Storing Batteries With Your Boat: What You Need To Know

Storing boat batteries with your boat during winter is not recommended. While technically allowed, leaving your battery in extreme cold could lead to a cracked case or a completely drained battery if not maintained properly. Even if you do leave the battery installed in the boat, you may need to make several trips to the boat for regular battery maintenance. The best option is to remove the batteries and store them for the winter.

Charging before storage

Charging your boat batteries before storage is essential to ensure they remain functional and do not freeze during the cold months. Here are some detailed instructions on how to charge your boat batteries before storing them:

• Before charging, it is important to perform regular maintenance on your batteries. This includes tasks such as watering and removing corrosion.
• Charge your batteries one final time before storing them for winter. This will ensure that they can be easily recharged next season and reduce the risk of freezing.
• Disconnect the negative cable after charging and wait a few hours before checking the specific gravity or voltage. For lead-acid batteries, the specific gravity should be 1.265 - 1.285, while a voltmeter reading of 12.6V indicates a fully charged battery.
• Disconnect the terminals to remove all electrical loads from your batteries. Even small parasitic loads can slowly drain your battery over the off-season, damaging it.
• Remove the batteries from your boat and store them in a cool, dry place where they won't freeze. Garages or storage facilities with wooden surfaces are recommended.
• Store your batteries in a place with easy access to an outlet for convenient charging.
• Use the correct charger for your battery type. Flooded and AGM batteries often require different chargers and algorithms. Smart chargers can help prevent overcharging.
• Ideally, trickle charge your batteries or charge them monthly to prevent self-discharge and extend their lifespan. Batteries with a full charge are also less likely to freeze.
• If you are using traditional lead-acid batteries, do not leave them without a charge, especially in cold temperatures, as this can cause permanent damage and shorten their lifespan.
• For lithium-ion batteries, store them at a charge of around 40-50%. This will prevent the battery from dropping below 2.50V/cell, which can trigger sleep mode.
• If your batteries are exposed to extremely cold temperatures or are stored for an extended period, they may need to be completely recharged. Bring the batteries to a temperature above freezing before charging to avoid damaging them and reducing their lifespan.

Remember, proper charging and maintenance of your boat batteries during the winter will ensure they are ready for use when the boating season starts again in spring!

Disconnecting the negative cable

It is important to properly store your boat and its batteries during the winter. Both traditional starting batteries and deep-cycle house batteries can be damaged if not properly stored in the winter. One of the steps to winterize your boat batteries is to disconnect the negative cable. Here is a detailed, step-by-step guide on how to do this:

Locate the Battery

First, find the battery in your boat. It is usually located under the hood or in a compartment near the engine.

Disable the Electrical System

Before disconnecting the battery, it is crucial to disable the electrical system to prevent accidental sparks or shorts. Remove the ignition key and set the parking brake.

Locate the Negative Battery Terminal

The negative battery terminal is typically marked with a black or blue symbol.

Loosen the Nut Securing the Negative Battery Cable

Use a wrench or socket to loosen the nut that secures the negative battery cable. Be careful not to touch any metal with the wrench or pliers while loosening the nut. You can use tape to cover the legs of the pliers or use insulated pliers to ensure no short occurs.

Remove the Negative Battery Cable

After loosening the nut, carefully remove the negative battery cable.

Check Gravity/Voltage

Wait for a few hours, and then use a hydrometer to check each cell. The specific gravity should be 1.265 - 1.285. Alternatively, you can use a voltmeter to check the voltage. A fully charged battery should have a reading of 12.6V.

Optional: Install a Battery Disconnect Switch

If you want to add an extra layer of safety, you can install a battery disconnect switch, also known as a battery isolator switch or kill switch. Mount the switch in a secure and accessible location, preferably close to the battery. Connect the negative battery cable to the input terminal of the switch, ensuring a tight and secure connection. Then, attach the output terminal of the switch to a new positive battery cable and run it to the positive battery terminal.

Test the Battery Disconnect Switch

Once the installation is complete, test the switch by turning it to the "OFF" position to verify that the electrical system is disabled. Then, turn it to the "ON" position to restore power.

By following these steps, you can effectively disconnect the negative cable of your boat battery and ensure that it is properly stored during the winter months.

Checking gravity/voltage

Checking the gravity and voltage of your boat's batteries is an important step in maintaining them, especially during the winter. Here's a detailed guide on how to do it:

Checking Specific Gravity:

Specific gravity is used to determine the state of charge of a battery. It is the ratio of the weight of a solution to the weight of an equal volume of water. To check the specific gravity of your boat's batteries, you will need a hydrometer. Here are the steps:

• Disconnect the Battery: Before performing any tests, it is recommended to disconnect the battery, especially if it is on a high rate of charge or discharge.
• Prepare the Hydrometer: Fill and drain the hydrometer 2 to 4 times before taking a sample. This ensures that any previous readings do not affect your results.
• Take a Sample: Carefully remove the vent cap from the battery cell and insert the hydrometer into the cell without pushing down on the top of the plates. Draw the electrolyte into the hydrometer, being careful not to overfill it.
• Obtain a Reading: Look directly at the float in the hydrometer to get your reading. A good hydrometer will be accurate to +/- 0.005 points. For example, a reading of 1.265 could be anywhere from 1.260 to 1.270.
• Repeat for All Cells: Repeat steps 2 to 4 for each cell in the battery to ensure you get readings for all of them.
• Correct for Temperature: Specific gravity readings can be affected by temperature. If the temperature is very cold or hot, use the following equation for correction: Correction factor = (0.331 x Cell Temp ºF - 23) / 1000 or 0.003 pts per 10 ºF.
• Compare Readings: Compare the corrected readings to the manufacturer's specifications. For example, Trojan Battery specifies that the readings should be at or above 1.277 +/- .007.
• Check Voltage if Necessary: If any specific gravity readings are low, it is recommended to also check and record the voltage levels before taking further action.

