Ah – The first number you will see is the Amp hours of the battery or Ah. Amp hour is a measure of battery capacity or how much energy can be stored in it, the higher the number the more it can store.
The most common numbers are 75Ah, 85Ah, 100Ah and 110Ah. This figure comes from a rating test called the C20 standard, it takes a fully charged battery, say a 100Ah rated battery, divide 100 by 20 = 5. This battery could deliver 5 amps of power for 20 hours until the battery voltage drops below 10.5volts. If a 60Ah rated battery is used it would be 60 divided by 20 = 3Amps, it could deliver 3 amps of power for 20 hours before it drops below 10.5volts. These tests are typically done at a test lab at a temperature of 25°c.
MCA – Marine Cranking Amps, this is another test from another standard similar to a car battery which states CCA Cold Cranking Amps – how many amps it can deliver in an instant. Some batteries are capable of being a leisure battery and can be used as a starter battery.
DIN – A German industry standard.
SAE – Society of Automotive Engineers, an American standard.
Watt Hours – Watt Hour (Wh) is a unit measurement of power over an hour. A Wh is voltage multiplied by how much current (Amps) the battery can provide in an hour.
12V – All leisure batteries are 12 Volts.
Cycles – This means the number of times the battery can be discharged to 50% and then fully recharged.