refer to the same 2.5mm pitch, 2-pin wire-to-wire connector from JST’s RCY series.
Why does this matter? If you search for replacement parts using the wrong name, you may not find the correct mating connector. Always cross-reference: SYR-02T mates with SYP-02T-1. SYM-001T-P0.6 (pin) goes into SYR-02T. SYF-001T-P0.6 (socket) goes into SYP-02T-1.
What Is the JST RCY Connector? Key Features
The JST RCY series is a 2.5mm pitch, 2-pin wire-to-wire crimp connector designed for small-current, compact wiring applications. Three features define it:
1. Wire-to-wire only, 2-pin only
The RCY is a dedicated wire-to-wire system — no PCB header exists or is available. The SYR receptacle and SYP plug connect two wire harnesses directly. The connector is available in 2-pin only — there are no 3P, 4P, or higher circuit count variants in the RCY series. For multi-pin wire-to-wire applications, see the JST SM series (2–18P).
2. Free spring socket contact
The SYF-001T-P0.6 socket contact uses a free spring structure — the contact spring is not constrained by the housing wall during mating. This provides consistent contact force across the mating cycle and allows the connector to mate and unmate without a positive latch mechanism. The result is a connector that is easy to disconnect by hand but maintains reliable electrical contact under normal operating conditions.
3. Red housing as standard, white for UL Listed applications
Standard RCY housings (SYR-02T, SYP-02T-1) are red — making them visually distinctive in multi-connector assemblies. The UL Listed variants (SYR-02TV, SYP-02TV-1) are white (natural). Both are electrically and mechanically identical; the color difference reflects the UL recognition status of the housing material.
➡️ Browse all JST RCY/SYP assemblies: JST SYP 2.5mm Cable Assemblies and Connector Kits at Keszoox
JST RCY Electrical Specifications
| Parameter | Specification |
|---|---|
| Pitch | 2.5mm |
| Connector type | Wire-to-wire crimp (disconnectable) |
| Circuit count | 2 only |
| Current rating | 3A AC/DC max. |
| Voltage rating | 250V AC/DC |
| Temperature range | -25°C to +85°C (including temperature rise under rated current) |
| Contact resistance (initial) | 10mΩ max. |
| Contact resistance (after environmental test) | 20mΩ max. |
| Insulation resistance | 500MΩ min. |
| Withstanding voltage | 1,500V AC for 1 minute |
| Applicable wire gauge | AWG #28 to AWG #22 |
| Conductor cross-section | 0.08 to 0.33 mm² |
| Insulation O.D. | 1.0mm to 1.7mm |
| Contact structure | Free spring (socket contact) |
| Locking mechanism | None (friction fit, free spring contact) |
| Housing material | PA 66, red (standard) / natural white (UL Listed TV variant) |
| Contact material | Phosphor bronze, tin-plated (LF/SN — lead-free) |
| UL recognition | E60389 (TV variants only) |
| RoHS compliance | Yes (RoHS2) |
Important note on current rating and amp limit: The JST RCY is rated at 3A per contact at 250V AC/DC. In RC battery applications at 1S LiPo voltages (3.7V–4.2V), the 3A rating is the limiting factor — do not exceed 3A continuous through an RCY connector regardless of the battery’s discharge rating. For higher-current RC battery applications, use XT30 (30A) or XT60 (60A) connectors instead.
Note on withstanding voltage: At 1,500V AC/minute, the RCY matches the JST SM and XH series — significantly higher than the JST EH (800V) and JST SCN (800V). The RCY’s high withstanding voltage relative to its compact size makes it suitable for low-current applications in higher-voltage systems.
JST RCY Housing Part Numbers
The RCY system uses two housing types: the SYR receptacle (pin contacts) and the SYP plug (socket contacts). Both are available in standard red and UL Listed white variants.
| Part Number | Type | Color | UL Listed | Circuits | Qty/Bag |
|---|---|---|---|---|---|
| SYR-02T | Receptacle housing | Red | No | 2 | 1,000 |
| SYR-02TV | Receptacle housing | Natural (white) | Yes (E60389) | 2 | 1,000 |
| SYP-02T-1 | Plug housing | Red | No | 2 | 1,000 |
| SYP-02TV-1 | Plug housing | Natural (white) | Yes (E60389) | 2 | 1,000 |
Standard (red) vs UL Listed (white) — how to choose:
- SYR-02T / SYP-02T-1 (red): Use for general applications, RC hobby, robotics, and consumer electronics where UL recognition of the housing is not required. Red color provides visual identification in multi-connector assemblies.
- SYR-02TV / SYP-02TV-1 (white): Use when UL Listed housing material is required by the end product’s certification requirements. Electrically and mechanically identical to the red variants. UL file E60389.
