Scheme of connection of sonar to the battery of the outboard motor

Modern fishing is unthinkable without navigational equipment that allows you not only to find fish, but also to navigate the pond. Many boat owners are trying to minimize the number of batteries on board, wanting to power the sonar from the main starter battery that spins the outboard motor. This solution seems logical: less weight, less wires and do not need to charge the second battery. However, this scheme has its own critical features that must be considered to avoid remaining on the water with a discharged starter or a burned device.

In this article, we will discuss the technical nuances of creating a single energy system for the boat-engine You'll learn how to calculate the wire section correctly, where to install power surge protection, and why you can't just twist the wires with a tape. The soundtrack's integration into the onboard network is key to the steady operation of the engine and the accuracy of the sonar readings.

Before you start, you have to understand the physics of the process. The outboard motor battery is a powerful power source, but it's subject to significant voltage fluctuations, especially when you start the engine, and the sonar is a sensitive electronic device that requires stable power. Garmin, Lowrance or Humminbird Any brand requires compliance with the rules of electrical installation to maintain warranty and performance.

Features of the onboard network of the outboard motor

Onboard network boat-engine The generator installed on the engine generates current to charge the battery, but its output voltage is not perfectly stable. It can fluctuate widely, especially at different turns. In addition, the ignition system (especially CDI on two-stroke motors) creates powerful electromagnetic pulses that are directed to the wires and can cause interference on the sounder screen.

The second important aspect is the starting currents: At the time of switching on the starter, the voltage in the mains can drop briefly to 9-10 volts, and after starting, when the generator comes into operation, jumps of up to 14.5-15 volts and higher are possible. The standard power range for most sonars is from 10 to 24 volts, but prolonged deviations can lead to malfunction or damage to internal electronics.

There is a common misconception that if the sonar formally falls into the voltage range, it can be plugged directly into the battery terminals without additional protection. Voltage surges during the operation of the outboard motor generator can reach 30 volts in the event of a failure of the voltage regulator, which will instantly disable the device. The connection scheme should therefore include buffering and protection elements.

⚠️ Warning: Never connect the sonar directly to the outboard motor generator output. Power should be taken only from the terminals of the battery, which acts as a natural stabilizer and buffer.

Required materials and tools for installation

To get a sounder installed properly, you'll need not only the instrument itself, but also a number of additional components. Don't skimp on wires and fuses, because that's what your boat's fire safety depends on. Cheap materials can oxidize in a single season or melt under load.

The basis of your system will be a copper wire. To power the sonar is usually enough cross section 1.5 mm2 (AWG 16) or 2.5 mm2 (AWG 14), if the length of the wire from the battery to the device exceeds 3 meters. Using a thinner wire will cause a voltage drop at its ends, and the sonar may not turn on or work with errors. Be sure to use the wire in marine insulation, resistant to ultraviolet, salt water and gasoline.

You will also need the following components:

• 🔌 Automatic fuse or a 2-5 Amperes fuse (depending on sonar consumption).
• 🔋 The terminals under the battery bolt (usually under the M6 or M8 bolt).
• 🔧 Thermal shrink tubes for sealing compounds.
• 📏 A cable channel or corrugated cable to protect the wire from mechanical damage.
• 🛠️ Tools: cutters, knife, screwdrivers, thermophene or lighter.

You have to give special attention to the safety lock, which is to be placed as close as possible to the battery plug, which will protect the entire circuit from short circuit, and if you close the wire inside the boat, the safety lock will burn, not the boat itself. safety-guard It is convenient that they can simply be cocked after eliminating the cause of the operation, without changing the consumables.

Connection scheme and sequence of actions

The process of connecting the sonar to the outboard motor battery requires a clear algorithm, and errors in the planning stage of the cable path can cause the wire to rub against the side or be damaged during engine maintenance.

First, locate the sonar and plot the route for the wire. Avoid places where the wire may come into contact with sharp edges, friction or heat. Lay the cable along existing harnesses or in special channels. If the wire passes through bulkheads, be sure to use rubber bushings to ensure that the insulation does not damage the metal.

Next, you'll have to prepare the ends of the wire. You'll need to clean the insulation by the length you need to install the terminals. You'll need to put the shrinkage on the connection points. If you're using a standard sonar connector, make sure the contacts are securely compressed. You'll need to use special sea terminals with a ring that tightly enclose the bolt to connect to the battery.

The connection scheme is as follows:

Component	Color of wire (standard)	Connection point	Protection
Plus sonar (+)	Red.	AKB's plus terminal	Safety lock 2-5A
Minus sonar (-)	Black.	AKB's downside terminal	No (or general safety lock)
Plus the generator.	Yellow/Red	Regulator relay	Safety lock 10-30A
Engine mass	Black/Green	Cylinder block	No.

