Page 47 - Battery Reference Book

1/32 Introduction to battery technology
i.e. and the weight of water consumed during discharge is
100
- total solution ww = (W3 - W4)
ml
s1
Therefore
g H2S04 per 100ml (C1% w/w) acid = ClSl (1.82)

g H20 per 100ml (C1% w/w) acid =
1.8305 As it is known from theory that for every 196 g (2 mol)
of sulphuric acid consumed 36g (2mol) of water are
At the end of discharge, we have C2% H2S04, i.e. produced, if the weight of sulphuric acid consumed is
C2 g 100% H2S04 per 1OOg C2% H2S04 WA g then (WA x 36)/196g of water are produced, i.e.
WA x 36
i.e. w, = ~ 196
100
0
~
ml100% ~ 2 ~ per 4- ml~2% 2 ~ 0 4 Thus, if
1.8305 s2
comprising
then
36 x WA VF x S2 100 C2
and 196 - 100 ((1 -E)
100 c2 ml water
S2 1.8305
i.e. loo/& ml total solution. These two equations can be solved for VI and VF:
g H2S04 per 100ml (C2% w/w) acid = C2S2 100 I
c VF = (1.83)
g H20 per lOOml (C2% w/w) acid = - 2)
-
s2
( yzo 1.8305
If VI and VF, respectively, denote the volumes of acid
in the cell at the start and the end of the discharge
process, the weight (in g) of 100% H2SO4 in the cell
at the start of discharge is
VI x c1 x SI
w1= (1.77)
100
the weight of 100% H2S04 in the cell at the end of (1.84)
discharge is
and the net volume decrease in electrolyte occurring
on discharge is
(1.78)
the weight of 100% H2S04 consumed during dis-
charge is
= 0.3627 x WA (1.85)
WA = w1 - w2
VI x c1 X s1 VF X c2 X s2
7
-
- - (1.79) 1 .I Calculation of operating
100 100 parameters for a lead-acid battery
the weight of water in the cell at start of discharge is
from calorimetric measurements
(1.80) Suppose that when the electrochemical cell reaction
n n
the weight of water in the cell at the end of discharge is -Pb + -Pb02 + nH2S04 = nPbS04 + nH2O
2
2
is carried out in a calorimeter the observed number
(1.81) of calories produced during a discharge is denoted by