What Size Battery Do I Need For My Boat?

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Last Updated on June 21, 2021 by Ellis Gibson (B.Sc. in Mechanical Engineering)

It doesn’t matter whether you want to add or upgrade equipment to your boat or just purchased a new boat.The question remains,’what size battery do I need for my boat?’ you should understand that having an overpowered or underpowered battery in your boat can damage its electronic equipment.

Therefore, there is a need to choose the correct size battery with an actual amount of power for your marine vessel. Try to use this article because it contains a lot of useful information you might need to know concerning your boat’s suitable size battery.

Picking The Right Size

It is advisable to choose a suitable battery size for your boat as per the manufacturer’s recommendations. This remains the first step for the safety of your marine vessel. There are multiple batteries on the market with varying sizes that might confuse you; it’s not easy to make a choice.

Before you make any move, you should understand your boat’s amount of power to function correctly. Knowing the amount of energy will help you pick a battery with your marine vessel’s right size. For that case, boats come with two different battery types that, if not careful with the size, can cause harm to your vessel.

These battery types include; deep cycle and starting battery. A standard model will take only one starting and deep cycle battery, while the duel engines takean extra deep cycle battery.

To determine your boat’s amperage, you will have to use this formula (W=IV), or Watts is equivalent to amperage X voltage. On the other hand, you can determine the amperage hours needed by taking the average amps used per hour.

Therefore, 1.2 amps can be suitable for a 10-watt appliance operating on a 12-volt system.When you turn on the system for 10 hours, it will need 12 amp hours to operate.

Other useful questions that you should ask yourself include;

  • What is the weight of my boat?
  • Am I just trolling?
  • What are some of the accessories that I am powering?
  • Do I have enough space on my boat?

Weight Of The Boat

Based on your boat’s weight or plan to power the boat’s propulsion via the water, you need to get a healthy battery for your vessel. Standardmarine vessels like jons weigh roughly 12 000 pounds with all accessories. This implies that you will need a decent-sized battery; consider 35 and above group size.

Daily Purpose Of The Boat

On the other hand, if you intend to use your boat for trolling around, you will still have to consider your boat’s weight. Honestly, it is unfortunate that you will want to power your boat’s propulsion through this effective way; as an outboard motor. Nonetheless, your boat might be able to move around with electric motoring.

Besides, sometimes you might need to sail on a water body that doesn’t support combustion engines.

Accessories That Needs To Be Powered On The Boat

Furthermore, you might determine your boat’s battery size by considering all the items that need to be powered. For such cases, you will have to consider the exact voltage and amps for your boat battery. Well, mostly 12 volts is always popular, but amps remainan important consideration because they are the fluids running through your boat’s accessories.

The above statement implies that your boat battery’s size depends on the amps it can generate. Therefore, the more accessories and equipment on your boat that needs power, the more energy for their functionality.

You need to understand that we usually measure batteries in amp-hours (AH). With this knowledge, you will know the exact power that your boat requires for its smooth operation. Therefore, you will have to figure out the right AH for your vessel by powering everything on and then measuring the amps flowing from your current battery.

Try also to take current measurement when you power on the engine to determine spikes occurrence. Doing so is very important when picking the correct battery size for your boat.

Based on the minimum, average and maximum amps consumed by your marine vessel when in operation, there is a need to get batteries to display their AH capacity. Take the number of the existing shower and then divide it by your number.

Doing so is significant to come up with a reasonable hour estimation that your boat can be functional. Remember to confirm the average and extremes to know the challenges you might face while out the water.

Available Space On The Boat

The last determination of the size of your boat battery is the existing space on the vessel. Some batteries might be mighty big based on your boat’s size and will probably occupy colossal space. It is advisable to get a bigger battery for your boat, but you still have to consider your boat’s available length.

No one would wish to buy a battery that consumes a lot of unnecessary space on the boat.


To wrap up, you want to ensure that you can get the correct battery size for your boat based on available space, money, and how you plan to use it. Besides, your vessel marine’s energy demand can also answer ‘what size battery do I need for my boat?’.Hopefully, the above report helps you pick the right size battery for your marine vessel.

You need to understand that a wrong-sized battery might damage your boat’s electronic system. Remember, you may also check the manufacturer’s recommendations when buying a battery for your vessel.


How Can I Determine The Size Of My Boat Battery?

Determining your vessel’s battery size is simple; you only need to take the amperage required to power the machine. Other factors that might help you measure your battery’s size battery include; available space on your boat, the number of accessories that need power, etc.

Do I Need A Boat Battery?

Indeed, different boat sizes require different-sized batteries for their operations. A larger boat will always need a bigger battery and vice versa.


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