BATTERIES

 Battery Types… and their Pro’s and Con’s

There are 4 basic battery chemistries AGM, Gel Cell, Lead Acid and Lithium Batteries and the table below outlines the differences, advantages and disadvantages.

Type

Advantages

Disadvantages

Gel Cell
Batteries
  • Better for rough service environments – Gel protects against the damaging effects of vibration.
  • Maintenance Free
  • Leak proof – Can be installed on its side with small drop in performance
  • Less susceptible to low temperatures
  • When charged correctly does not vent much gas
  • Low self discharge rate
  • Better cycling rates (around 1000 cycles at 50% depth of discharge)
  • New charging voltage ranges now allow you to use any smart charger and can be used for marine applications, motor homes and caravans
  • Higher initial cost than Liquid Cell
  • Electrolyte cannot be replaced if overcharged
  • Not to be used under bonnet as the temperature will heavily reduce the life
  • Not ideal for use with unregulated chargers or alternators
  • Recommended charging with a smart 3 stage charging source

Absorbed Glass Matt
Batteries

(AGM)
  • Maintenance-free
  • Very rapid recharge times, faster than both Gel cell and lead acid batteries
  • Leak proof when tipped or if case is cracked 
  • Can be used for both deep cycle or starting batteries
  • Can be installed at any angle (except upside down)
  • Shock and vibration resistant
  • Minimal gas release when charged properly
  • Low self-discharge rate
  • Can be submerged in water without internal damage (battery terminals will corrode)
  • Many charge cycles when properly charged
  • Better performance for DC loads
  • Higher initial cost than Liquid Cell
  • More weight per Ah than wet cells
  • Electrolyte cannot be replaced if overcharged
  • Recommended charging with a smart 3 stage charging source

Flooded
Lead Acid
Batteries

(FLA)
  • Lowest cost to purchase by amp hour
  • Less sensitive than the other two styles in accepting higher charging voltages and less expensive / less regulated charging methods 
  • Good deep cycle performance or starting performance… BUT NOT BOTH
  • Can spill corrosive battery acid
  • Must be installed upright
  • Requires regular maintenance 
  • More quickly damaged if left discharged
  • NB: All lead acid batteries sulphate if left discharged and require maintenance charging
  • Not suitable for high vibration environments

Lithium
Batteries

(LiFePO4)
  • Light weight V’s Amps delivered (Energy density)
  • Best system for cyclic applications
  • Low self discharge rate
  • Best depth of discharge (DOD)
  • Highest number of cycles over life of battery
  • Fast charge and discharge rate
  • Low maintenance
  • High initial cost
  • Requires battery management system (BMS)
  • Require specialised charging regime

 

 

 

The type of battery is important as well, and they are broken into three categories. It is important to note that it is damaging for a battery to be used for the wrong purpose.

–     Starting Batteries – have very high CCA’s (cold cranking amps) and are designed to deliver very high amperage for a short period of time for providing power to things like starter motors or bow thrusters. They are not recommended for deep cycle applications. Usage such as this will kill the battery in a short period of time. Should not be heavily discharged.

–     Deep Cycle or House Batteries – have thick lead plates and designed to deliver low amperage over long periods of time to run things like pumps, lights, electronics fridges and inverters. Designed to be discharged and re-charged repeatedly.

      Marine Batteries (Dual Purpose) – is a loosely used description, however, the marine battery can be best described as a hybrid battery or a blend between a start battery and a deep cycle battery. It does both functions, but has some compromise of start or deep cycle functions. They are commonly used on trailer boats and smaller sport cruisers due to their dual application capability where space is normally at a premium.