How to Charge A Boat Battery On The Water (5 Steps)

Imagine you are having a delightful time on your day out in a lake, in an open sea, or at your favorite fishing spot, and suddenly, your boat battery is dead… Wouldn’t it be unfortunate and fun spoiling?

In the pleasure of your water trek, what you might take for granted is your boat battery. But, in the middle of the amusing voyage, you should at least be aware of charging your boat batteries on the water.

How to charge trolling motor batteries while on Lake?

How to charge trolling motor batteries while on Lake, batteries

Type of Boat Batteries

There are basically two types of boat batteries. A boat might have a single battery with 2 in one performance or double and triple battery systems.

1. Cranking Boat Battery – Cranking batteries are specifically to start your engine and uses thinner lead plates to provide more surface area and store massive amounts of energy for tough starting jobs. The alternator inside will easily replenish the energy used while the motor is running. The way you can check your boat battery chargers is for MCA (Marine Cranking Ampere) levels, which describes the number of amperes a battery can deliver at 0 degrees Fahrenheit and not drop below 7.2 volts.

2. Deep Cycling Boat Battery – These batteries use the energy at a much slower rate and are specially for electrical accessories like GPS, radios, trolling motors, and fish finders, etc. The battery contains few but thin lead plates that can withstand the rigors of several hundred recharge/discharge cycles, which cranking boat batteries can’t. If you use cranking batteries for a trolling motor, it will cause the battery to overheat and fail.

Boat Battery Chargers Used on the Water

There are two types of boat battery chargers that you can choose to charge your boat battery which is as below:

1. Portable Boat Battery Chargers – As the name suggests, they feature portability and can be used in conditions including a low battery in the water. They are less expensive than onboard chargers and hence a popular option in the market today.

They charge the boat battery at a slower pace, and you need to transfer and attach it from battery to battery inside a boat. These boat chargers are helpful in the situation where you can’t install a battery charger like a small boat, a trolling motor-powered kayak, wilderness setting boats, etc.

2. Onboard Battery Chargers – These boat battery chargers are always attached to the battery system in the boat that makes them easy to use. These boat chargers are securely installed and just need to be plugged with the 120-volt power outlet for charging.

The advanced technology in these battery chargers allows multistage charging, and it also charges the boat battery at a fast pace. The technology features longer life, higher capacity, and less loss of electrolytes for your battery.

3. Solar Chargers for Boat – Solar-powered chargers are environment-friendly and less expensive versions of on-the-go battery chargers. They use natural sunlight for a steady power supply to your battery even when it is in use. You can install the solar panel on the roof of your boat, and it works as a great battery maintainer while you are on the water.

Solar chargers use silicon crystals or thin films to use solar energy and generate electricity for your trolling motor battery. It keeps your battery charging even when it is in use.

Also Read: 5 Best Solar Charger for Trolling Motor Battery

These chargers are a reliable source of energy, and you can place them anywhere on your boat as they are lightweight and portable.

Getting Ready to Charge

Now, when we know the right charger to keep with you while you are on a boat, let us understand how to get your battery ready to charge your boat battery on water.

  • Remove any debris or dirt while the battery switch is off.
  • Check the battery connectors and terminals are not dirty.
  • Connections should not be open.
  • Motor plug is mounted properly.
  • The wires are connected properly, as supported by your motor plug.

How to Charge a Boat Battery on The Water

  • Step 1 – Connect your battery to the charger using the extension cord and the motor plug.
  • Step 2 – Connect your trolling motor plug into the power outlet and switch on your battery charger.
  • Step 3 –You need to connect positive wire end to the positive terminal and negative wire end to the negative terminal on the battery with your boat charger.
  • Step 4 – When you choose smart boat battery chargers, you can keep a check on the progress of charging as it goes from the charging stage to the absorb stage and then finally to the storage or float stage.
  • Step 5 – When the LED lights indicate that your battery is charged and comes to a resting voltage, switch off the charger and disconnect it from battery terminals.

How Long should you charge your boat battery?

To deliver the right number of amperes and volts on a regulated basis, the advanced technology for battery charging features below stages:

  • Bulk Stage delivers 75%-80% of the charge, and the amperage could be 10%-15% of the battery capacity.
  • Absorption stage is when the amperage is slowly reduced and controlled when the voltage is already stable, and the battery comes to around 14.1 to 14.8 volts.
  • Storage Stage is when the charging current comes to almost zero as the voltage is around 13.5 to 13.8 volts, which are sufficient to prevent any battery losing.

So, you should charge your boat battery till it reaches storage or floating stage, and in case you use solar chargers, you can keep charging it with an automatic disconnect controller that would off the charging when it is completed.


Digital chargers and Precision chargers are available in a wide range, and you get advanced features such as automatic cut off, temperature compensation, multistage charging, LED indicator lights with the boat batteries charger that makes it easy to use while you are on a water trek or having a pleasurable day out in the sea.

Moreover, a solar panel charger can keep your battery charged to full all the time even when you are draining it. It makes your worries go down, and you can enjoy the fun you are supposed to do rather than worrying about a dead battery while you in the middle of a delightful trolling expedition.

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