After you've laid the cable and installed the plugs, connect the sub-conductor sonar to the battery's sub-conductor, then connect the plus-conductor through the safety lock to the plus terminal, only after double checks of all connections, you can supply power, turn on the sonar and check it at different engine speeds.

Protection against interference and tips

One of the biggest problems with electronics boat-engine These can be seen as ripples on the screen, random bands or the complete disappearance of the sonar signal, often caused by the engine ignition system or the operation of the generator.

To minimize interference, avoid running the sonar power cable parallel to high-voltage candle wires or engine control harnesses. If you can't avoid intersections, do it at right angles (90 degrees), which reduces the inductive communication area and reduces the level of tips.

Using ferrite rings (filters) on the sounder power cable can also make a big difference: Ferrit absorbs high-frequency noises, preventing them from entering the device; the ring is placed closer to the sonar power connector; if the regular cable is too short, it can be built up, but the connection places must be well soldered and insulated.

In some cases, the source of interference is poor mass contact. Make sure that the sub-conductor sonar is connected directly to the battery terminal, and not to the hull of the boat or the engine bolt. The body of the boat (especially aluminum) can have a transition resistance that will affect the operation of sensitive electronics.

What should I do if there is interference?

If after proper installation and installation of ferrites interference persists, try to power the sonar through a separate small battery or DC-DC insulator. this will completely untie the power chain and guaranteed to remove tips from the ignition system.

Nuances for two-stroke and four-stroke engines

Connecting the sonar to two-stroke These engines are often equipped with magdinos that produce alternating currents that convert to direct. At low speeds, the voltage can be unstable, and at high speeds, exceed the permissible limits. Owners of two-strokes are advised to be especially careful to install fuses and possibly use additional voltage stabilizers.

Four-stroke motors tend to have a more advanced power system, similar to the car, and there's a full-fledged generator and a relay regulator. But there's also a risk of surges when you drop a gas or start a starter, and four-strokes have much lower-frequency vibrations, so the wires and the sounder itself have to be very reliable.

It is important to consider the mode of operation of the engine. If you often move at low speeds (“trolling”), the generator may not give enough current to charge the battery, and the sounder will consume energy from the battery. During prolonged idling, the battery may become so depleted that it will be impossible to start the engine back, in such cases it is useful to have a superbank or an additional battery for electronics.

Typical errors in installation

Analysis of service center calls shows that most burnt echo sounder problems are due to trivial installation errors, avoiding them to avoid wasting money and time.

The first and most common mistake is that there's no fuse in the power chain, and many people think that because the current is small (about 0.5 A), there's nothing to protect, but if you short-circuit the battery circuit, it can run hundreds of amperes, which will melt the wiring and fire the boat in seconds.

The second mistake is to use twists instead of soldering or plugs. In vibrating and humid conditions, the twist oxidizes, the resistance grows, the contact warms up and eventually burns off. All connections must be either soldered and closed with thermal shrinkage or made with crimping terminals.

The third mistake is to put the wire into the tension, the wire must have a small margin of length, so that the vibration of the engine is not transmitted to the sonar connector and does not shake the contacts, and when the boat moves along the wave, there can be jerks that easily pull the tightly strained cable.

⚠️ Note: Do not use conventional household electrical wiring to lengthen the sonar cable, it has no protection against ultraviolet light and sea salt, and may have a limited cross section, which will lead to a voltage drop.

FAQ: Frequently asked questions

Can I connect the sonar to the lighter of the outboard motor?

Technically, it is possible if the motor is equipped with a 12V outlet. However, such outlets often do not have high-quality protection from moisture and can cause interference. It is better to make a direct connection to the battery through a fuse.

Do I need a separate battery for the sounder?

For short fishing, one battery is enough. For multi-day expeditions or when using high-powered sonars with large screens, it is better to have a separate traction battery so as not to discharge the launch battery.

Why does the sounder turn off when you add gas?

Most likely, there is a drawdown in the voltage in the network due to poor contact in the power supply chain or a weak battery.

What is the minimum cross-section of the wire permissible?

For sonars, the minimum cross-section is 0.75 mm2 for up to 1 meter in length. For standard operating conditions, it is recommended to use a wire with a cross-section of at least 1.5 mm2.

Does the sounder work affect the battery life?

The sonar consumption is negligible (about 5-10 watts) compared to the starter battery capacity, the main discharge is caused by unauthorized discharge of the battery or malfunction in the wiring of the boat.