When it comes to hitting the open waters, all boat riders want to think about is feeling the breeze through their hair. No one wants to worry about whether their boat will get them safely out and back.
But with a dead boat battery, the boat may not start up at all. Or worse, it could get into the waters only to sputter out before it can return to shore. Not only will that spoil the riders’ day, but it can also be a major liability for boat rental companies. So how can you tell when your boat battery is dying, and what can you do when it is no longer working?
Here’s everything you need to know about boat batteries — from symptoms of a marine battery on its way out to marine battery maintenance.
Symptoms of a Failing Marine Battery
Because boating can be seasonal, your battery may have spent months sitting unused. This can make it tricky to spot the signs of a failing battery. So before anyone ventures too far from the shore, look for these symptoms:
- Slow or no engine turnover. Your boat will likely have no trouble starting up with a newer battery. But as the battery is dying, the engine can take longer and longer to turn over. If it takes more than ten seconds, this is a dying or dead boat battery symptom. A dead battery could also be the culprit if the boat doesn’t start at all. Always seek a professional opinion to ensure it’s not something else, like damaged spark plugs or electrical wires.
- Faulty electronics. Modern boats have a lot of tech integrated for comfort and safety. But if you notice a disruption in the electronics, it could be a sign that the battery is dying. Check your battery if any electronics, from the GPS to the lights, aren’t working.
- Visible damage. Sometimes, you can simply look at a battery and tell something is wrong. A bulging battery indicates acid build-up, while cracking could mean the battery has been overcharging and will lose quality. Either way, the battery will need to be replaced as soon as possible.
Causes of a Spent Boat Battery
Boat batteries can fail for many reasons. Of course, they can naturally reach the end of their useful lifespan, and it will be time to recycle the battery and replace it with a new one. Or, batteries can die prematurely from lack of maintenance or simply sitting unused for too long. If your boat battery is dead, it could be due to the following:
- Corrosion. Over time, corrosion on battery terminals can cause sulfation or a build-up of lead sulfate crystals, which will drain the battery's life. Without regularly inspecting for and cleaning up corrosion, the battery could be vulnerable to sulfation.
- Age. Marine batteries last around 3 or 4 years. Batteries older than that will naturally weaken. If your boat battery shows signs of dying, it may simply be past its prime.
- Parasitic draw. Forgot to turn off the radio or a cabin light? The battery will continue to power anything left on, that is until the battery has died.
- Dormancy. When a boat is left sitting for several weeks or months without use during the off-season, the battery can drain. This is why it’s a good idea to leave your batteries on a trickle charger during the off-season.
What to Do When You Suspect a Dead Boat Battery
If you think your boat battery is dying, there are a few steps you can take to confirm your suspicions. In most cases, if the battery is dead, it’s time to start thinking about a replacement. Boat batteries have a lifespan of about 3 to 4 years, so if it’s been a while since you replaced the battery, it’s likely time for a new one.
Don't Jump the Battery. With car batteries, you can typically jump the engine to give yourself a little more time before replacing the dead battery. But with marine batteries, attempting to jump the engine with a car battery could damage the boat battery and the boat itself.
Many boats have deep cycle batteries, which help power marine tech on the vehicle, but these batteries won’t recharge after you’ve jumped them. They work differently than standard automotive batteries, and therefore can be damaged from attempting to jump.
Check the Battery Voltage. Check the voltage on the marine battery with a battery tester or voltage meter. Marine batteries should have 12.8 voltage with a full state of charge or around 12.4 with the onboard technical components.
If the voltage test shows zero volts, the battery has died. But anything under a 12.4 volt reading should raise some concern, and you may want to start shopping for a replacement battery.
Inspect the Battery. Marine batteries are built to withstand all the bumps and vibrations that come with riding on the water. But boat batteries can still wear out or become damaged. If you think the battery is dead, look for cracking, warping or bulging on the battery, which are clear signs of damage. Any of these signs mean it’s time to replace the battery as soon as possible.
Find a Boat Battery Replacement. A dying marine battery isn’t something to take lightly. While many boats have backup batteries in case of an emergency, no one wants to get caught out on the water with a dead battery. If riders end up stranded or need to be towed back to shore, the boat rental company could be held liable.
If you notice visible damage to the battery, experience symptoms of a dying battery (like slow charging or faulty electronics), or get a poor voltage reading, you should replace the battery before taking the boat out on the water again.
Find the right marine battery for your vehicle fleet, from starting batteries to deep-cycle batteries to dual-purpose batteries to get you from land to sea and back again.
Boat Battery Maintenance
Once you’ve replaced a spent marine battery, you’ll want to give it some TLC to help it last as long as possible and keep riders safe and happy on their rental boats. With proper maintenance, a boat battery can last around up to six years. Follow these steps to keep your boat battery in great condition for years to come:
- Clean corrosion. Corrosion can naturally occur on the battery terminals from the reaction of battery acid and metal. But over time, corrosion can cause sulfation, which can prematurely kill a battery. Make sure to clean off corrosion with a wire brush or with a cloth and a mixture of water and baking soda.
- Maintain a charge. To extend the life of the marine battery, keep the state of charge to at least 50%. You can check the state of charge with a hydrometer or battery tester. Make sure the tester you use is rated to work with the type of battery your boat has, whether it’s flooded, sealed, absorbent glass mat (AGM) or lithium.
- Mind the temperature. Extreme temperature fluctuations or very cold or hot weather can all shorten the life of a battery. Minimize vehicle use in extreme temperatures, and keep the battery stored in a cool, dry place, ideally somewhere that will not experience temperatures much below freezing point.
Maintain a Healthy Battery for Boat Safety
A dead boat battery is a hassle, especially for those who had planned a fun day full of sun and sea. But if the battery is worn out and dies while on the water, it’s more than just an inconvenience — those on board will have to wait to be towed to shore. And the boat rental company is going to be stuck with the bill and probably some bad business reviews.
The best way to keep riders safe and happy is to make sure your boat batteries are in reliable condition. And when it’s finally time for a replacement, find a high-quality marine battery and keep up with maintenance to help it last as long as possible.