Blog

You're out on the water, the sun is shining, and your marine electronics are humming along... or are they? While you might not see it, there's a silent power thief lurking in your boat's wiring: voltage drop.

It's a common, often misunderstood, issue that can significantly impact the performance and longevity of your valuable marine electronics.

What is Voltage Drop?

In the simplest terms, voltage drop is the reduction in electrical potential (voltage) as electricity travels through a conductor (wire). Think of it like water flowing through a hose. If the hose is too long, too narrow, or has kinks, the water pressure at the end will be lower than at the beginning. Electricity works similarly. As current flows through a wire, some of the electrical energy is converted into heat due to the wire's resistance, resulting in a lower voltage at the device end compared to the battery end.

Why Does Voltage Drop Matter for Marine Electronics?

Marine electronics, unlike simple lights or pumps, are often quite sensitive to voltage fluctuations. Even a small drop in voltage can lead to a host of problems:

• Underperformance: Your fishfinder might not display as clearly, or your GPS might be slow to acquire satellites for example. Devices designed to operate at 12V might only be receiving 10V or 11V, leading to them not functioning at their peak.
• Intermittent Operation: Devices might inexplicably shut off, reset, or behave erratically, especially when other high-current devices are turned on.
• Damage and Reduced Lifespan: While modern electronics often have some built-in tolerance, consistently running them at lower-than-specified voltages can stress internal components, leading to premature failure and replacements. Side note: for some reason we have noticed Humminbird to be more sensitive than Lowrance and Garmin products- at least in the stuff we see coming into the shop.
• Battery Drain: While not directly causing battery drain, voltage drop means your devices are working harder to achieve their desired function, potentially drawing more current and thus draining your battery faster than if they were receiving their full voltage.

The Culprits Behind Voltage Drop

Several factors contribute to voltage drop:

1. Wire Gauge (Thickness): This is the biggest factor. Thinner wires (higher gauge numbers, e.g., 18 AWG) have higher resistance than thicker wires (lower gauge numbers, e.g., 10 AWG). For a given current, a thinner wire will experience a greater voltage drop.
2. Length of Wire: The longer the wire, the more resistance it has, and thus the greater the voltage drop. This is why devices far from the battery are more susceptible.
3. Current Draw (Amperage): The more power a device consumes (higher amperage), the greater the voltage drop will be for a given wire size and length. A high-power stereo will experience more voltage drop than a small LED light.
4. Connections and Terminations: Poorly crimped connectors, loose terminals, corrosion, and inadequate splices all add resistance to the circuit, contributing significantly to voltage drop. These "kinks in the hose" can be just as problematic as an undersized wire.
5. Temperature: While less significant in most practical marine applications, higher temperatures can slightly increase wire resistance, leading to a marginal increase in voltage drop.

How to Combat Voltage Drop

The good news is that voltage drop is largely preventable and diagnosable:

1. Use the Correct Wire Gauge: This is paramount. Always consult the manufacturer's recommendations for your electronics and use a wire gauge chart to determine the appropriate size based on the device's current draw and the length of the wire run. When in doubt, go one size larger than what seems necessary. It's cheap insurance!
2. Minimize Wire Lengths: Plan your wiring runs efficiently to keep them as short as possible.
3. Ensure Quality Connections:
   • Crimping: Use high-quality marine-grade connectors and a proper crimping tool. Pull on crimps to ensure a secure connection.
   • Soldering (with caution): While sometimes used, soldering alone can be brittle in a vibrating marine environment. If soldering, ensure it's in conjunction with a good mechanical connection and heat shrink. (We don't solder connections here)
   • Corrosion Prevention: Use heat-shrink tubing over all connections to seal them from moisture and prevent corrosion, which adds resistance.
   • Clean Terminals: Regularly inspect and clean battery terminals and other connections.
4. Dedicated Circuits: For high-current or sensitive electronics, consider running dedicated, properly sized circuits directly from the battery (with appropriate fusing, of course).
5. Measure and Monitor: The best way to diagnose voltage drop is to measure it.
   • At the Battery: Measure the voltage at your battery terminals when the device is off and then when it's on.
   • At the Device: Measure the voltage directly at the power input of your electronic device when it's operating.
   • The Difference is the Drop: The difference between the voltage at the battery and the voltage at the device is your voltage drop. A general rule of thumb is to aim for less than a 3% voltage drop for critical electronics.

Understanding and addressing voltage drop is crucial for the optimal performance and longevity of your marine electronics. By paying attention to wire gauge, connection quality, and proper circuit design, you can ensure your marine electronics receive the power they need to keep you safe, informed, and entertained on the water. A little proactive maintenance now can save you a lot of headaches and expense down the line.