Servicing Boat Batteries: A Guide To Lead Acid Care

Servicing lead-acid boat batteries is a crucial aspect of boat maintenance. Lead-acid batteries are the most common type of marine battery, and they require regular care to ensure optimal performance and longevity. Here are some essential tips for servicing lead-acid boat batteries:

- Battery Type Awareness: Lead-acid batteries come in three main types: flooded cell, absorbed glass mat (AGM), and gel. Each type has unique characteristics, advantages, and disadvantages. Understanding the specific requirements of your battery type is essential for effective servicing.

- Regular Maintenance: Lead-acid batteries need regular maintenance, including watering (topping up with distilled water) and removing corrosion. It is important to follow the manufacturer's instructions and safety guidelines when performing maintenance tasks.

- Proper Charging: Charging lead-acid batteries correctly is critical for their health and longevity. Overcharging or undercharging can reduce the battery's lifespan and degrade its performance. It is recommended to use a smart three-stage marine battery charger that can be permanently installed and automatically adjusts the charge to avoid overcharging.

- Battery Connections: Clean and well-made connections to the battery terminals are essential for optimal performance. Poor connections can increase electrical resistance, leading to voltage drop and affecting the functionality of electrical equipment.

- Battery Mounting: Batteries should be securely mounted in an acid-proof box or tray to prevent shifting and potential short circuits. Positive terminals should also be covered for safety.

- Battery Monitoring: Using tools like a digital multimeter or a battery hydrometer to monitor the charge level and health of your battery is important. This helps identify any issues and ensures the battery is properly charged.

- Battery Storage: During winter or periods of non-use, proper battery storage is crucial. This includes charging the batteries before storage, disconnecting the negative cable, checking gravity/voltage, and storing them in a cool, dry place where they won't freeze.

- Safety Precautions: When working with lead-acid batteries, safety should always come first. Wear eye protection, avoid smoking, and remove jewellery. Be cautious when handling battery acid, and never look directly into the battery when the filler caps are removed.

Charging lead acid batteries

Charging lead-acid batteries is a crucial aspect of maintaining your boat's power system. Here are some detailed instructions and guidelines to help you effectively charge your lead-acid boat batteries:

Battery Charging Techniques:

The constant voltage charging method is the simplest and most commonly used technique. It involves maintaining a constant voltage to the battery, similar to how a car's charging system works. A voltage regulator is used to adjust the alternator's current flow, ensuring it doesn't exceed the recommended voltage level, typically around 13.35-13.5V for a starter battery.

For sealed lead-acid batteries, constant voltage-current limited charging, also known as the two-step constant voltage method, is recommended to achieve maximum battery service life, capacity, and acceptable recharge time. This method involves applying a DC voltage between 2.30 volts per cell (float) and 2.45 volts per cell (fast) to the battery terminals.

Charging Procedures:

It is important to follow the correct charging procedures to ensure optimal battery performance and longevity. Always select a charger that is specifically designed for charging sealed lead-acid batteries, such as the A-C series of SLA chargers from Power Sonic.

When charging, make sure the battery does not overheat or "boil." Keep an eye on the battery, especially when charging above the manufacturer's recommended C-rate. The battery state-of-health and temperature play crucial roles when fast-charging, so it is important to monitor these factors.

Safety Precautions:

Lead-acid batteries can release explosive gases during charging, especially if they are overcharged. Always ensure that the battery compartment is well-ventilated to prevent the buildup of these gases. Wear gloves when working around batteries to protect your hands from acid, and avoid spilling acid on your clothing or other surfaces.

Charging Frequency:

It is recommended to recharge your battery bank daily to at least 90% capacity and perform a full charge once a week. This practice will help maintain the health and longevity of your lead-acid batteries.

Battery Maintenance:

Regular maintenance is essential to keep your lead-acid batteries in good condition. Periodically check the water level in flooded lead-acid batteries and ensure it never drops below the lead plates. Use deionized water to top off the batteries when needed. Additionally, consider using a battery hydrometer to obtain an accurate reading of the battery's health. This tool measures the specific gravity of the electrolyte fluid, providing valuable insights into the battery's state of charge.

By following these instructions and guidelines, you can effectively charge and maintain your lead-acid boat batteries, ensuring reliable power for your boat's electrical systems.

Safety precautions when handling lead acid batteries

Avoid Contact with Metal

Metal conducts electricity, so touching metal objects that come into contact with a lead-acid battery puts you at risk of electrocution. This includes metal tools, hoist chains, jewellery, watches, and belts.

Prevent Simultaneous Contact with Both Terminals

If both terminals are engaged, an electrical current will pass through anything touching them, including yourself.

Do Not Hand-Guide Batteries During the Lifting/Moving Process

Touching the battery during the lifting/moving process can lead to electrical shock or accidental contact with corrosive battery acid.

Practice Safe Lifting Procedures

Use only specified lifting equipment designed for the purpose of moving batteries and approved for the weight of the battery.

Wear Protective Equipment

Always wear gloves, eye protection, and a hard hat when handling batteries. Gloves and eye protection will guard against battery acid, while a hard hat is important in case a battery swings or falls during the lifting process.

Be Mindful of the Weight

Industrial-sized lead-acid batteries can weigh over 2,000 lbs. Getting your body as close as possible to the battery, lifting with your knees, and getting a co-worker to help you lift are all ways to prevent injury when handling these heavy batteries.