Checking Voltage:

Checking the voltage of your boat's batteries is another important aspect of maintenance. Here's how you can do it:

• Prepare Your Multimeter: Set your multimeter to voltage. If your multimeter has incremental settings, set it to 20 DC volts. If it does not have incremental settings, simply set it to DC volts.
• Touch the Probes to the Battery Terminals: Touch the red probe to the positive (usually red) terminal and the black probe to the negative (black) terminal. Make sure to match the probe colors to the terminal colors to avoid incorrect readings.
• Take a Reading: Observe the initial reading with the vehicle off. A healthy, fully charged battery should have a resting voltage of around 12.6 volts. If the battery reads 12.2 volts, it is only 50% charged, and below 12 volts, it is considered discharged.
• Compare to Voltage Figures: Compare your readings to standard voltage figures. At about 80 degrees Fahrenheit, a fully charged battery will measure around 12.5 to 12.6 volts. A 75% charged battery will measure closer to 12.45 volts.
• Simulate a Load: If your battery has a reading between 12.3 and 12.5 volts, try charging it to full and then turn on the headlights and the heater blower motor. The voltage should drop slightly but not drastically.
• Perform a Cranking Test: If the car still doesn't start, perform a multimeter test while someone attempts to crank the car. Observe the reading as this happens. A good battery should only drop by about 1 to 1.5 volts during the load and then quickly return to full charge.
• Take Further Action: If the battery shows signs of being bad, remove it and bring it to a specialist for further testing and potential replacement.

Disconnecting terminals

Disconnecting the terminals of your boat's battery is an important step in storing your boat and its battery for the winter. Here are some detailed instructions and considerations for disconnecting your boat's battery terminals:

Safety First:

Before you begin, it's important to prioritise your safety. Put on safety glasses and gloves, and remove any jewellery. Make sure the boat's ignition is off.

Connect Backup Power:

Connect a backup power source to your boat's electrical system. This is crucial, as disconnecting the battery will erase vital data from your boat's computer system. A backup power source will prevent this data loss. You can use a memory saver, which connects via the cigarette lighter or by clamping onto the battery terminals.

Disconnect the Negative Terminal First:

Locate the negative (black) terminal and the positive (red) terminal. First, disconnect the negative terminal. Use a 10-millimetre open-end wrench to loosen the bolt on the negative clamp, then lift it away from the battery. Be careful not to let the wrench touch the positive terminal.

Disconnect the Positive Terminal:

Next, disconnect the positive terminal. Loosen the bolt on the positive clamp, then wrap it in a rag or cloth to avoid accidental contact with the battery or any metal engine components. Lift the positive clamp away from the battery and any nearby metal.

Remove Battery Tie-Downs:

If your battery has tie-downs (long bolts securing a rod over the battery), loosen and remove them.

Lift Out the Battery:

Carefully lift the battery out of the engine compartment. Be cautious not to tip the battery, especially if it's a flooded battery, as you could spill the electrolyte. Boat batteries can be heavy, often weighing 40 pounds or more.

Clean the Battery Compartment:

Once the battery is removed, clean the battery tray, clamps, and battery itself to remove any corrosion. You can use a mixture of baking soda and distilled water for this task.

Do Not Activate Vehicle Systems:

After disconnecting the battery, do not turn on or activate any of the vehicle's systems, as you may drain the backup power source. It's best to leave the boat untouched until you're ready to install a new battery.

Store the Battery Properly:

Store your boat battery in a well-ventilated area, as lead-acid batteries can off-gas even when disconnected. Keep the battery somewhere it won't encounter below-freezing temperatures. You can use a battery maintainer to keep it charged during storage.

Remember, if you're unsure or uncomfortable with any of these steps, it's always best to consult a professional or your local repair shop.

Storing in a cool, dry place

Storing batteries in a cool, dry place is essential for prolonging their lifespan and preventing damage. Extreme temperatures can be detrimental to batteries, with heat causing the fluid in the battery to evaporate, and cold temperatures increasing the likelihood of condensation, which can erode batteries over time.

Therefore, it is recommended to store batteries at room temperature, avoiding areas that are damp, hot, or humid. A garage is a suitable location, as it is shielded from the elements and less prone to temperature fluctuations. Additionally, it is important to keep batteries away from direct sunlight or heat sources, as intense heat can accelerate the evaporation of the battery's fluid.

When storing batteries, it is also crucial to prevent them from coming into contact with metal objects or other batteries. This is because the positive and negative ends of batteries can create a short circuit if they connect, leading to a rapid discharge and potential safety hazards. To avoid this, batteries should be stored in their original packaging or a designated container, ensuring they remain separated and protected.

Another consideration is the accessibility of the storage location. Storing batteries in a place that is easily accessible can make maintenance and charging more convenient. This is particularly important for boat batteries, as they may require regular charging or maintenance during the off-season to ensure they remain operational.

By following these guidelines and storing batteries in a cool, dry place, boat owners can help ensure their batteries remain in optimal condition and extend their lifespan.

Frequently asked questions