A smart door lock continuously energized for over 24 hours can become too hot to touch even when the ambient temperature is only 25 degrees Celsius, eventually shutting down due to a burned-out coil. This type of overheating failure caused by long-term energization is a bottleneck that many hardware development teams frequently encounter during the product testing phase.
The Hidden Danger of Traditional Solenoids Burning Out at High Temperatures: Why Do We Need Latching Solenoids?
Why do traditional linear solenoids require a continuous flow of current to maintain their attracted state? This is because traditional designs must rely on continuous electrical energy to overcome spring tension; once power is cut off, the mechanism resets immediately.
In contrast, modern hardware architectures no longer tolerate such useless energy consumption, especially in battery-powered Internet of Things (IoT) devices, where every milliampere-hour of battery capacity determines the product’s market lifespan.
A 100% duty cycle in traditional solenoids means the coil temperature can soar to over 80 degrees Celsius in just a few dozen minutes, which not only accelerates the aging of the insulated enameled wire but also significantly reduces system safety.
What cannot be seen on the blueprints is that when the ambient temperature rises and overlaps with the coil’s self-heating, the resistance increases accordingly, leading to a decrease in holding force and creating a vicious cycle of system failure.
Thermal Accumulation Effect Under Continuous Energization
To be frank, achieving zero-power holding without sacrificing holding force requires the introduction of a permanent magnet (Permanent Magnet) into the magnetic circuit design.
Energy Saving Differences Between Bi-stable and Mono-stable: Analysis of Latching Solenoid Power Saving Principles
Taking a typical bidirectional latching solenoid as an example, when a pulse current (Pulse Current) passes through the coil, the generated electromagnetic field adds to the magnetic field of the internal permanent magnet, driving the plunger to the end position where it is firmly held by the permanent magnet. At this point, even if the power is cut off immediately, the plunger remains in place, requiring absolutely no electrical energy to maintain its position.
Synergistic Mechanism of Permanent Magnets and Electromagnetic Coils
This mechanism of using positive and negative pulse signals to switch states allows the electromagnetic coil to consume power only at the instant of movement (usually less than 100 milliseconds).
So, how do we release the plunger when needed? The answer is to apply a reverse pulse current to generate a magnetic field opposite to that of the permanent magnet, thereby canceling out the attraction force. At this point, the internal spring can easily push the plunger back to its initial position.
- Instantaneous Energy Consumption: Energized only for 50 to 100 milliseconds during state switching.
- Static Zero Power Consumption: Power consumption is zero when maintaining the attracted or released state.
- Low Heat Accumulation: Since the energization time is extremely short, the coil generates almost no heat.
Selection Guide for Long-Term Energized Products: Which Devices Are Best Suited for Switching to Latching Solenoids?
Although latching solenoids have an absolute advantage in power saving, their control circuits are relatively complex, requiring a bidirectional drive circuit (H-Bridge), which is fundamentally different from traditional unidirectional switch control.
Automation equipment operating 24/7, electronic safety locks, and outdoor measurement instruments requiring extreme power savings are currently the most successful and typical scenarios for implementing this technology.
Applications in Smart Locks and Green Energy Storage Systems
It must be admitted that for applications with frequent opening and closing (such as operating several times per second), the energy-saving advantage of latching solenoids will be compromised by the frequent pulse currents, in which case traditional solenoids may still be a lower-cost choice.
Imagine in a remote solar energy storage grid where a circuit breaker (Circuit Breaker) needs to remain closed for long periods. If a traditional solenoid is used, the energy wasted each year to maintain energization would be very significant. After switching to a latching design, the self-consumption of that node drops to almost zero.
In battery-powered applications where a single energized hold time exceeds 10 seconds, switching to latching solenoids can reduce system power consumption by more than 90%, making it a decisive design choice for extending equipment battery life.
Reducing Power Consumption and Controlling Residual Magnetism: Shih Shin Technology’s Customized Solenoid Solutions
Once the power consumption issue is resolved, can design engineers rest easy?
However, another silent killer remains hidden in magnetic circuit design: the issue of residual magnetism caused by material physical properties.
A release delay of 10 milliseconds often decides the life or death of a safety valve. Shih Shin Technology’s approach in similar cases is to optimize the magnetic circuit structure through precise electromagnetic simulation, and select special alloy materials with high magnetic permeability and low residual magnetism. While ensuring holding force, this minimizes the impact of residual magnetism, achieving smooth demagnetization and reset actions.
Although adopting special alloy materials slightly increases the initial procurement cost, from the perspective of battery replacement costs and maintenance frequency over the product lifecycle, this technological trade-off clearly brings higher long-term return on investment for brands.
In actual testing, choosing latching solenoids is not only to solve the heating problem, but also a crucial step for the product towards green, low-carbon design. Through reasonable magnetic circuit configuration and control logic, development teams can find the best balance between performance and power consumption, giving products stronger market competitiveness.
It is recommended to provide operating frequency and expected battery life data to the technical team in the early stages of product development, so that we can evaluate the most cost-effective customized latching solenoid solution for you within 24 hours.