Get Battery Safety Training

Online training courses are available to provide lead-acid battery safety training. These courses will teach you how to handle, recharge, maintain, and clean lead-acid batteries, as well as how to avoid and manage potential hazards such as chemical burns, corrosion, lead poisoning, and electric shock.

Wear the Proper Personal Protective Equipment (PPE)

According to OSHA, the proper PPE for working with lead-acid batteries includes a face shield, an apron, and rubber gloves. The face shield and apron will protect your face and body from the acidic electrolyte, while rubber gloves provide both acid protection and electrical resistance to prevent shock.

Don't Mix Metal with Batteries

Remove all metallic jewellery before working with lead-acid batteries to prevent short circuits, which can result in electrocution and/or burns.

Have the Right Safety Equipment Available

OSHA states that the required safety equipment when working with batteries should include an eye and body wash station, fire protection, and a neutralizing solution.

The different types of lead acid batteries

There are two main categories of lead acid batteries: Flooded (or wet) cells and maintenance-free sealed lead acid batteries. Flooded lead acid batteries are the most common type and are widely used in the automotive industry. They are also the most cost-effective solution in terms of cost per amp-hour.

Flooded lead acid batteries can be further divided into two types: serviceable and maintenance-free. The former requires regular maintenance in the form of watering, equalising charges, and cleaning the terminals. They also need to be mounted upright and can be susceptible to spillage.

Sealed lead acid batteries are commonly known as Valve Regulated Lead Acid (VRLA) or Sealed Lead Acid (SLA). They are available in two main formats: AGM (Absorbed Glass Matt) and Gel Cell (gelified electrolyte).

AGM batteries are superior to traditional flooded technology as they utilise an Absorbed Glass Matt (AGM) process that increases efficiency by lowering internal resistance, resulting in higher capacity. They are also faster to recharge and can be mounted on their side. AGM batteries are commonly used in UPS, alarm systems, telecommunications, golf carts, mobility vehicles, and performance automotive applications.

Gel batteries, on the other hand, have a gelified electrolyte, which is created by mixing sulfuric acid with silica fume. This results in a completely maintenance-free, non-spillable lead acid battery product that does not need to be kept upright. Gel batteries are also more resistant to extreme temperatures, shock, and vibration. They are ideal for applications that require a constant current, such as golf carts, mobility scooters, and power banks.

Deep cycle lead acid batteries are specifically designed for deep cycling applications and contain fewer but thicker plates, resulting in lower max current but a deeper state of charge.

Cranking or engine-starting lead acid batteries have a larger number of thinner plates, resulting in a higher total surface area and higher current potential. These batteries are designed to produce a large burst of current in a short time frame, making them suitable for engine-starting applications.

Marine-specific batteries can be cranking, deep cycle, or a combination of both. They are designed to withstand harsh marine conditions, excessive vibration, and wear, ensuring a longer lifespan.

How to store lead acid batteries in winter

To store lead-acid batteries in winter, you must first perform regular maintenance. This includes watering and removing corrosion. Then, follow these steps:

• Charge the batteries one final time.
• Disconnect the negative cable and wait a few hours before checking the specific gravity or voltage.
• With your hydrometer, check each cell; the specific gravity should be 1.265 - 1.285. Alternatively, you can use a voltmeter to check the voltage; charged batteries should read 12.6V.
• Disconnect the terminals to remove all electrical loads from your batteries.
• Remove the batteries and store them in a cool, dry place where they won't freeze. Ideally, store them on a wooden surface, in a garage or storage facility.
• Use the correct charger for your battery type. Flooded and AGM batteries often require different chargers and algorithms. Smart chargers can help prevent overcharging.
• Trickle-charge the batteries or charge them monthly to prevent self-discharge and extend their lifespan.

By following these steps, you can ensure that your lead-acid batteries are properly stored during the winter and ready for use in the spring.

How to check the charge of a lead acid battery

To check the charge of a lead acid battery, you can use a voltmeter or a hydrometer.

Using a Voltmeter

Using a voltmeter is a quick and easy way to check the charge of your lead acid battery. First, make sure you are wearing protective gear, including gloves and eye protection. Turn on your voltmeter and set it to DC volts. Place the positive probe (red) on the positive terminal of the battery, and the negative probe (black) on the negative terminal. Check the display reading on the voltmeter:

• 12.65 to 12.77 volts indicates a full charge
• 12.45 to 12.54 volts means a 75% charge
• 12.24 to 12.29 volts is 50% charged
• 11.99 to 12.06 volts is 25% charged
• 11.75 to 11.89 volts means the battery is dead

Using a Hydrometer

A hydrometer can be used to check the specific gravity of the electrolyte in an open-cell lead acid battery. This method provides a more rigorous check of the battery's health, but it requires access to the liquid inside the battery. Before using a hydrometer, make sure the battery is fully charged and has been disconnected and allowed to rest for at least 8 hours. Put on protective gear, including gloves and goggles, and remove the caps on top of the battery. Squeeze the bulb of the hydrometer and place the open end into one of the cell openings. Draw liquid into the hydrometer and release it back into the cell three times to acclimate the hydrometer to the temperature of the liquid. Then, draw liquid into the hydrometer and identify the location of the float. Record the specific gravity and temperature measurements, and adjust the specific gravity based on the liquid's temperature. Compare your readings to a depth of discharge (DoD) table to determine the battery's overall health.

Frequently asked questions