If you’ve ever gone out to your vehicle only to discover that the battery is dead, you know how it feels. If you’ve ever been out on the water on a boat and discovered that the battery has died, you know how awful it feels! Thus, the issue arises.
Boats generally have alternators. One can check if their boat has an alternator by attaching a voltmeter to their battery while the boat is moving. If the reading exceeds 13 volts, then the boat probably has a properly functioning alternator. If not, then the alternator may be absent or damaged.
What they charge the batteries at in terms of capacity and load is another matter. Consider the following when purchasing a boat with outboard or while setting up your boat and electronics.
Are boat motors capable of charging the battery?
The majority of outboard motors (including those without an electronic starter) are capable of charging a battery in the same way that your car’s engine can. Outboard motors with a large displacement do this by default.
The primary components required are as follows:
- Generator coil (s) that generate unregulated alternating current (AC) as a result of the motor’s rotation
- Regulator/rectifier for converting the coil output to regulated direct current appropriate for battery charging.
How can I determine whether or not my boat has an alternator?
The most surefire method to determine this is to connect a voltmeter to your outboard’s battery terminals when it is operating at approximately mid-throttle or high idle speed. If the voltage is more than 13 volts, you have an alternator that is operating properly.
How is a marine alternator different from a vehicle alternator?
The main aim of vehicle design is to maximize fuel economy via weight reduction. As a result, contemporary car alternators are constructed of lightweight materials and are designed to accommodate tiny batteries and low electrical demands. They are incapable of supporting large loads in the absence of external airflow for cooling.
Continuous-duty, high-output alternators are required for industrial alternator applications. They must be designed to endure and operate safely. Marine alternators, for example, need more power than standard vehicles and trucks to power lights, radio transceivers, navigation systems, AC/DC inverters, watermakers, pumps, and winches.
Additionally, marine engines are often housed in covered chambers to keep them dry and protected from salt spray and moisture. This implies that maritime alternators must be self-cooling or have an extra cooling component while operating at high loads. Marine alternators must also adhere to stringent safety standards not demanded of automobiles.
Features of a Marine Alternator
To fulfill these requirements, marine alternators include characteristics not present in automotive-grade units:
- Spark screens that comply with US Coast Guard regulations are used to remove the alternator as a source of ignition.
- Double-insulation to avoid electrical shock and sparks in moist circumstances.
- Dual fans and a huge heat sink allow the system to self-cool when subjected to heavy, continuous loads.
- Bearings are made of stainless steel, corrosion-resistant alloys, and tough coatings.
- High power at low RPMs to meet the operating circumstances of marine diesel engines
- Battery sensing regulators are used to charge batteries efficiently and to detect battery cell breakdown.
- Positioning and Installation of a Marine Alternator
Given the space limitations inherent in the majority of maritime vehicle designs, it is critical to begin by selecting the proper alternator case size:
- Small case alternators usually have a diameter of 6 inches and a length of 6 inches. They often make use of a single pulley. They typically provide less than 110 amps at 12 volts.
- Large case alternators are about 7 inches in diameter and 7 inches in length and have a maximum output of more than 110 amps. These may need a twin pulley or a serpentine belt system with numerous grooves.
- To provide sufficient power to the biggest engines, an extra-large case alternator or several alternators are used.
The other critical factor to consider when replacing a marine alternator is the foot type. Alternator casings are available with a single foot or with two feet with various lengths between them. On bigger diesel engines, a wider foot spacing is utilized. Certain fittings need spacers to be installed properly. The most critical factors to examine are that all pulleys match and that all belts are aligned.
Regulator Characteristics
Automotive alternators depend on simple voltage regulators, either internal or external, whose primary function is to maintain a charged starting battery. However, since efficiency and battery life are more important in maritime applications, the regulators are more sophisticated, precise, and changeable. Although internally controlled alternators are available, the majority of marine alternators depend on external regulators to provide these characteristics. Numerous options are adaptable to the kind and size of the home battery bank, monitoring equipment, and operational circumstances.
Divergence Between Marine and Automotive Alternators
Historically, automotive and industrial alternators had the same fundamental architecture. However, in recent decades, their design objectives have diverged, and their manufacturing and operating characteristics no longer make them interchangeable, even for comparable load needs. Marine alternators, in particular, must operate better under more adverse circumstances than contemporary automobile alternators.
What is the purpose of a boat alternator?
In most sailboats, the charging system comprises batteries, an alternator, a voltage regulator, and the associated wiring and cables. The charging system’s function is to recharge the batteries while also providing electricity to the boat’s existing loads. The charging system does this by turning the mechanical energy generated by the engine into electrical energy through an alternator.
It is critical to maintaining the correct tension on your alternator belt.
