What is the difference between an SPST and an SPDT automotive relay?

An SPST automotive relay has four pins and acts as a simple on-off switch across one circuit. An SPDT automotive relay uses five pins to route power between two circuits, providing one normally open and one normally closed output.

What current ratings are available for automotive switching?

Compel stocks relays rated across various capacities, including 30A, 35A, 40A, and 80A. For heavy equipment and high-current starter circuits, we offer units handling 100A / 200A.

Can I use an adjustable 2-pin relay for LED blinker conversions?

Yes, models like the Z-0269 2-Pin relay operate on 12V DC and support turn signals rated at 21W x 2 + 3.4W. They provide an adjustable flash frequency between 50 to 200 cycles/min for motorcycles and scooters.

When should I install a waterproof relay harness instead of an unsealed socket?

Install waterproof harness kits whenever the relay sits in an engine bay, along a commercial truck chassis, or in marine environments. Sealed waterproof housings stop road spray and washdown moisture from oxidizing the copper terminals.

Automotive Relays

1 product available

Sourcing a dependable 12v relay keeps commercial vehicle fleets, plant machinery, and powersports equipment running without electrical failure. Compel supplies automotive relays built for switching high-draw DC circuits under tough operating conditions. Our inventory serves auto electricians, fleet mechanics, and industrial equipment builders who require consistent contact performance in demanding transport environments.

The lineup spans standard switching components and specialized automotive relay designs, including flasher units and timer relay options. We supply loose switching units as well as complete pre-wired harness sockets with copper terminals. Order from Compel for fast trade fulfillment, verified technical specifications, and bulk volume supply.

1 products in Automotive Relays

Waterproof Automotive Relay 12V 24V 40A with harness and socket, featuring durable black housing and red copper terminals for reliable electrical switching.

Automotive Relays

40A Automotive Relay Kit | 12V/24V Waterproof 4-Pin & 5-Pin | Durable Socket with Harness

TBS-00569MAIN-00033

£4.99

Selecting Contact Form: 4 Pin Relay vs 5 Pin Relay

Pin architecture determines circuit switching behavior. A 4 pin relay typically uses an SPST contact form, providing a simple on-off path for single loads like auxiliary lights or horn circuits. Standard models like JD1912 offer a normally open contact configuration for standard switching duties.

A 5 pin relay provides an SPDT contact form, also identified as 1 Form C or 1NO 1NC. This layout features five terminals to alternate power between two circuits or provide a continuous closed circuit until energized. We also supply 2-pin options, such as the Z-0269 flasher designed for motorcycle and scooter LED turn signals, and multi-terminal 7 Pin configurations.

SPST (4-Pin): JD1912 style for basic isolated high-current circuits.
SPDT (5-Pin): 1NO 1NC configuration for alternating loads or car alarm circuits.
2-Pin Flasher: Model Z-0269 with adjustable flash frequency of 50 to 200 cycles/min for LED blinkers.

Current Ratings and DC Coil Voltages

Matching the continuous load current to contact capacity prevents contact welding and terminal overheating. Our catalog covers ratings from 30A up to heavy-duty 80A and 100A / 200A ratings, with 40A being standard across common Bosch Style units.

Coil voltage must match your system electrical architecture. We stock 12V DC units for standard passenger vehicles and powersports, alongside 24V DC and dual 12V / 24V DC relays for commercial trucks, vans, and marine systems.

Standard DC Loads: 30A, 35A, and 40A ratings for general lighting and switching.
High-Current Switching: 80A and 100A / 200A units for heavy machinery loads.
Voltage Profiles: Dedicated 12V DC, 24V DC, or dual 12V / 24V DC coils.

Harness Sockets and Environmental Protection

Vehicle chassis and engine bays expose electrical connections to vibration, road spray, and dirt. Compel supplies automotive relay with harness socket assemblies featuring color-coded wires, 105mm wire lengths, and copper terminal construction to maintain low electrical resistance.

For exposed mountings on trucks, vans, and marine hulls, select units labeled waterproof or splash-proof. Sockets with interlocking brackets allow clean ganging inside distribution panels and under-dash enclosures.

Copper Terminals: Deliver stable conductivity under continuous current draw.
Sealed Housings: Select waterproof or splash-proof enclosures for exterior chassis wiring.
Pre-Wired Assemblies: Include socket bases with color-coded wiring for rapid panel installation.

Buying guide

Choosing Automotive Relays

What is the difference between an SPST and an SPDT automotive relay?: An SPST automotive relay has four pins and acts as a simple on-off switch across one circuit. An SPDT automotive relay uses five pins to route power between two circuits, providing one normally open and one normally closed output.
What current ratings are available for automotive switching?: Compel stocks relays rated across various capacities, including 30A, 35A, 40A, and 80A. For heavy equipment and high-current starter circuits, we offer units handling 100A / 200A.
Can I use an adjustable 2-pin relay for LED blinker conversions?: Yes, models like the Z-0269 2-Pin relay operate on 12V DC and support turn signals rated at 21W x 2 + 3.4W. They provide an adjustable flash frequency between 50 to 200 cycles/min for motorcycles and scooters.
When should I install a waterproof relay harness instead of an unsealed socket?: Install waterproof harness kits whenever the relay sits in an engine bay, along a commercial truck chassis, or in marine environments. Sealed waterproof housings stop road spray and washdown moisture from oxidizing the copper terminals.