Batteries 101

Batteries 101 2018-04-04T15:29:43+00:00

  • Never store a battery in a discharged state.
  • Always recharge your battery after use, especially if it is going to be stored.
  • A fully charged battery should measure 12.7 – 12.8 volts (when disconnected from the charger.)
  • At 12.0 volts, a battery has lost 60% of its capacity and is considered discharged.
  •  Always ensure that the battery capacity is sufficient for the application.
  • Always use the battery for the application for which it was designed.
  • Battery application categories may be loosely classified as follows: automotive, deep cycle, uninterruptible power supply, traction, motive power, renewable energy.
  • For greater life expectancy, do not use automotive batteries in cyclic applications.


  1. Corrosion on battery posts may be removed with a solution of bicarbonate of soda and warm water.
  2. Vented batteries (with filler caps) need to be checked periodically for water levels.
  3. Only top up with de-ionised (distilled) water. It is not advisable to use tap water.
  4. Batteries may need to be given a refresher charge from time to time – especially leisure batteries used in e.g. caravan, boats. Motorcycles, jet ski etc…
  5. Battery voltage should never drop below 12.2 when being stored.
  6. Most modern design batteries, especially sealed batteries require careful charging.
  7. It is advisable to use ‘intelligent’ three stage or multi stage chargers.
  8. Ensure that your battery is held down firmly. Vibration is a battery killer.
  9. Wet acid Batteries in stationary applications may be shaken from time to time to facilitate electrolyte mixing which can enhance the life of the battery.


  • The CCA (cold cranking amp) rating on a battery indicates the amps that can be drawn from the battery at minus 18 degrees Celsiuscontinuously for thirty seconds to an end point voltage of 10.5 volts.
  • The CA (cranking amp) rating on a battery indicates the amps that can be drawn from the battery at Zero degrees Celsius continuously for thirty seconds to an endpoint voltage of 10.5 volts.
  • Reserve capacity indicates the time in minutes that a battery can deliver a load of 25 amps continuously to an endpoint voltage of 10.5 volts.
  • RECHARGING batteries in an AUTOMOTIVE application – a battery in a 12 volt vehicle needs to be recharged at a rate of 13.8 – 14.3 volts. Anything outside this window needs to be checked.
  • RECHARGING batteries with EXTERNAL chargers requires specialised consideration, particularly with sealed batteries.
  • Recharge discharged batteries at a rate of 10% of the rated capacity of the battery as minimum
    (e.g. a 100ah battery should be recharged at a minimum of 10 amps.)
  • Flooded (wet – including sealed) batteries require 8 – 16.0 volts in the equalisation / absorption stage of charging
  • AGM (absorbed glass mat) batteries require 7 volts in the absorption stage charging.
  • GEL batteries require 4 volts in the absorption stage charging.
  • A battery is load tested at three times its ampere hour capacity.
  • The battery must hold this load for 15 seconds and the voltage should not drop below 9.3 volts.
  • Batteries may be left permanently connected to an intelligent charger at a float (trickle) voltage not exceeding 13.6 – 13.8 volts