Boat Operation: What Happens When Batteries Die?

A dead boat battery can be a nightmare for boat riders and rental companies alike. Not only does it spoil the fun, but it can also be a safety hazard if the boat gets stranded in the middle of the water. While boat batteries typically last anywhere from 2 to 10 years, depending on the type and maintenance, a dead battery can cause the boat engine to sputter out and die, leaving riders with no choice but to wait for a tow back to shore. In this article, we will explore the factors that contribute to boat battery death and provide tips on maintenance and replacement to ensure a safe and enjoyable boating experience.

What to do if your boat battery is dying

A dead boat battery can be a huge inconvenience, and even a safety hazard, so it's important to know what to do if you suspect your boat battery is dying. Here are some detailed instructions to help you handle this situation:

Signs of a Dying Battery:

Before heading out on the water, keep an eye out for these warning signs:

• Slow or no engine turnover: If it's taking longer than usual for your engine to turn over, or it's not starting at all, it could be a sign of a dying battery.
• Faulty electronics: Disruptions in modern boats' tech and electronics, such as GPS or lights not working, could indicate battery issues.
• Visible damage: Look for any bulging, cracking, warping, or leaking, which could be due to acid build-up or overcharging.

If you notice any of the above signs, take the following steps:

• Don't jump-start the battery: Unlike car batteries, marine batteries, especially deep cycle batteries, can be damaged by jump-starting.
• Check the battery voltage: Use a battery tester or voltage meter to check the voltage. If it's below 12.4 volts, it's time to consider a replacement.
• Inspect the battery: Look for any physical damage, such as cracking or bulging, which could indicate the need for an immediate replacement.
• Consider a replacement: Boat batteries typically last 3 to 4 years. If yours is within this range or showing signs of dying, start looking for a suitable replacement.
• Maintain the battery: To extend the life of your battery, regularly clean off corrosion, maintain a charge of at least 50%, and store it in a cool, dry place to avoid extreme temperature fluctuations.
• Troubleshoot the issue: If your battery is draining too quickly, you may need to identify and fix any parasitic draws, such as electronics that remain on even when the boat is turned off.

How to identify a parasitic draw

A parasitic draw is a type of electrical current drain that occurs in a vehicle when the ignition is turned off. It is important to identify and fix the cause of a parasitic draw to prevent damage to the battery and ensure the vehicle starts properly. Here are some steps to identify a parasitic draw:

• Start with a fully charged battery. You could get inconsistent or inaccurate results if the battery isn’t charged.
• Set up your equipment. Connect the red lead of the multimeter to the negative cable end of the battery and the black lead to the battery terminal. Then, disconnect the cable without breaking the bridge’s connection.
• Turn off all electrical components, including the radio, headlights, interior lights, and other electronics. Wait for the vehicle’s computer modules to go to ‘sleep’, which normally takes 10 to 15 minutes but can take up to an hour or more.
• Measure the current draw. Look at the multimeter and note the current draw. For newer cars, a reading between 50 milliamps (mA) and 85 mA is considered normal. If you have a higher draw, particularly over 100 mA, try to track down the source of the draw and fix it.
• To locate the source of the parasitic draw, start pulling fuses and removing relays one by one until the draw goes away. Once the draw disappears, you’ve likely found the issue.
• Now, trace the circuit for the short or identify if the part has an internal problem. You can start by replacing the part with a known good one before cutting any wiring looms open.

Identifying and correcting a parasitic draw can be tricky and time-consuming, but following these steps will help you resolve the issue and prevent further damage to your vehicle's battery.

How to store your boat battery

End-of-Season Maintenance

Before storing your boat battery for the winter, perform end-of-season maintenance. Inspect the cables, connections, and battery case for any dirt or corrosion. Remove any corrosion on the battery terminals with a wire brush or a cloth and a mixture of water and baking soda.

Final Charge

Give the battery a final charge before storing it for the winter. This will help ensure the life and capacity of the battery and prevent it from freezing in cold temperatures.

Check State of Charge (SOC)

Use a hydrometer to check each cell of a conventional flooded lead-acid battery, confirming a specific gravity of 1.265–1.285. Alternatively, you can use a voltmeter to check the voltage; a reading of 12.6V indicates a fully charged flooded battery. For an Absorbed Glass Mat (AGM) battery, a full charge will read 12.9V or higher.

Disconnect the Battery Cables

Disconnect the battery cables to prevent parasitic draw from any electronics that remain connected. Even a small power draw can drain the battery in a short period.

Remove and Store the Battery

Remove the battery from the vessel and store it in a cool, dry location where it won't be exposed to freezing temperatures. If using a conventional lead-acid battery, store it in a plastic bin or on a surface that won't react with acid in case of leakage or damage. Ensure the storage area has easy access to an outlet for charging.

