Electrical power is a key element to ensure the proper functioning of a boat's equipment. Whether for lighting, navigation instruments, engines, or onboard comfort equipment, it is essential to choose the right battery to ensure autonomy and safety. Here is a complete guide to help you choose the marine battery suited to your needs.

1. Understanding Marine Battery Types

Open Lead-Acid Batteries (Wet Cell)

 ✅ Pros: Economical and commonly used, Available in large capacities

❌ Cons: Requires regular maintenance (checking and adding distilled water), Sensitive to vibrations and inclinations

AGM Batteries (Absorbed Glass Mat)

✅ Pros: Maintenance-free, Good vibration resistance, Fast charging

❌ Cons: Higher cost than open lead-acid batteries

Gel Batteries 

✅ Pros: Long lifespan, Ideal for deep discharge cycles, Resistant to extreme temperatures

❌ Cons: Less performant in terms of instantaneous power, Slower charging

Lithium Batteries (LiFePO4)

✅ Pros: Very lightweight, 3 to 5 times longer cycle life than an AGM battery, Ultra-fast charging, Very low self-discharge ❌ Cons: High cost, Requires a specific Battery Management System (BMS)

2. Determining Your Energy Needs

Before buying a battery, it is essential to evaluate your daily electrical consumption. Here are the steps to calculate your energy needs:

• List your electrical equipment (lighting, fridge, navigation instruments, etc.)
• Note their consumption in watts (W)
• Determine their daily usage time (h)
• Use the formula:
  • Capacity needed (Ah) = (Total power in W x Duration in h) / Voltage in V
  • Example: A 60W fridge operating 10h per day at 12V = (60 x 10) / 12 = 50Ah
• Add up all your consumptions to determine the total required capacity.

3. Choosing the Right Capacity and Voltage

• Capacity (Ah): It is recommended to choose a capacity greater than your needs to anticipate unforeseen circumstances.
• Voltage (V): Most boats use 12V, but for more complex systems, 24V or 48V can be found.

4. Starting Battery or Service Battery?

• Starting Battery: Provides high current to start the engine, but does not tolerate deep discharges.
• Service Battery (House Battery): Provides energy to the boat's equipment and is designed to withstand repeated discharges.
• Dual-Purpose Batteries: A compromise between the two, but less performant in each area.

5. Proper Battery Maintenance to Extend Its Lifespan

• Never fully discharge:
  • Lead-acid: Do not go below 50% charge
  • AGM/Gel: Ideally 40% charge minimum
  • Lithium: Can go down to 20%, but regular charging extends its lifespan
• Avoid extreme temperatures:
  • Store the battery in a dry and ventilated place
  • Protect it from temperature variations
• Charge it correctly:
  • Use a charger suitable for the battery type
  • Regularly check connections and terminals

The choice of your marine battery depends on your energy needs, budget, and available space onboard. A good understanding of the different battery types and regular maintenance will ensure optimal use and extended lifespan. Need help choosing your battery? Contact us or visit our store!