Samlexpower PST-1500-12 Owner's Manual - Section 7 |
18 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 19
Reserve capacity is the time in minutes for which the battery can deliver 25 Amperes at
80ºF(26.7ºC)tillthevoltagedropsto1.75V/Celli.e.10.5Vfor12Vbattery,21Vfor24V
battery and 42V for 48V battery.
Approximaterelationshipbetweenthetwounitsis:
Capacity “C” in Ah = Reserve Capacity in RC minutes x 0.6
7.5 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
*BatteryCouncilInternational;**GolfCart
7.6 SPECIFYING CHARGING / DISCHARGING CURRENTS: C-RATE
Electricalenergyisstoredinacell/batteryintheformofDCpower.Thevalueofthe
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.
Asexplainedabove,theamountofstoredelectricalenergyisalsocalledtheCapacityof
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
purposesofspecifyingAhcapacitydependsuponthetypeofapplication.Letusdenote
thisdischargetimeinhoursby“T”.Letusdenotethedischargecurrentofthebattery
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”
Table7.2belowgivessomeexamplesofC-Ratespecificationsandapplications:
TABLE 7.2: DISCHARGE CURRENT RATES - “C-RATES”
Hours of discharge time “T” till
the “End Point Voltage”
"C-Rate" Discharge Current in Amps =
Capacity "C" in Ah
÷
Discharge Time
"T" in Hrs.
Example of C-Rate
Discharge Currents
for 100 Ah battery
0.5 Hrs.
2C
200A
1 Hrs.
1C
100A
5 Hrs. (Inverter application)
C/5 or 0.2C
20A
TableContinuesNextPage}
Section 7 |
General information on Lead Acid