Maintenance Charging

Consider using a trickle charger or a smart charger to maintain the battery charge and prevent overcharging. Charge the battery monthly or keep it connected to a trickle charger. Use a charger designed for your specific battery type, as chargers are not universal.

Lithium Battery Maintenance

If you have a lithium battery, less maintenance is required during the off-season. Store the battery at around 50% charge and check it every few months. If the charge drops below 30%, connect it to a charger and recharge it to 50%.

Battery Type and Charger Compatibility

Use a charger that is compatible with your battery type (lithium, flooded, AGM, etc.). Many new chargers work with multiple battery types, but not all, so always check the specifications. Additionally, use a charger designed for your battery's voltage (6-volt, 12-volt, etc.).

How to clean your boat battery

Safety First

Wash your hands and put on protective gloves and goggles. You'll be working with a combination of lead and acid, so it's important to protect your skin and eyes from any splashes.

Step 1: Turn Off the Power

Before you start cleaning, make sure all switches are turned off and the engine is completely shut down. This is important to avoid any electrical shocks or damage.

Step 2: Disconnect the Cables

Loosen and disconnect the negative cable first (it's usually black with a negative symbol). Then remove the positive cable (red with a positive symbol). Always disconnect the cables in this order to avoid any sparks.

Step 3: Inspect the Battery

Check the battery terminals for any signs of corrosion or dirt. Corrosion looks like a powdery blue or white substance, while dirt appears as a dark, dusty film.

Step 4: Clean the Terminals

Use a wire brush or battery terminal cleaner to remove any corrosion or dirt. If using a wire brush, dip it into a mixture of baking soda and water, then scrub the terminals. If using a battery terminal cleaner, apply it to the affected area and let it sit for a few minutes to dissolve the buildup.

Step 5: Rinse and Dry

After scrubbing or applying the cleaner, rinse the terminals with clean water and wipe them dry with a clean towel.

Step 6: Apply Petroleum Jelly

Before reconnecting the cables, coat the terminals and cable connectors with a thin layer of petroleum jelly (Vaseline). This will help prevent the accumulation of corrosion.

Step 7: Reconnect the Cables

Reconnect the cables, starting with the positive cable first, followed by the negative cable. Tighten them securely to ensure a good connection.

Maintenance Tips

• Clean your boat battery at least twice a year (spring and fall).
• During the summer, tighten your battery terminals once a month to prevent losing the connection.
• If you have a flooded battery, maintain its water level with distilled water. Do not use tap water as it can cause calcium sulfation.
• Lightly grease the terminals with dielectric grease to prevent electrical problems and corrosion.
• Ensure your battery is seated properly in the battery compartment to avoid sliding or bouncing during jerky movements.
• Keep your battery charged.

How to charge your boat battery

Knowing how to charge your boat battery is an essential skill for every boater. Here is a step-by-step guide to charging your boat battery:

Choose the Right Charger

There are many different types of boat batteries, so you will need to select a charger that is designed for your specific battery. Match your charger to your boat battery's chemistry and voltage. If you have more than one battery on board, ensure the charger is compatible with both.

Boat battery chargers fall into two categories: onboard and portable. Onboard chargers are permanently installed and connected to the battery system, while portable chargers are known for their convenience and affordability.

Select the Right Time

Charging a boat battery requires optimal conditions. The ideal temperature for charging ionic lithium batteries is above freezing, but you can also charge them at temperatures as low as -13°F without causing damage.

Clean the Battery Terminals

Grimy battery terminals can disrupt the charging process, so it is important to clean them before you begin charging.

Connect the Battery Charger

To connect the charger:

• Attach the red (positive) cable to the red terminal.
• Attach the black (negative) cable to the black terminal.
• Plug in the charger and turn it on.

If you are using a smart charger, you can leave it to charge without monitoring, as it will automatically stop charging when it is done. However, if you are using a lead-acid charger, you will need to manually disconnect it once the battery is fully charged.

Disconnect the Charger

Once the battery is fully charged, simply reverse the connection process. First, unplug the charger, then remove the black cable, followed by the red cable.

Additional Tips:

• Always keep your battery fully charged to avoid sulfation, which occurs when a lead-acid battery remains partially charged for extended periods.
• Regularly check the battery's state of charge, electrolyte levels, and the condition of the terminal connections.
• Clean corroded terminals and ensure they are tight.
• If your boat will be unused for a long period, consider using a battery maintainer or trickle charger to keep the battery in good condition.
• Store batteries in a cool, dry place.
• Follow the manufacturer's instructions for charging and maintenance.

By following these steps and tips, you can ensure your boat battery stays charged and healthy, providing reliable power for your boating adventures.

Frequently asked questions