How to Keep Marine Batteries from Corroding

February 21, 2023

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Summer’s fast approaching, and now’s the time to get your fleet of marine craft ready for a new season on the water. Keep your craft — and the batteries that power them — in top shape to ensure a safe and fun year for all your sea-loving customers. 

Marine batteries are designed to withstand harsh marine environments and provide reliable power for starting engines, running electronics and providing auxiliary power. Features like heavy-duty, vibration-resistant construction and water-resistant casing can ensure reliable performance in marine applications. 

Even so, marine batteries are not immune to corrosion. Marine conditions, like high humidity and saltwater exposure, can make corrosion more likely. This post will discuss the following: 

  • Recognizing the signs of marine battery corrosion
  • How to prevent marine battery corrosion
  • The consequences of ignoring corrosion 
  • Signs that you need a new battery

What Is Battery Corrosion? 

Battery corrosion refers to the oxidation of metal terminals on the surface of a battery, causing it to produce a greenish or white powdery buildup. Corrosion happens when the electrolyte (sulfuric acid) releases hydrogen gas. 

As hydrogen gas collides with the air and moisture, the chemical reaction causes corrosion. This can occur when the battery is damaged, overcharged or stored improperly for an extended time, and it can affect the performance and overall lifespan of the battery. 

How to Prevent Marine Battery Corrosion

Marine batteries are built tough to power your craft even in rough waters. However, being constantly exposed to the harsh conditions and corrosive elements of marine environments makes them more susceptible to corrosion. Corrosion can cause battery terminals and connections to become clogged and reduce performance, eventually leading to battery failure. 

Proper battery maintenance will extend the life of your marine batteries and help you avoid costly battery replacements and unexpected breakdowns on the water.

Use this as a checklist for staff as you prepare your fleet for the boating season: 

Clean battery terminals and connections. Before sending a boat out on the water, it is essential to clean the battery terminals and connections with a wire brush to remove any dirt or debris. Do this at the start of each season. 

Prevent further corrosion. After cleaning, apply an anti-corrosion spray or terminal protector to provide an added barrier against corrosion. This is particularly important for boats in saltwater environments, as salt can exacerbate the corrosive effects of moisture and other elements.

Check your connections. Tight battery terminal connections can help prevent corrosion. In addition, some boaters use anti-corrosion pads made of fiber between the terminals and cables to provide one more barrier to corrosion. 

Practice proper charging habits. Overcharging your marine batteries can lead to increased hydrogen gas production, contributing to corrosion. Therefore, it is essential to properly maintain the battery's state of charge using a charger that meets the manufacturer's specifications to prevent corrosion and ensure that your batteries have sufficient power while out on the water.

Keep batteries clean and dry. Check batteries about every four to six months and before placing batteries in storage at the end of the season. Clean away any corrosion, dirt or debris that may have built up around the battery terminals. 

Store smart. At the end of the season, or whenever a battery will sit unused for an extended period, store marine batteries in a cool, dry and well-ventilated place, away from salt water, freezing temps and excess humidity. 

Consequences of Ignoring Corrosion

Nobody wants a dead battery, least of all when they’re bobbing in the middle of the ocean. Ignoring signs of corrosion can reduce a marine battery’s performance. If it’s left to build up, corrosion on the battery terminals can disrupt the flow of electricity, reducing the battery's ability to hold a charge and causing the battery to short out when you need it the most. 

Corrosion can also cause permanent damage to the battery, leading to a reduced lifespan and the need for more frequent replacement. 

How to Clean a Corroded Marine Battery

If you see signs of corrosion, such as white powdery residue or discoloration around the terminals, clean the terminals and connections with a baking powder and water solution to neutralize the acid. Once the battery has been cleaned, it is important to rinse it thoroughly with clean water and dry it completely before applying a protective spray or coating to the terminals. 

Remember that corrosion can extend to the cables and may not always be visible. Inspect the wires and connection points thoroughly to ensure the corrosion hasn’t spread, then monitor the battery's performance closely.

Signs it’s Time to Replace Your Marine Battery

Marine batteries have a lifespan of about three to four years, potentially up to six, depending on maintenance and usage. Eventually, you’ll need to replace them. Here are a few signs that it’s time to install a new battery on your boat.

  • Weak starter performance. If your battery can barely turn the starter over when starting your outboard engine, it's a sign that the battery has lost its power and needs to be replaced.
  • Dimming lights and electronics. If your boat's lighting and electronics dim or even go out when starting your engine, it could indicate a problem with your battery, and it's time to replace it.
  • Poor battery charge retention. If your battery will not hold a charge, it's time to replace it.
  • Submerged battery. If your battery ever becomes submerged in water, it's likely damaged and needs to be replaced.
  • Frequent discharging. If your battery frequently discharges between use, it's a sign that it is failing and needs to be replaced.

Marine batteries are designed to withstand harsh marine environments but are still susceptible to corrosion. Understanding how corrosion can develop, how to prevent and clean it, and how to spot signs of deeper battery troubles can ensure your craft is fit to offer clients year after year of boating fun.