Battery Size for 90 HP Johnson Outboard: Choose the Right One


battery size for 90 hp johnson outboard
battery size for 90 hp johnson outboard


When it comes to powering your 90 HP Johnson outboard motor, selecting the correct battery size is crucial for optimal performance and longevity. A well-matched battery ensures your outboard starts reliably, powers your accessories, and provides peace of mind during your boating adventures. In this article, we’ll explore the factors to consider when determining the appropriate battery size for 90 HP Johnson outboard motor.

Battery Types

There are primarily two types of batteries suitable for powering outboard motors: starting batteries and deep cycle batteries. Each serves a distinct purpose, and understanding their differences is essential when choosing the right battery size.

  • Starting Batteries: These batteries are designed to deliver short bursts of high cranking power to start the engine. They are not intended for continuous use and are best suited for outboard motors that require frequent starts and stops.
  • Deep Cycle Batteries: Deep cycle batteries, on the other hand, are designed to provide a steady and sustained source of power over extended periods. They are ideal for running accessories like trolling motors, fish finders, and navigation systems. Deep cycle batteries are a better choice if you plan to use your 90 HP Johnson outboard motor for longer durations or run various electronics simultaneously.

Battery Size and Capacity

When determining the appropriate battery size for 90 HP Johnson outboard motor, you’ll need to consider both physical dimensions and electrical capacity.

  • Physical Dimensions: Ensure the battery you choose fits comfortably within the designated battery compartment on your boat. Battery group sizes, such as Group 24, Group 27, or Group 31, indicate the physical dimensions of the battery. Measure the available space on your boat to select a battery that fits snugly.
  • Electrical Capacity: The electrical capacity of a battery is typically measured in ampere-hours (Ah) or reserve capacity (RC). For starting batteries, look for a high cranking amp (CA) rating, while deep cycle batteries should have a higher ampere-hour rating. The ideal capacity depends on your specific boating needs. As a general guideline, aim for a battery with at least 800 CCA (cold cranking amps) for reliable starting power.

Dual-Purpose Batteries

In some cases, boaters may opt for dual-purpose batteries that provide a balance between starting power and deep cycling capabilities. These batteries are a good choice if you want a single battery to handle both starting the engine and powering accessories. However, they may not excel in either category when compared to dedicated starting or deep cycle batteries.

Consult Your Outboard’s Manual

The manufacturer’s recommendations are always a reliable source of information when it comes to selecting the right battery size for your 90 HP Johnson outboard motor. Review your outboard’s owner’s manual or consult the manufacturer’s website for specific battery requirements and guidelines. Following these recommendations ensures compatibility and optimal performance.

Maintenance and Charging

Proper battery maintenance is essential to prolong its lifespan and ensure consistent performance. Regularly inspect and clean the battery terminals, check the water level in lead-acid batteries, and keep the battery charged when not in use. Investing in a quality marine battery charger can help maintain your battery’s health and prevent premature failure.


Selecting the right battery size for your 90 HP Johnson outboard motor is a critical decision that can greatly impact your boating experience. Consider the type of battery, physical dimensions, electrical capacity, and consult your outboard’s manual for guidance. Whether you need a dedicated starting battery, deep cycle battery, or a dual-purpose battery, choosing the correct size ensures that your outboard motor performs reliably and efficiently, allowing you to enjoy your time on the water with confidence.

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