The KLB (V5) 40A Switching Capability Automotive Relay from NINGBO KEYONG JINGSHENG ELECTRICAL APPLIANCE CO., LTD. is a reliable high-current relay designed for automotive and industrial applications, offering 1 Form A / 1 Form B contact configuration with up to 40A switching at 14VDC for stable control of fans, lighting, heaters, and motors. It operates in harsh environments from -40°C to +125°C, supports 12V/24V coil options, and provides Wash Tight (S) and Flux Proof (Z) versions for better protection, while its durable contact design and RoHS compliance ensure long service life and safe, cost-effective performance for OEM buyers.
1. High Switching Capacity (40A Load Handling)
Designed to handle up to 40 amps, making it suitable for medium-to-high power automotive applications.
2. Compact & Space-Saving Design
Small footprint allows easy integration into tight automotive wiring systems and fuse boxes.
3. Reliable Electrical Performance
Stable contact resistance
Strong arc suppression
Consistent switching performance under vibration and heat
4. Automotive-Grade Durability
Built to withstand:
High temperature under-hood environments
Vibration and mechanical shock
Electrical noise and surges
5. Energy Efficient Control
Low coil power consumption ensures minimal load on control circuits.
6. Long Service Life
Designed for repeated switching cycles with minimal wear on contacts.
When selecting a suitable relay, consider the following factors:
1. Load Current Requirements
Ensure the relay supports at least 40A or higher for peak load conditions.
2. Voltage Rating
Most automotive relays are designed for 12V DC or 24V DC systems. Match your vehicle system voltage.
3. Contact Configuration
Common types:
SPST (1 Form A) – simple ON/OFF control
SPDT (1 Form C) – switching between two circuits
4. Operating Environment
Check:
Temperature range (engine bay vs cabin use)
Vibration resistance
Moisture or dust protection requirements
5. Terminal Type
PCB terminals (for integrated circuits)
Quick-connect terminals (for wiring harness systems)
6. Application Type
Different applications may require:
High inrush current tolerance (motors, fans)
Continuous load stability (lighting systems)
| Contact arrangment | A/B |
| Voltage drop(at 10A) | ≤200mV |
| Contact material | Silver alloy:AgSnO₂In₂O₃、AgSnO₂、AgNi |
| Contact rating | 30A 40A 14VDC |
| Max switching voltage | 50VDC |
| Max switching current | 40A(Resistive 14VDC) |
| Min contact load | 1A 6VDC |
| Electrical endurance(Frequency:900 ops/h) | 1×10⁶ps |
| Mechanical endurance(Frequency:18000 ops/h) | 1×10'ops |
| Power consumption(W) | 1.5W | 1.7W | 1.5W | 1.7W |
| Nominal voltage(VDC) | 12 | 12 | 24 | 24 |
| Coil resistance(Q±10%) | 96 | 96 | 384 | 384 |
| Parallel resistance(2) |
|
680 |
|
2700 |
| Pick-up voltage(Max) | 65%(Nominal voltage) | |||
| Drop-out voltage(Min) | 10%(Nominal voltage) | |||
| Max allowable overdrive voltage(VDC) | 150%(Nominal voltage) | |||
| Insulationlevel | Class B/Class F | |
| Insulation resistance | 100MΩ(500VDC) | |
| Dielectric strength(Leakage current 1mA) | Dielectric strength (Between coil and contacts) | 500VAC minute |
|
|
Dielectric strength (Between open contacts) | 500VAC minute |
| Operate time(at nominal voltage) | ≤10ms | |
| Release time(without diode)(at nominal voltage) | ≤10ms | |
| Humidity | 5%～85%RH | |
| Ambient temperature | -40℃~+125℃ | |
| Vibration resistance | 5Hz~22.3Hz 10mm Double amplitude | |
|
|
22.3Hz~500Hz 98m/s² | |
| Shock resistance | 294m/s² | |
| Weight | Approx299 | |
| Construction | Dustproof | |
This type of relay is mainly used in automotive electrical systems where high current loads must be controlled reliably without overloading the control circuit.
Typical applications include:
Headlights, fog lights, and auxiliary lighting systems
Air conditioning compressors and cooling fans
Fuel pumps and engine control circuits
Power windows, central locking systems
Horn systems and wiper motors
Electric vehicle auxiliary circuits
In short, it enables low-power signals to safely control high-power automotive devices.
Q1: What does 40A mean in an automotive relay?
It means the relay can safely switch electrical loads up to 40 amperes under specified conditions.
Q2: Can this relay be used for LED lighting systems?
Yes. It is commonly used for LED headlights, auxiliary lights, and lighting control circuits.
Q3: What happens if the load exceeds 40A?
Exceeding the rated current may cause:
Contact overheating
Welding of contacts
Reduced lifespan or failure
Q4: Is it suitable for all vehicles?
Yes, as long as the voltage (12V/24V) and load requirements match the relay specifications.
Q5: How long does an automotive relay last?
Under normal conditions, a high-quality 40A relay can last hundreds of thousands to millions of switching cycles.
Q6: What is the difference between 30A and 40A relays?
30A relay: suitable for lighter loads (basic accessories)
40A relay: designed for heavier loads like motors, compressors, and high-power lighting
Address
350 Renmin North Road, Hengxi Town, Yinzhou District, Ningbo City, Zhejiang Province, China
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