We measured the recharge characteristics of the battery
in relation to changes in the daylight characteristics
of solar cells. The battery was emptied by discharge to a
load before recharging and measuring. Figures 4 and 5
show measuring results at room temperature (26 °C) while
results at low temperature (O °C), with the battery put in a
refrigerator, are charted in Figures 6 and 7. These simulation
test results suggest that recharging a battery in summer
is done more effectively than in winter. Although the
battery voltage may apparently rise quickly in winter, the
recharged current fluctuates violently. This witnesses that
recharging in winter is liable to be insufficient.