Types Of Marine Batteries

Marine batteries are mainly made for use on boats.Basic automobile batteries can also be used for marine operations, but are not recommended, This is because of three main reasons; firstly because most automobile batteries are cranking batteries that draw out large amounts of charge quickly,while boats need a steady charge for operating trolling motors, secondly because automobile batteries have only two terminals, while marine batteries come with extra terminals for screwing in wires to, and finally, boats do not have good suspension built in, so they need thicker, robust battery packs for operating boats. For boats, a combination of cranking batteries for starting, powering operations and accessories, and deep cycle batteries for long term operation of trolling motors and powering instruments like depth finder, and fish locators.

Cranking batteries

A cranking battery is a rechargeable battery that provides electric power to an engine and luther electrical systems. These batteries usually provide starting power to the engine, and also power it during it’s operations, along with some accessories, like lamps and motors for reeling in fish nets. A good rule of thumb is  that any instrument that needs large amounts of power for shorter durations, will be powered by a starting battery.

Pros:

  • These batteries provide a large amount of charge in a short period of time
  • These batteries can be charged by the engine alternator

Cons:

  • These batteries do not maintain constant charge output
  • A full discharge generally reduces their lifespan

Deep cycle batteries

These batteries are designed to withstand constant discharge for sustained periods of time. These batteries can withstand several hundred charging and discharging cycles. It is used for trolling motors and accessories like depth finder and fish locators, or onboard lighting and sound systems

Pros:

  • These batteries are good for constant use
  • Deep cycle batteries are also designed for deeper discharges. Deep discharge batteries can be discharged upto 100%
  • Deep cycle batteries can also be used for a large number of charge-discharge cycles

Cons:

  • These batteries cannot provide a sudden, large charge

Dual purpose batteries

A dual purpose battery can be used for both starting and deep cycle purposes, though they do not work as well as separate batteries. They are preferred by smaller boats

Types of batteries on the basis of composition

The most popular types of batteries based on their composition are:

  1. Flooded batteries:

Flooded batteries are the most traditional battery type, and contain a sulfuric acid and distilled water electrolyte, with lead and lead oxide terminals. This wet electrolyte based battery is inexpensive and easy to use, but needs regular maintenance and topping up

Pros:

  • Suitable for long term power back up
  • These batteries are relatively inexpensive
  • These batteries survive hundreds to thousands of charge and discharge cycles, provided regular maintenance

Cons:

  • These batteries need to be regularly maintained and inspected
  • These batteries can be damaged by impact, and leaked acid is corrosive in nature
  • Gel type batteries:

A gel type battery has a silica based gel like electrolyte, instead of a liquid acid based one as in flooded batteries.This electrolyte is more stable, and thus can be used in small, confined spaces, because of no outgassing, and also bear severe vibrations. 

Pros:

  • These batteries have no outgassing
  • These batteries do not have liquid in them, and are spill resistant
  • These batteries are vibration resistant

Cons:

  • Sensitive to overcharging and undercharging, and need specific chargers for charging
  • These batteries have a slow charging cycle
  • AGM type batteries:

AGM batteries have a mat that carries the electrolyte between terminals.The dry electrolyte is stored in a separate compartment, and is carried between the terminals through the mat. The mat acts as the path through which the charge flows through the battery

Pros:

  • These batteries have no outgassing
  • These batteries do not have liquid in them, and are spill resistant
  • These batteries are vibration resistant
  • These batteries are extremely low maintenance

Cons:

  • Sensitive to overcharging and undercharging, and need specific chargers for charging
  • These batteries have a depth of discharge of only 50%
  • Lithium-ion batteries:

Lithium ion batteries are a relatively newer type of batteries. They are extremely energy dense, and retain charge, often at the same charge level as left at. These batteries also produce a really high current, and can drive larger machinery easily. However, the main challenge with this type of battery is the costs associated with buying them

Pros:

  • These batteries can provide charge at any level required
  • These batteries sustain a constant voltage
  • These batteries provide 3 to 4 times the energy of conventional batteries at a significantly lower weight and size
  • These batteries can sustain deep discharges upto 99.9%

Cons:

  • The materials, and the battery is expensive
  • These batteries need their individual cells equally charged

Final words

In this article, we have discussed different types of batteries for marine applications, and compared uses of cranking batteries, deep cycle batteries, and dual purpose batteries. Also, we discussed different types of batteries on the basis of chemical composition and their pros and cons. We hope you found this article useful.

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