The operation of the outboard motor is impossible without a reliable source of energy, and in most modern models with an electric starter, this role is played by a battery. However, to prevent the battery from running out while driving, a special unit is built into the electrical circuit, known as a battery. charge-relay It's the component that converts the alternating current generated by the magneto stator into the direct current needed to recharge the battery.
Many water-engines are faced with a situation where after a walk the battery is discharged, although there is no apparent reason for this. rectifier-regulatorUnderstanding how it works and being able to conduct basic diagnostics can save you from suddenly stopping on the water or having to light up the engine on the dock, and in this article we will discuss the device, the symptoms of malfunctions and the nuances of choosing a replacement.
It is worth noting that charging systems can vary significantly depending on the manufacturer and engine power. Low-power two-stroke motors often use simple circuits, while four-stroke engines use more complex electronic control units. It is critical to understand that a burned-out charging relay is often a consequence rather than a root cause, and may indicate problems with stator windings or poor mass contact. Ignoring this fact will lead to a rapid breakdown of the new installed element.
Operating principle and charging system design
The fundamental task of the relay is to stabilize the voltage supplied to the battery. The outboard motor stator generates alternating current, the parameters of which are directly dependent on engine speed. At high speeds, the voltage can reach dangerous values that can boil the electrolyte or damage electronics, and at idle speed - be insufficient to charge.
Inside the device's housing are diode bridges that straighten the current, and thyristors or transistors that regulate the output voltage. Tohatsu or YamahaThe principle of operation is based on cutting off excess energy: when the voltage exceeds a predetermined threshold (usually about 14.4-14.7 V), the regulator closes the charging winding by mass or stops the pulses.
The reliability of these components directly affects the life of your battery, and if the relay does not perform its stabilization function, the battery will either undercharge, which will lead to sulfation of the plates, or recharge, which will cause corrosion of the grids and electrolyte ejection. regulator It is a guarantee of long life of your onboard power grid.
Install the charging relay on the metal surface of the motor through the thermal paste, as when it is working it is very hot and requires effective heat removal.
Symptoms of malfunction of the charging relay
Diagnosing the electrical part of an outboard motor often begins with an analysis of the behavior of the battery and the starter. The first and most obvious sign of a relay malfunction is a systematic lack of charge. You may notice that the motor starts with difficulty after a short parking, even though the battery is new or in good condition.
But the symptoms may be less obvious, for example, when the engine is running at high speeds, there may be unstable operation of the ignition system or dim glow of the indicators on the dashboard. tension affects not only the charging of the battery, but also the operation of the ignition coils and the CDI unit.
Also, you should pay attention to the external signs. The overheating of the relay itself, the smell of burning or the melting of the insulation of the wires in the charging circuit are direct signals that the system is operating in emergency mode. Sometimes a faulty relay can create a short circuit, which leads to the combustion of the fuse of the charging circuit immediately after it is replaced.
- ⚡ The battery is quickly discharged even after a long operation of the engine at high speeds.
- 🔋 The voltage at the terminals of the battery with the engine running does not grow above 12.5-12.8 V.
- 🔥 The case of the relay charging is strongly heated or has traces of thermal effects.
- 💡 The lighting lamps and indicators on the dashboard flash or change brightness depending on the revolutions.
Diagnostic methods of multimeter
To determine the fault accurately, you need a digital multimeter. The initial check is done on the engine running. The voltage is measured directly at the battery terminals under different engine modes. At idle speeds, the voltage should be just above 12 V, and when you increase the speed to medium and high, it should rise to the range of 13.8-14.5 V.
If the voltage is still or is growing slightly, you should check the integrity of the circuit from the stator to the relay and from the relay to the battery. Often the problem is not in the relay itself, but in oxidized contacts or a wire break. contact groups and connectors, as the marine environment contributes to rapid corrosion.
Then you check the rectifier itself, and you call the diodes with the multimeter in diode check mode, and you have to show resistance in one direction, and you have to check the cliff in the other, and if the multimeter shows a short circuit or a cliff in both directions, the component is faulty, and you have to take the relay off the motor in more detail.
☑️ Diagnostics of the charging system
Typical causes of failure
Understanding the causes of a failure helps to avoid a repeat of the situation. One of the most common causes of relay combustion is poor contact in the mass chain. If the engine is not well connected to the boat hull or battery, there is nowhere to go, and the voltage surges penetrate the internal electronics of the regulator. mass It is the key to the health of all electricians.
The second common reason is that you're using a battery with the wrong capacity or type, and if you replace a regular battery with a model with a significantly lower capacity, the relay can run in a constant overload mode, trying to charge the battery with too much current, and vibrations that can cause internal contacts to break in soldering are also harmful.
And you can't ignore the natural wear and tear. Over time, diodes degrade, and the thermal cycle (heat-cooling) destroys the structure of semiconductors. Water-cooled motors sometimes get moisture inside the relay body because of the breakdown of the ods or seals, which causes instant short circuits.