Mating rule: SYR receptacle mates with SYP plug only. Do not mix red and white housings in a UL certified assembly — mixing UL Listed and non-UL Listed housings may invalidate the UL certification.
JST RCY Crimp Terminals
The RCY series uses two crimp terminals — a pin contact (SYM) for the SYR receptacle and a free spring socket contact (SYF) for the SYP plug.
| Part Number | Type | Housing | Wire Gauge (AWG) | Conductor (mm²) | Insulation O.D. (mm) | Material | Qty/Reel |
|---|---|---|---|---|---|---|---|
| SYM-001T-P0.6 | Pin contact | SYR receptacle | #28 to #22 | 0.08–0.33 | 1.0–1.7 | Phosphor bronze, Sn-plated (LF) | 10,000 |
| SYF-001T-P0.6 | Free spring socket contact | SYP plug | #28 to #22 | 0.08–0.33 | 1.0–1.7 | Phosphor bronze, Sn-plated (LF) | 10,000 |
Terminal identification: SYM pin contacts go into the SYR receptacle. SYF free spring socket contacts go into the SYP plug. Both terminals are lead-free tin-plated (LF/SN). Do not substitute SYM-001T-P0.6 from the JST SM series — while the part number prefix is similar, the SM and RCY terminals are not interchangeable.
Crimping equipment:
- SYM-001T-P0.6 (pin): AP-K2N crimping machine, MKS-L dies, MK/SYM-001-06 applicator
- SYF-001T-P0.6 (socket): AP-K2N crimping machine, MKS-L dies, MK/SYF-001-06 applicator
Wire gauge selection: AWG #28 to #22 covers the full RCY terminal range. For RC battery applications, AWG #22 (0.33mm²) is the most common choice — it provides the lowest resistance at the 3A rated current. For sensor or signal wiring where current is low, AWG #26 or #28 is acceptable and reduces harness weight.
➡️ Need pre-crimped assemblies? JST SYP 2.5mm Pre-Crimped Terminal Cable 22AWG UL1007 PVC | JST SYP 2.5mm Pre-Crimped Silicone Cable 22AWG UL3239 (200°C, 3KV)
JST RCY Adapter Compatibility Guide
The most-searched questions about the JST RCY involve adapter compatibility — converting between RCY and other battery or connector standards. This section answers every common conversion question.
JST RCY to JST PH (JST-PH 2.0mm)
The JST PH is a 2.0mm pitch connector commonly used in small LiPo batteries (1S, 2S) in RC micro aircraft, drones, and portable electronics. The RCY (2.5mm pitch) and PH (2.0mm pitch) are not directly compatible — an adapter cable is required. The adapter connects a SYP-02T-1 plug on the RCY side to a PHR-2 housing on the PH side. Search terms: jst rcy to jst ph adapter, jst-ph 3 pin plug to jst-rcy socket power adapter lead, jst rcy to ph.
JST RCY to XT30
The XT30 is a 30A-rated gold-plated bullet connector used in higher-power RC applications (brushless motors, 2S–4S LiPo). Converting from RCY to XT30 requires an adapter cable — and a critical warning: the RCY is rated at 3A maximum. Do not use an RCY-to-XT30 adapter to charge or discharge batteries at currents above 3A through the RCY connector. The adapter is only appropriate for low-current signal or auxiliary connections. Search terms: jst rcy to xt30.
JST RCY to Ultra Micro Battery Connector
Ultra Micro connectors (used in Blade Helis, UMX aircraft, and similar micro RC platforms) are proprietary connectors rated for very low currents (typically 1–2A). An RCY-to-Ultra Micro adapter allows charging a micro battery pack through an RCY-equipped charger. Verify the current rating of the Ultra Micro connector before use — do not exceed its rated current even if the RCY can handle 3A. Search terms: jst rcy to ultra micro battery adapter.
JST RCY to Small Tamiya
Small Tamiya connectors are used in many entry-level RC cars and aircraft. An RCY-to-Small Tamiya adapter allows cross-compatibility between these ecosystems. Small Tamiya connectors are typically rated for 10–15A — the RCY’s 3A limit is the binding constraint in any such adapter. Search terms: jst rcy to small tamiya.
JST RCY to PCB (Wire-to-Board)
The RCY has no native PCB header — it is a wire-to-wire connector only. To connect an RCY wire harness to a PCB, options include: (1) terminate the wire leads directly to PCB pads, (2) use a 2.5mm pitch PCB header (such as a JST XH 2P header) with an adapter cable, or (3) use a through-hole SYM pin contact soldered directly to the PCB. Search terms: jst rcy pcb, jst rcy to pcb.
