Functional Design of the mCCHP-RES System - Design for Micro-Combined Cooling, Heating and Power Systems - page 248

where :
A TFA floor area of residence [m 2 ]; total

e max speci c power consumption in the month with the highest consumption of

electricity (kWh/m 2 );

N days number of days in this month.

(b) Choice the voltage for the batteries bank V batteries = V cc and for the battery
V battery .
Technical characteristics of the batteries are voltage and battery capacity. The
battery s capacity, that

energy is either being withdrawn or added to the battery. The voltage of a lead

' s voltage depends on the rate, in relation to the battery '

acid
battery gives a read out of how much energy is available from the battery. Figure 7
illustrates the relationship between the battery

-

s state of charge and its voltage. This
graph is based on a 48-volt battery at room temperature. Rates of charge and
discharge are expressed as ratios of the battery

'

'

s capacity in relation to time. Rate

'

(of charge or discharge) is equal to the battery is capacity in ampere-hours divided

by the time in hours it takes to cycle the battery. If a completely discharged battery
is totally

filled in a 10 h period, this is called a C/10 rate.
Deep cycle lead - acid batteries [ 2 ] which are continually recharged at rates faster
than C/10 will have shortened lifetimes. The literature [ 3 ] indicates that the best
overall charging rate for deep cycle lead - acid batteries is the C/20 rate. The C/20

charge rate assures good ef ciency and longevity by reducing plate stress.

Fig. 7 Rest voltage versus state of charge