iRhapsody 12V DC SPST Automotive Relay Kit, Pack of 6 — 40A Contacts, Harnessed

The iRhapsody 4-pin 12V DC relay kit is a set of six SPST automotive relays with harnesses engineered to switch up to 40A at 14V and handle a wide range of automotive control tasks.

This kit supplies six identical 12V relays and matching wiring harnesses so you can quickly replace worn relays or build new circuits for lights, fans, pumps, or accessory power. Each relay uses a nominal 12 VDC coil with 1.8 W coil power and 80 Ω resistance, and the parts are specified for long operational life and robust electrical isolation. The pack is intended for hobbyists, mechanics, and installers who need reliable switching components rated for typical vehicle environments.

How reliable are these relays for frequent switching?

The relays are rated for extensive electrical and mechanical cycles to suit repeated on/off use. Electrical life is specified at 100,000 operations under rated switching conditions; mechanically the relay is designed for up to 10 million cycles, showing the device can tolerate many actuations before wear becomes a concern.

• Electrical life: 100,000 operations (at 30 operations/minute)
• Mechanical life: 10,000,000 operations
• Operate time ≈ 7 ms; release time ≈ 5 ms for responsive switching

What electrical load and environment can these relays handle?

Each relay is a single pole single throw (SPST) normally open contact rated for 40A at 14V DC, allowing switching of high-current accessories within the stated limits. The dielectric and insulation figures indicate good separation between coil and contacts, and the part is specified to function across common automotive temperature and humidity ranges.

• Contact rating: NO 40A at 14V DC; max switching power 560 W
• Temperature range: -30°C to +80°C; humidity tolerance 40%–85%
• Dielectric strength: 500 VAC between open contacts; 750 VAC between contact and coil

How should I size these relays in my electrical projects?

Choose these relays for circuits where the continuous current and inrush demands remain reasonably below the 40A contact rating, and aim to leave a safety margin to extend relay life. The kit’s harnesses and wire gauges are selected for high-current paths and coil control leads; keep wiring lengths and terminal quality in mind to reduce voltage drop and heating.

• Recommended practice: operate 10–15% below maximum rated current for longevity
• Primary harness leads use 12 AWG tinned copper suitable for high-current loads
• Coil leads use 16 AWG for reliable control signal delivery

What are the control voltages and switching characteristics?

The relays are designed around a 12 VDC coil with defined operate and release thresholds that fit typical vehicle electrical systems. They will actuate and release quickly, and their coil and contact resistances are specified to help you design predictable control circuits and fuses.

• Nominal coil voltage: 12 VDC; coil power: 1.8 W; coil resistance: 80 Ω
• Must operate voltage: 6–8 VDC; must release voltage: 0.6–3.6 VDC
• Maximum applied coil voltage: 15.6 VDC; contact resistance ≤100 mΩ (at 6 VDC, 1 A)

Who this is for: installers, DIY mechanics, vintage car restorers, and electronics builders who need multiple matched relays with harnesses for powering lights, electric fans, pumps, auxiliary batteries, or aftermarket accessories. This pack gives you six ready-to-use relays so you can standardize replacements or outfit several circuits at once without sourcing individual parts.