Heavy-Duty Mini Relay — R4-1280R 80A 12V 4-Pin N/O Resistor

Q: What is a heavy-duty mini relay?

A: A mini relay rated to switch higher continuous current than a standard mini-ISO relay. Standard mini-ISO relays run 20 to 40A; heavy-duty versions like the R4-1280R push the same physical form factor up to 80A continuous by using thicker contact material and higher-rated blade terminals. Drops into the same relay base, carries more load.

Q: What does ‘resistor protected’ mean?

A: A resistor sits across pin 85 and 86 (the coil terminals). When the relay drops out, the collapsing magnetic field in the coil pushes a reverse voltage spike back into the circuit; the resistor burns that energy off before it reaches anything sensitive. Not polarity sensitive, so the coil can be wired either way. The alternative is a diode-protected version, which is polarity sensitive and typically shows a longer drop-out time.

Q: What size cable and fuse should I run with an 80A relay?

A: For 80A continuous at 12V on short automotive runs, use 6mm² (10 AWG) minimum on the pin 30 and pin 87 switched side, and fuse the pin 30 feed at the battery to match the downstream circuit, not above 80A. For runs longer than 2 metres, step up to 8mm² (8 AWG) to keep voltage drop under 3%. The coil side (pin 85 and 86) draws about 0.16A so trigger wires can be 1.0mm² or smaller.

Q: Can I use this to drive a winch?

A: No. 4WD winches draw 200 to 500A under load, well above the 80A ceiling of this relay. For winches, use a dedicated 500A continuous-duty solenoid or an Albright-style motor contactor. This relay is for mid-current accessories like driving lights, radiator fans, air compressors and fuel pumps where draw stays under 80A.

Q: Can I switch LED driving lights with it?

A: Yes, well within rating. A 300W LED light bar draws about 25A at 12V, and a pair of 9-inch LED driving lights sits around 10A total. The 80A ceiling leaves plenty of headroom for a whole LED bar network driven off one relay. Watch for inrush spikes on LED drivers with large capacitors; the 80A continuous rating absorbs those without issue.

Q: What is the difference between this 80A relay and a standard 40A mini relay?

A: Same physical form factor and same pin pattern; both fit the standard mini-ISO 4-pin base. The 80A version uses thicker contact material inside and higher-rated blade terminals so it can carry twice the continuous current without heating up. If an accessory draws more than 30 to 40A continuous, step up to the 80A version to leave a safety margin.

Q: Will it work in a 24V vehicle?

A: No. The coil is wound for 12V DC only; feeding 24V to pin 85 and 86 will burn the coil out quickly. For 24V trucks, buses or industrial equipment, use the 24V equivalent in the Britax catalogue.

Q: Does the pin pattern fit a Narva or Hella mini relay base?

A: Yes. The standard mini-ISO 4-pin pattern is used by every major brand (Britax, Narva, Hella, MTA, Durite, Tyco); the pin spacing and dimensions are an industry standard. Any mini-ISO 4-pin base takes any mini-ISO 4-pin relay regardless of the brand on either part.

Q: Can I mount it on its side or upside down?

A: Yes. The relay is sealed and orientation does not affect the magnetic circuit. Mount in whichever orientation fits your fuse-and-relay panel or auxiliary tray.

Q: What is the coil current draw?

A: About 0.16A at 12V, or roughly 1.9W. Low enough that the trigger side (pin 85 and 86) can be wired through a standard dash switch, an ignition-sense tap, a timer, or a low-current output on a BCM or auxiliary controller without worrying about contact rating on the trigger device.

Q: What is the difference between a resistor-protected and a diode-protected relay?

A: Both solve the same problem; stopping the coil’s collapse-spike from reaching sensitive electronics. A resistor burns the energy off as heat, is not polarity sensitive, and drops out faster. A diode shorts the spike back through the coil, is polarity sensitive (reverse the coil wires and it stays stuck on), and typically shows a slower drop-out. For general automotive use with modern ECUs, either is fine; resistor-protected is more forgiving to install.

Q: What warranty does Britax provide?

A: 12 months against manufacturing defects on the relay when run within its rated 12V 80A specification. The warranty covers coil burnout within rating, contact weld-up within rating, and housing integrity; it does not cover loads above 80A continuous, reversed battery polarity on pin 30, mains voltage, physical damage, or water immersion.