Bi-Stable vs. Auto-Latching Relays

When you're managing power on a boat, choosing the right battery switch relay can make a big difference in system efficiency and reliability. Two of the top names in the marine world, Blue Sea Systems and Egis Mobile Electric, offer high-quality relays designed for marine use. But before picking one, it’s important to understand the difference between bi-stable and auto-latching relays, and how each brand implements them.

Bi-Stable vs. Auto-Latching

• Bi-Stable Relays (also known as latching relays) only draw power during switching. Once turned on or off, they hold their state with no continuous power draw. Great for conserving battery power.

• Auto-Latching Relays have built-in control logic to automatically connect or disconnect based on voltage, ignition, or other signals. They often have a small standby draw to support internal circuitry.

Blue Sea RBS 

The Blue Sea RBS (Remote Battery Switch) is a rugged, marine-grade relay that comes in two distinct models:

• A bi-stable version, which operates with a momentary switch and draws no current while idle.

• An auto-latching version, which includes voltage-sensing and logic for automatic control.

These are separate SKUs, so when choosing a Blue Sea RBS, it’s important to know which style you need from the start. There's no cross-functionality between them; it's either one or the other.

Best for: Users who want a reliable, purpose-built relay with either manual or automated operation, and are clear on which version suits their setup.

Egis Mobile Flex – One Device, Multiple Modes

The Egis Mobile Flex Relays offer a versatile alternative. Rather than having separate products, the Egis Flex line is programmable, allowing the same relay to function in bi-stable, auto-latching, or even standard continuous modes, depending on your needs.

With the Egis Flex, you can configure:

1. Manual or automatic control modes
2. Voltage thresholds for auto-latching
3. Momentary or maintained control inputs
4. Wake/sleep behavior for power savings

This makes it ideal for boat owners or installers who want flexibility or may evolve their electrical system over time.

Best for: Installers, tech-savvy users, or anyone who wants to fine-tune how the relay behaves, without swapping hardware.

So, Which Relay Is Right for You?

Final Thoughts

If you know exactly what you want and prefer a simple plug-and-play setup, Blue Sea’s RBS line is a proven choice, just be sure to choose the correct model for bi-stable or auto-latching behavior.

If you're looking for a more flexible or customizable solution, the Egis Mobile Flex gives you the ability to adapt over time without changing hardware, making it a future-proof option for evolving systems.

Need help deciding? Reach out to our team, we’re happy to walk you through which relay best fits your boat and electrical system.