JST RCY to JST DS (Micro Losi)
The JST DS (also called Micro Losi or 1.25mm Micro JST) is used in very small 1S LiPo batteries. An RCY-to-DS adapter is used in micro RC applications. The DS connector is rated for approximately 2A — the DS connector’s rating, not the RCY’s 3A, is the limiting factor. Search terms: jst-ds jst-rcy adapter, jst-ds to jst-rcy adapter.
JST RCY vs JST SYP: Full Comparison
| Attribute | JST RCY | JST SYP |
|---|---|---|
| Official JST series name | RCY | Not an official JST series name |
| Market/common name | SYP (derived from plug housing prefix) | SYP |
| Housing part numbers | SYR-02T / SYP-02T-1 | Same — SYR-02T / SYP-02T-1 |
| Terminal part numbers | SYM-001T-P0.6 / SYF-001T-P0.6 | Same |
| Pitch | 2.5mm | 2.5mm |
| Circuits | 2 only | 2 only |
| Current rating | 3A | 3A |
| Are they the same? | Yes. JST RCY = JST SYP. Same connector, two names. | |
JST RCY vs JST SM: Wire-to-Wire Connector Comparison
| Feature | JST RCY (SYP) | JST SM |
|---|---|---|
| Pitch | 2.5mm | 2.5mm |
| Connection type | Wire-to-wire | Wire-to-wire |
| Current rating | 3A | 3A (2–12P) / 2A (18P) |
| Voltage rating | 250V AC/DC | 250V AC/DC |
| Withstanding voltage | 1,500V AC/min | 1,500V AC/min |
| Circuit count | 2 only | 2 to 18 |
| Locking mechanism | None (free spring) | Arm lock (positive latch) |
| Panel mount | No | Yes (0.5–2.0mm) |
| Housing colors | Red / White (UL) | Black / White |
| Contact structure | Free spring socket | Standard crimp contact |
| UL recognition | E60389 (TV variants) | E60389 |
| Best for | RC batteries, sensors, 2-wire actuators, micro electronics | Wire harness, panel enclosures, multi-pin, vibration-prone |
Choose RCY when: 2-pin wire-to-wire connection, easy hand-disconnect without a latch, RC battery or sensor application, compact form factor required.
Choose SM when: more than 2 circuits needed, positive arm lock required, panel mounting needed, vibration-prone environment.
➡️ JST SM Wire-to-Wire Complete Guide →
JST RCY in the JST Connector Ecosystem
| Series | Type | Pitch | Circuits | Lock | Best For |
|---|---|---|---|---|---|
| JST RCY (SYP) | Wire-to-wire | 2.5mm | 2 only | None (free spring) | RC batteries, sensors, 2-wire micro applications |
| JST SM | Wire-to-wire | 2.5mm | 2–18 | Arm lock | Wire harness, panel mount, multi-pin |
| JST XH | Wire-to-board | 2.5mm | 2–16 | None | PCB connections, Arduino, 3D printers |
| JST PH | Wire-to-board | 2.0mm | 2–16 | None | Small LiPo batteries, compact PCB |
| JST SH | Wire-to-board | 1.0mm | 2–15 | None | Ultra-compact, wearables, drones |
➡️ Common JST Connector Types & Applications → | Wire-to-Board Connector Types Guide →
How to Select the Right JST RCY / SYP Connector
- Confirm 2-pin requirement — The RCY is 2-pin only. For 3 or more circuits, use JST SM (wire-to-wire) or JST XH (wire-to-board).
- Verify current requirement — 3A maximum continuous. For RC applications above 3A, use XT30 (30A) or XT60 (60A) instead.
- Choose housing color — Red (SYR-02T / SYP-02T-1) for general use. White (SYR-02TV / SYP-02TV-1) when UL Listed housing is required.
- Select terminals — SYM-001T-P0.6 (pin) for SYR receptacle. SYF-001T-P0.6 (free spring socket) for SYP plug. Both cover AWG #28–#22.
- Choose wire type — Standard PVC (UL1007, 80°C) for general use. Silicone (UL3239, 200°C, 3KV) for high-temperature or high-flex RC and motor wiring.
- Confirm locking requirement — The RCY has no positive latch. If vibration resistance or accidental disconnection prevention is required, use JST SM (arm lock) instead.