When the battery is drained by electrical loads, the battery voltage decreases. When the voltage falls below a certain threshold, the voltage regulator instructs the alternator to start charging the batteries. Thus, the voltage regulator is a switch that activates and deactivates the alternator up to 12 times per second. When the batteries are depleted and the current demand is high, the alternator will remain on for a longer period of time. When the current demand decreases due to the recharging of the batteries, the alternator freewheels and therefore charges less.
Alternators produce energy via magnetism; sending current through a wire generates a magnetic field around it. Current flows through a wire when it is passed through a magnetic field. The alternator produces energy by spinning a magnetic field in the rotor around a stationary circle of copper windings called the stator. The amperage generated is proportional to the magnetic field strength. The alternator’s output is regulated by the field wire, which converts electricity to a magnetic field in the rotor. On the stator, one amp of field current produces 30 amps of output current.
Alternator belts are essential to the alternator’s effective functioning. As a general rule, a 12-volt alternator’s output to horsepower load ratio is 25:1. A 25-amp alternator will provide roughly one horsepower of load to the drive belt. If you are considering upgrading your alternator to a greater amperage rating, keep in mind that the belts have a maximum load capacity.
A single ‘vee’ belt with a width of 3/8 inch can drive an 80 amp alternator or about 3.5 horsepower. A single ‘vee’ belt with a width of 1/2 inch can support a 110 amp alternator or roughly 4.5 horsepower load. A double ‘vee’ belt with a width of 1/2 inch can support a 310 amp alternator or about 12 horsepower of load.
Horizontal subscription in alternators
Every alternator incorporates a voltage regulator. The voltage regulator regulates the alternator’s output current. Additionally, this regulates the voltage in the boat’s electrical system. The majority of alternators have an inbuilt single-stage regulator that regulates alternator output by switching the alternator on and off. The regulator detects voltage levels at the alternator’s output.
When the battery voltage falls below a certain threshold, the voltage regulator activates the alternator, increasing the magnetic field around it and therefore boosting the current output from the alternator. When the battery voltage hits a certain level (usually about 13.5 volts,) the regulator automatically turns off the alternator.
Most sailboats have bigger battery banks and are always searching for methods to reduce the amount of time their engines run to replenish their batteries. To get the most out of your current alternator or if you’re considering upgrading to a higher output alternator, installing a three-stage regulator will increase your power and decrease the time required to recharge your batteries. The bulk stage, the absorption stage, and the float stage are subdivided into these three phases.
Stage I
The alternator supplies a steady current to the batteries during the bulk stage. The regulator maintains a high amperage until the battery reaches the gassing voltage. This results in more amperage being generated for the battery, reducing the amount of time required to charge your batteries. In contrast to the single-stage regulator, which reduces the output current as the voltage rises.
Stage of Absorption
At the conclusion of the bulk charging step, the batteries will have achieved about 80% of their capacity. At this time, the battery is incapable of handling high current at gassing voltage. At about 14.4 volts, the three-stage regulator shifts to the absorption stage, which lowers amperage to the battery’s natural absorption rate. Charging current greater than the normal absorption rate at this moment produces heat in the battery, reducing its life.
Stage of Float
The three-step regulator will transition to the float stage at the conclusion of the absorption stage. The batteries are now fully charged. The regulator lowers the voltage to about 13 volts. When the voltage decreases, the regulator supplies the battery with enough current to maintain the voltage. As a result, the battery “floats” at this voltage level. If you are considering updating your charging system, keep in mind that the output wire from the alternator to the starter should be larger.
This wire should be capable of carrying the alternator’s maximum current. Additionally, connecting the same size wire and grounding the alternator casing will assist in improving the system’s efficiency. Next month, we’ll look at your boat’s batteries, the different types/sizes available, and how to properly charge and maintain them to maximize their useful life.
Conclusion
Any kind of charging mechanism is optional on any type of rope start model.
It would feature a charging system on an electric start outboard. However, there are two distinct types of charging systems:
The first kind is composed of a stator and a voltage regulator. They are two distinct compositions. They actually charge the battery, although slowly. They charge at a rate of about 15 to 20 amps on a medium-sized outboard. They can charge up to 40 amps on a big (V6 engine). However, they charge only while the engine is running at a higher rev range. They usually do not charge while the engine is running at low revs.
The second kind will use a conventional automotive-style one-piece alternator. They may be required to have a maximum output of 100 amps. Regardless of the engine speed, these alternators will usually charge the battery.
Immediately with any system. If you are not taking power from the battery concurrently with its operation. (no lights, radios, or other electronic devices). Either method will recharge the battery in ten to fifteen minutes. If you are simultaneously draining the battery (running accessories), that time definitely increases.