⚠️ Warning: Never start a motor with the battery turned off. In this case, the charging relay loses its buffer capacity, and voltage surges from the stator will instantly disable it, and can also damage the ignition unit.
Criteria for the selection of replacement component
When looking for a replacement, it is important to consider not only geometric dimensions, but also electrical specifications. The charging relay is selected strictly according to the model of the motor and its power. Installing a universal relay by eye can lead to improper charging mode. The key parameters are maximum charging current and threshold cut-off voltage.
Original parts from manufacturers like Mercury, Johnson/Evinrude or Honda They guarantee full compliance with specifications, but often have high cost. The market offers many quality analogues that are cheaper, but require careful study of the connection scheme. It is important to check the number of pins and their purpose, since the pinning can differ even for visually similar blocks.
When choosing, pay attention to the quality of the case. It must be sealed and made of materials that are resistant to aggressive environments and high temperatures. Cheap Chinese counterparts often sin by poor soldering and using diodes with low current specifications, which reduces their service life.
| Parameter | Original (OEM) | Quality analogue | Cheap analogue |
|---|---|---|---|
| Price. | High. | Medium | Low. |
| Accuracy of voltage | High (14.4V) | Medium (14.2-14.6V) | Low (scattering) |
| Resource | 5 years | 2-4 years | 1 year or less |
| Tightness | Complete. | Good. | Often broken. |
Replacement process and nuances of installation
Replacing the charging relay is a procedure that is available to the owner with basic mechanical skills. The first step should always be to turn off the battery's sub- terminal, which will protect you from accidental short circuit and electric shock, and then you need to dismantle the motor casings to access the electrical part.
Disconnect the wire connectors from the old relay. It is recommended to take a pre-picture of the connection circuit or mark the wires with a marker so as not to confuse them when installing a new element. Often the wires are color-coded: yellow or white is the entrance from the stator, red is the exit to the battery, black is the mass. However, the colors can vary, so check with the manual is required.
When installing a new relay, make sure to clean the seat of dirt, oil and oxides. Apply a thin layer of thermopaste to the relay contact area (if it is attached to the motor metal) to improve heat transfer. Tighten the fasteners safely, but without fanaticism, so as not to damage the body. After assembly, check the charging voltage.
What if the new relay is also burned?
If a new relay burns out immediately after installation, don't rush to put a third one. There's a 90% chance the problem is in the stator windings (interturn circuit) or in the breakdown of the high-voltage wire insulation. You need to call the stator for resistance and breakdown mass. Also check the condition of the diode bridge inside the magneto itself, if that's what the motor design implies.
Prevention and maintenance of electricians
To make the relay last long, you need to regularly carry out preventive measures: at least once a season, you should check the tightening of the battery terminals and mass contacts on the engine. oxidation of the contacts increases resistance, which leads to a drop in voltage and overheating of connections.
Use special spray preservatives for electrical contacts after each washing of the engine or entering salt water, this will create a protective film and prevent corrosion. Also keep the hood clean: the accumulation of dirt and oil on the case of the relay worsens cooling.
Regularly check the level of electrolyte in the batteries in service and the density of charge. Deep discharge or overcharging is harmful to the entire system. Timely replacement of the old battery with a new one will also prolong the life of the charging relay, since the old battery has high internal resistance and does not take charge well.
Regular visual inspection of wiring and cleaning of mass contacts prevents 80% of sudden failures of the charging system on water.
⚠️ Note: When installing additional energy consumers (echo sounders, navigators, winches), make sure that the standard charging relay copes with the increased load. You may need to install an additional rectifier or replace the battery with a model with a larger capacity.
Frequently Asked Questions (FAQ)
Can a outboard motor be operated without a relay charge?
In the short run, yes, the motor will run on a charged battery, but you can't do that for long: the battery will run out quickly and the engine will die, and without a regulator, the voltage from the stator can jump, which is dangerous for the ignition system (CDI) and can damage the candles or the coil.
Why is the relay on the outboard motor warmed?
Heating is a normal workflow, because when you straighten and adjust the current, you get heat, but if the body gets so hot that you can't touch it with your hand, or if the plastic is melted around, it's a sign of a malfunction (diode breakdown) or poor mass contact, working in overload mode.
What voltage should be on the battery when the engine is running?
The normal range is 13.8 to 14.5 volts at above-idle speeds. When idling, the voltage can drop to 12.5 to 13.0 V, because the stator produces little power. If the voltage is above 15 V, the relay does not turn off charging, which leads to boiling of the battery.
Can I check the relay without being removed from the engine?
No, it's not. You can only indirectly judge its performance by the voltage at the battery terminals when the engine is running, and to check the diodes and internal circuits of the relay, you have to dismantle and call it a multimeter when it's off.