Siemens SITOP DC UPS 6EP1931-2FC21, Considerations For Use

6.2 Discharge Characteristics for Lead-Gel Battery Modules 

Diagram 6: Discharge characteristics for lead-gel battery modules 

Definitions: 

DISCHARGING CURRENT = Output or charging current of SITOP DC UPS module 

Ordinate = Battery voltage in V, abscissa = discharging time in seconds/minutes/hours 



5C

 means: 

Charging current = 

5 x 

battery capacity x 1/h  

(i.e., in case of a 3.2Ah battery module, 5C is a charging current of 5 x 3.2Ah x 1/h = 16A) 



3C

 means: 

Charging current = 

3 x 

battery capacity x 1/h   

(i.e., in case of a 3.2Ah battery module, 3C is a charging current of 3 x 3.2Ah x 1/h = 9.6A,  

while, in case of a 7Ah battery module, 3C is a charging current of 3 x 7Ah x 1/h = 21A) 



1C

 is particularly easy:  

3.2A charging current for a 3.2Ah battery module, 7A charging current 

for a 7Ah battery module, or 12A charging current for a 12Ah battery module). 



0.2C

 means:

 charging current = 

0.2 x battery capacity x 1/h   

(i.e., in case of a 12Ah battery module, 0.2C is a charging current of 0.2 x 12Ah x 1/h = 2.4A) 

and so on 

 
© Siemens AG, 2009 

16/18