Cub Cadet Fun Runner - Manual (Page 7)

2-1
SECTION 2: COMPONENT DESCRIPTION
Battery Pack
The battery pack of the FunRunner consists of
four 12-volt sealed lead acid battery modules.
The modules are situated in the vehicle under
the seat and are covered by the rear body panel.
See Figure 2-1. Since the modules are sealed
and valve regulated, no water or electrolyte can
be added to the batteries.
Figure 2-1:
Each module has a rated capacity of 73 ampere-
hours (Ah) at a 20-hour discharge rate and 48
Ah at the 1-hour discharge rate. The capacity is
the available quantity of electricity in a battery
measured in Ah. Capacity is always related to
some quantity of current in amperes (amps) and
the length of time that the given current can be
produced. The minutes of reserve is a capacity
rating in which the amount of current is set at a
given rate, usually 25 amps, then the length of
time it takes for the battery to reach its
discharged cut-off voltage is measured. This
amount of time in minutes is the reserve
capacity of the battery.
For an electric vehicle like the FunRunner, the
capacity available from the batteries determines
the range of the vehicle. The range is the
distance that can be driven on one battery
charge.
The normal driving range of the FunRunner is
approximately 30 miles when the batteries are
performing at their rated capacity. The battery
capacity and therefore the range can be affected
by several factors however.
Temperature has a dramatic effect on a lead
acid battery’s capacity. The standard
temperature for rating a battery is 78
°
F. At
temperatures above 78
°
F, the capacity will be
higher than the rated capacity. The capacity will
be lower than rated capacity when temperatures
are below 78
°
F. At 32
°
F only about 70 percent
of the rated capacity is available. This is
significant, because if the FunRunner is
operated when the temperature is around 32
°
F,
the range will be reduced by 30 percent.
Another factor effecting capacity is the rate of
discharge. The battery modules in the
FunRunner are rated at 73 Ah for the 20-hour
rate and 48 Ah for the 1-hour rate. That’s a
large difference in the available Ah’s produced
between the two discharge rates. At the 20-hour
rate, the current drawn from the battery is set to
a low value that will take 20 hours to bring the
battery down to its cut-off voltage. The rate of
current in amps times the 20 hours is the
capacity rating. At the 1-hour rate, the current is
set at a much higher rate to bring the battery
down to the cut-off voltage in one hour. With a
73 Ah rating for 20 hours and a 48 Ah rating for
1 hour, it is obvious that the higher the rate of
current draw, the lower the capacity.
The FunRunner will use current at a fairly high
rate, and the higher the rate the shorter the
range will be. If it is driven faster or up hill
frequently, then the current rate will be higher
and the capacity of the battery pack will be
reduced.
The normal chemical process in the battery over
time will reduce the amount of active material on
the plates of the battery. This reduction in active
material will cause a reduction in capacity. In
other words, as the battery ages and more and
more charge/discharge cycles have occurred,
the capacity of the battery will begin to
decrease. When the aging process of the
battery has caused a decrease in capacity so
that the FunRunner no longer has a useable
range, the batteries must be replaced.
The four battery modules of the FunRunner are
wired in series to form a 48-volt battery pack.
When connecting battery modules in series, the
voltage of the pack is the total of the modules in
the series string. See Figure 2-2.