Easy Ways To Deal With A Dead Boat Battery: Newbie Guide


It happens to all of us. You hop in your boat, turn the ignition key on, and the boat engine makes a sluggish sound before dying — or maybe it doesn’t start at all. Why? The battery is dead. Here’s what to do next.

The most common and easy way to deal with a dead boat battery is by jump-starting it. All you need is a set of jumper cables and a functional battery, OR it could become very handy if you have a jump starter. Also, keep in mind that you shouldn’t try to jump-start a boat if its battery is damaged.

Maybe you accidentally left the electronics onboard turned on or left the boat for a long time and forgot to disconnect or remove the battery. Typically, a dead battery means calling for help. But there are ways you can deal with a dead battery on your own with a little knowledge.

You face one of three scenarios here. After jump-starting the boat. Ideally, it may work well. Second, sometimes, the battery may not hold the charge due to a bad cell, or the battery itself is bad, requiring you to jump-start it each time for it to work. Third, you won’t be able to charge it at all.

Related post – How To Tell If Boat Battery Is Bad? Check this article to know more about the symptoms of a bad boat battery so that you can take the necessary actions prior.

What To Do If Boat Battery Dies?

There are four ways to deal with a dead boat battery. Choose the method that fills your needs.

  1. Jump-Start your boat with a spare battery alone.
  2. Jump-Start your boat with a battery from another boat or car directly.
  3. Take the battery out of the boat and use it after fully charging it.
  4. Use a Jump Starter to start your boat.

It’s a good idea to buy a set of jumper cables and keep them in your boat. If you don’t have jumper cables on board, you have to find someone who has jumper cables around wherever you are there at that time.

Related post – How To Test The Boat Battery Working Condition? Check this article to know more about the testing (voltage and load testing) of the battery and to determine immediately whether the boat battery is working or not.

Jump-Start Your Boat With A Spare Battery Alone

  • Connect Both The Battery Terminals Properly. Connect the negative (black) jumper wire to the dead battery’s negative terminal and the good battery’s negative terminal. Similarly, connect the positive (red) jumper wire to the dead battery’s positive terminal and the good battery’s positive terminal.
  • Start The Boat. If the spare battery is in good condition, it will immediately start the battery. And you can remove the jumper wires right away if the boat starts since your alternator will charge the battery from then on.

Jump-Start Your Boat With A Battery From Another Boat Or Car Directly

  • Connect Both The Battery Terminals Properly. Connect the negative (black) jumper wire to the dead battery’s negative terminal and the good battery’s negative terminal on the battery of your friend’s boat or car. Similarly, connect the positive (red) jumper wires.
  • Start Your Friend’s Boat Or Car, and don’t start your boat. Now, you should start your friend’s boat or car since now you are not using a spare battery that is connected to your boat alone; you are using another boat’s or car’s battery. If the other battery is in good condition, it will immediately start charging your battery.
  • Wait Around 15 Minutes For The Battery To Charge Partially. After 15 minutes, remove the jumper cables and start your boat. It will start your boat and again wait for another 15 minutes to fully charge your battery with the boat alternator’s help.

Take The Battery Out Of The Boat And Use It After Fully Charging It

  • Disconnect all the wires and remove the battery from your boat. Locate the battery on your boat and remove all the wires that are connected to the battery and remove the battery off the boat.
  • Charge the battery. After removing the battery from the boat, charge the battery fully.
  • Place the battery back in the boat. Connect all the connections as it was and start your boat. It will start the boat unless if the battery is bad or need a replacement.

Use A Jump Starter To Start Your Boat

Probably this is the easy way to deal with a dead boat battery. Jumpstarters are portable battery devices that allow for jump-starting of boats and other vehicles. These devices operate similar to jumper cables but do not require an additional vehicle to provide the power needed to boost the dead boat battery.

  • Connect the jump starter with the battery. Connect the negative (black) jumper wire from the jump starter to the dead battery’s negative terminal. Similarly, connect the positive (red) jumper wire from the jump starter to the dead battery’s positive terminal.
  • Start the boat. It will start the boat, and you can remove the jump starter cables right away if the boat starts since your alternator will charge the battery from then on.

If your boat didn’t start even after trying those methods, check the connections and try again; if still no, either there is a problem with your battery, or it has something to with your outboard itself or others.

Related post – Boat won’t start and just clicks? Check this article to know all the reasons why the boat won’t start, and clicks along with a detailed solution.

Some Of The Easy Ways To Increase Your Boat’s Battery Life

There are some simple ways to improve your boat’s battery life. By doing them, your battery could last 7-10 years in total. We will now see how to increase your boat’s battery life.

Don’t Deeply Discharge A Boat Battery

Discharging a boat battery deeply often (75% or 50% or less) will decrease the battery’s total number of cycles dramatically. When a boat battery has been subjected to deep discharge, the amount of electricity that has been discharged is actually 1.5 to 2.0 times as great as the battery’s rated capacity.

