Samlex America PST-300-24 - Manual (Page 17)

16 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 17
seCtIOn 7 | General Information on Batteries for
Powering Inverters
typical Battery Sizes
The Table 7.1 below shows details of some popular battery sizes:
tABLe 7.1: PoPULAR BAtteRY SiZeS
Bci* Group Battery Voltage, V Battery capacity, Ah
27 / 31 12 105
4D 12 160
8D 12 225
GC2** 6 220
* Battery Council International; ** Golf Cart
Specifying charging / Discharging currents: c-Rate
Electrical energy is stored in a cell / battery in the form of DC power. The value of the
stored energy is related to the amount of the active materials pasted on the battery
plates, the surface area of the plates and the amount of electrolyte covering the plates.
As explained above, the amount of stored electrical energy is also called the Capacity of
the battery and is designated by the symbol “C”.
The time in Hours over which the battery is discharged to the “End Point Voltage” for
purposes of specifying Ah capacity depends upon the type of application. Let us denote
this discharge time in hours by “T”. Let us denote the discharge current of the battery
as the “C-Rate”. If the battery delivers a very high discharge current, the battery will be
discharged to the “End Point Voltage” in a shorter period of time. on the other hand,
if the battery delivers a lower discharge current, the battery will be discharged to the
“End Point Voltage” after a longer period of time. Mathematically:
eQUAtion 1:
Discharge current “c-Rate” = capacity “c” in Ah ÷ Discharge time “t”