➡️ Shop JST RCY / SYP assemblies: JST SYP Connector Kit with 22AWG Pre-Crimped Cables | JST SYP 2-Pin Male-Female Extension Cable 22AWG UL1007 | JST SYP 2-Pin Female Single-Head Cable 22AWG UL1007 | JST SYP 2-Pin Male Single-Head Cable 22AWG UL1007
➡️ Silicone wire options: JST SYP 2.5mm Silicone Cable 22AWG UL3239 (200°C, 3KV) | JST SYP Male Single-Head Silicone Cable 22AWG UL3239 | JST SYP Female Single-Head Silicone Cable 22AWG UL3239
Common Applications
- RC battery packs (1S LiPo) — The RCY/SYP is the standard connector for 1S LiPo batteries in micro RC aircraft, helicopters, and ground vehicles. The red housing provides visual identification; the free spring contact allows easy battery swapping without a latch.
- RC servo leads — Used as the connector on servo extension leads and Y-harnesses in RC systems where a simple 2-wire connection is needed.
- Sensor wiring — 2-wire sensors (temperature, pressure, proximity) in consumer electronics and industrial equipment where a compact, easy-disconnect wire-to-wire connection is required.
- Small actuators — Solenoids, micro motors, and small linear actuators operating within the 3A/250V rating.
- Robotics and maker projects — Power distribution in small robots, drones, and maker platforms where the 2-pin, easy-disconnect format is convenient for modular assembly.
- UL Listed applications (TV variants) — Consumer electronics and appliances requiring UL Listed connector components use SYR-02TV / SYP-02TV-1 white housings under UL file E60389.
Frequently Asked Questions
What is the JST RCY connector?
The JST RCY is a 2.5mm pitch, 2-pin wire-to-wire crimp connector rated for 3A AC/DC at 250V, operating from -25°C to +85°C. It uses a free spring socket contact (SYF-001T-P0.6) in the SYP plug housing and a pin contact (SYM-001T-P0.6) in the SYR receptacle housing. Available in red (standard) and white (UL Listed, E60389). Also known as JST SYP. ➡️ Shop JST RCY/SYP at Keszoox
Is JST RCY the same as JST SYP?
Yes. JST RCY and JST SYP are the same connector. RCY is the official JST series designation. SYP is the market name derived from the plug housing part number prefix (SYP-02T-1). They share identical housing part numbers (SYR-02T, SYP-02T-1), terminal part numbers (SYM-001T-P0.6, SYF-001T-P0.6), and electrical specifications.
What is the amp limit of the JST RCY connector?
The JST RCY is rated at 3A AC/DC maximum per contact. Do not exceed 3A continuous regardless of the battery’s discharge rating. For RC applications requiring more than 3A, use XT30 (30A rated) or XT60 (60A rated) connectors instead.
What is the JST RCY to JST PH adapter?
An RCY-to-PH adapter cable connects a JST RCY (2.5mm pitch) connector to a JST PH (2.0mm pitch) connector. These two connectors are not directly compatible due to different pitches and housing geometries. An adapter cable with SYP-02T-1 on one end and PHR-2 on the other is required. ➡️ Browse JST SYP/RCY cables at Keszoox
Can I use JST RCY for RC batteries?
Yes — the JST RCY/SYP is the standard connector for 1S LiPo batteries in micro RC applications. The 3A rating is sufficient for most 1S micro battery discharge rates. For higher-current 1S or multi-cell applications, upgrade to XT30 or XT60. The red housing makes battery polarity identification easy; always verify polarity before connecting.
What terminals does the JST RCY use?
SYM-001T-P0.6 (pin contact, for SYR receptacle) and SYF-001T-P0.6 (free spring socket contact, for SYP plug). Both cover AWG #28–#22 (0.08–0.33mm²), insulation O.D. 1.0–1.7mm. Lead-free tin-plated (LF/SN). Do not substitute SM series terminals — they are not interchangeable despite similar part number prefixes.
What is the difference between SYR-02T and SYR-02TV?
SYR-02T is the standard red receptacle housing. SYR-02TV is the UL Listed white (natural) receptacle housing, recognized under UL file E60389. Both are electrically and mechanically identical. Use the TV variant when UL Listed housing material is required by your product’s certification. The same distinction applies to SYP-02T-1 (red plug) vs SYP-02TV-1 (white plug, UL Listed).
How do I crimp JST RCY connectors?
Use the AP-K2N crimping machine with MKS-L dies. SYM-001T-P0.6 pin contacts go into the SYR receptacle; SYF-001T-P0.6 free spring socket contacts go into the SYP plug. Strip 3.0–3.5mm of insulation, crimp conductor and insulation wings, insert the terminal until the lance clicks, then mate SYP plug to SYR receptacle. ➡️ Shop pre-crimped JST SYP cables to skip the crimping step
➡️ JST SM Wire-to-Wire Guide → | JST XH Guide → | JST Connector Types → | Wire-to-Board Types → | Shop JST RCY/SYP →