One more thing to consider is a battery that has been deeply discharged takes a longer time to charge it fully (100%) than a normally discharged battery (not deeply). The occasional dip to 75% or 50% DOD (Depth of Discharge) is fine, but you need to try to recharge it up with 100% ASAP.

Generally, 50% is the max recommended DOD by most all AGM & flooded battery manufacturers. So, make sure you won’t get below that quite often. The less deep discharge you regularly go, the more number cycles you will get, which implies more life (years).

Fully Charge And Disconnect Them During A Long Term Storage

Fully charging a boat battery (100%) before storing it away for any long-term storage or winter is crucial. Any battery will self-discharge over time, and you can’t stop it from happening that. If it is not fully charged, it will hurt the battery’s life eventually, and it could die quickly.

And another thing to consider here is disconnecting the battery during the winter or long-term storage is crucial. If a battery is not disconnected, all the electrical devices onboard will slowly discharge the battery over time, even if they are turned off. So, disconnecting the boat battery during long-term storage is essential.

So, pull them out for winter storage, and keep them in the garage on a wood platform or a rubber platform for most of the winter. Or just disconnect them and leave them on a boat but charge them fully before leaving and using them.

Don’t Leave A Battery On A Charger Continuously

Charging a battery is essential, but overcharging it will kill the battery over time. This is one of the main reasons why the flooded battery will bulge outside. Overcharging a battery causes excessive gassing — the electrolyte gets hot, and both hydrogen and oxygen gas are generated.

On older vented batteries, the electrolyte could cook away, leaving the plates exposed and ruining them. On sealed batteries, the buildup of gases could cause the battery to burst. Even if you leave the charger connected continuously, at a small 2 amps, the battery eventually will die.

So, don’t put your battery on the trickle charge or any charger continuously. Many chargers are not as “smart” as they claim. Charge to full, then disconnect is often safer. Float or maintenance chargers such as a Battery Tender keep the battery charged without the risk of damage.

Don’t Keep A Battery In Hot Places

The temperature will affect the boat battery most because high temperatures will not only be a loss of battery capacity but also leaks or ruptures the battery as well. Store your batteries at room temperature or below. The recommended storage temperature for most batteries is 59 °F (15 °C) (source).

As temperatures increase, especially over 100 °F (38 °C), so does your batteries’ internal discharge. If a new fully charged battery is left sitting 24 hours a day at 110 °F for a month, it would most likely not start an engine. Cold weather isn’t nearly as hard on batteries as hot weather.

The chemistry just does not make the same amount of energy in bad conditions. A deeply discharged battery can freeze solid in sub-zero weather. So, store your batteries well during extreme winter and hot summers to avoid any problems.

Fully Charge A Battery As Often As Possible

While using your boat every day, the battery discharges. Fully charging the battery will improve the number of cycles. However, the number of cycles won’t increase beyond the manufactures max cycle count. Using a battery at lower DOD (50% and less) will damage the battery and puts more load than a fully charged battery.

It will eventually degrade the battery’s life if it is used while deeply discharged. Weekly or biweekly, getting your battery up to 100% as a minimum guideline will dramatically improve cycle life. So, charge it as often as possible, but ensure to charge it fully weekly or biweekly.

It’s OK to use a battery between 50% or 60% DOD and 80% or 90% DOD while cruising. But then try to get a good full 100% overnight charge at least once or twice a week.

Check Electrolyte Regularly On Flooded Batteries

Whenever you are working with a battery, you’ll want to take some safety precautions. Not only can the battery give you quite a shock, but it can also become dangerous if not handled properly. Ensure you have gloves and safety goggles and disconnect the battery before you start messing around with it.

First, clean the battery with a brush and a mixture of baking soda and water near the terminals and top. Then remove the plastic tops covering the cell ports with the help of a screwdriver or any. Once the covers have been removed, carefully clean away any dirt that may have built up underneath.

Now check the electrolyte levels inside each cell and add only the distilled water, not any other water form if electrolytes are not up to the level. A common rule of thumb is to add enough water to cover the electrodes or plates. Then cover the cell ports and charge it fully and then test whether it is working properly or not.

The Key Takeaways

The most common and easy way to deal with a dead boat battery is by jump-starting it. All you need is a set of jumper cables and a functional battery, OR it could become very handy if you have a jump starter. Also, keep in mind that you shouldn’t try to jump-start a boat if its battery is damaged.

There are four ways to deal with a dead boat battery. Choose the method that fills your needs.

  1. Jump-Start your boat with a spare battery alone.
  2. Jump-Start your boat with a battery from another boat or car directly.
  3. Take the battery out of the boat and use it after fully charging it.
  4. Use a Jump Starter to start your boat.

If your boat didn’t start even after trying those methods, check the connections and try again; if still no, either there is a problem with your battery, or it has something to with your outboard itself or others.

Mahidhar

My name is Mahidhar, and I am passionate about boating. Every day I learn some new things about boats and share them here on the site.

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