Lester 25680 User manual

www.lesterelectrical.com 134748 A
72 VOLT BATTERY DISCHARGE UNIT
MODEL 25680
PLEASE SAVE THESE IMPORTANT SAFETY AND OPERATING INSTRUCTIONS
For correct operation of the equipment, it is important to read and be familiar
with this entire manual before installing and operating the discharger.
DO NOT DISCARD THIS MANUAL AFTER READING.
LOOK FOR THIS SYMBOL TO POINT OUT SAFETY PRECAUTIONS. IT MEANS:
BECOME ALERT—YOUR SAFETY IS INVOLVED. IF YOU DO NOT FOLLOW THESE
SAFETY INSTRUCTIONS, INJURY OR PROPERTY DAMAGE CAN OCCUR.
A discharge unit is used to measure the remaining
or proportional useful energy for which a battery set
is capable. Since slightly different methods are used
when determining a battery's useful energy, this
discharge unit has the capability of being
programmed to use a variety of discharge times and
shut-off voltages. Other features which have been
designed in are:
•Operates from battery voltage only (no AC supply)
•Used on 72 volt battery systems only
•Electronically controlled (uses microcontroller)
•Programmable voltage or time shut-off
•LED digital display for easy reading
•Built-in thermal protection
•8 foot DC cord with cord wrap built into handle
•Durable eighteen gauge (18 Ga.) steel case with
powder coat paint
•Large 500 amp alligator clamps for battery
connections
•Three minute test cycle feature for measuring cell
voltages
•Discharge data can be viewed or saved with a
terminal or computer
IMPORTANT SAFETY INSTRUCTIONS
1. This manual contains important safety and
operating instructions for discharge unit Model
25680.
2. Before using discharge unit, read all instructions
and cautionary markings on electric vehicle,
battery, battery charger, and all accessories
using battery.
3. Position the discharger on a foundation of stone,
brick, concrete or grounded metal.
4. TO REDUCE THE RISK OF FIRE, DO NOT
USE THE DISCHARGER NEAR FLAMMABLE
MATERIALS OR VAPORS.
5. Do not expose discharge unit to rain or snow.
6. Use of an attachment not recommended or sold
by the discharge unit manufacturer may result in
a risk of fire, an electric shock, or injury to
persons.
7. Make sure DC cord is located so that it will not
be stepped on, tripped over, or otherwise
subjected to damage or stress.
8. Do not operate discharge unit with damaged
cord or clamp; replace it immediately.
9. To permit free air flow for cooling, allow eighteen
inches (18") minimum between the discharger
and any wall or other equipment.
*34748*

www.lesterelectrical.com 234748 A
10. Do not touch the back or sides of the case
during or just after operation of the discharge
unit. A large amount of energy is being
dissipated by the unit and the case will become
hot.
11. NEVER disconnect the discharge unit from the
batteries while the unit is operating. This will
subject the unit to heat stress and may
immediately damage or shorten the life of the
unit.
12. Do not operate discharge unit if it has received a
sharp blow, been dropped, or otherwise
damaged in any way; take it to a qualified
service center.
13. Do not disassemble discharge unit; take it to a
qualified service center when service or repair is
required. Incorrect reassembly may result in a
risk of electric shock or fire.
14. To reduce risk of electric shock, disconnect
discharge unit from batteries before attempting
any maintenance or cleaning.
RECEIVING AND INSTALLING THE UNIT
When the discharge unit is received, check for
possible in-transit damage. If any damage is found,
it should be reported as a claim to the carrier.
Proper operation of the discharge unit is important in
order to achieve good performance and to prevent
damage to the discharger and batteries. The
discharge unit should be located in a clean, cool,
dry, and well ventilated area. To permit free air flow
for cooling, allow eighteen inches (18") minimum
between the discharger and any wall or other
equipment. Position the discharger on a foundation
of stone, brick, concrete or grounded metal.
DANGER: TO REDUCE THE RISK OF FIRE,
DO NOT USE THE DISCHARGER NEAR
FLAMMABLE MATERIALS OR VAPORS.
THEORY OF OPERATION
The importance of using a discharge unit on battery
sets is two-fold:
1. To determine battery capacity.
2. To find defective cells or batteries in a battery
set.
These are accomplished by conducting a discharge
under controlled conditions as specified by the
American Golf Car Manufacturers Association
(AGCMA). The AGCMA has outlined battery
capacity measurements as follows:
Battery energy is measured in minutes obtained
upon discharging a fully charged 72 volt battery
set with a 75 amp resistive load at a temperature
of 80°F until a shut-off voltage of 63 volts (1.75
volts per cell) is reached.
To test a set of batteries to the above specification,
the battery is to be first completely charged. This
means charging the battery until the specific gravity
of the battery cells does not change in three
consecutive readings taken one hour apart.
A discharge unit is then connected to the battery and
a discharge started. Applying the 75 amp average
load will lower the voltage immediately to slightly
below nominal voltage. As the discharge
progresses, the voltage will decrease gradually at
first, then fall faster until the pre-selected shut-off
voltage is reached and the discharge shuts off.
Testing battery capacity
Battery capacity is expressed as the percentage of
time at which shut-off voltage was reached.
Example:
A 36 cell battery set rated at 107 minutes at 75
amp discharge rate is to be tested to a shut-off
voltage of 63 volts. Upon discharging a set of
fully charged batteries, the discharge unit shut
off in one hour and 32 minutes (92 minutes).
Battery capacity is therefore expressed as:
(92 / 107) * 100% = 86.0%.
Use both the battery manufacturer specifications for
battery capacity and battery performance when
determining the appropriate time for battery
replacement.
Testing for defective cells
During a discharge, all cells in a set should decrease
in voltage nearly evenly. Right before the discharger
shuts off at 31.5 volts (assuming all cells being
good), the total battery voltage is composed of 36
cells supplying 1.75 volts each or 6 twelve volt
batteries supplying 10.5 volts each. Should one or
more cells decrease faster or fail to hold their
respective load, the total discharge time will be less
to the extent it probably will not be acceptable. If, for
example, one battery is yielding only 8 volts, the
balance of the batteries must make up for this
deficiency. Further, the 8 volts for this one battery
could be caused by one or more cells being deficient
in this battery.
After the discharge unit shuts off at 63 volts, restart
the discharger to quickly monitor the individual cell
or battery voltages while the batteries are underload.
If cell or battery voltages vary considerably or any
cell voltage is below 1.75 volts or battery voltage is
below 10.5 volts, replace the low cells or batteries.
Caution should be observed, as the cells or batteries
with higher voltages should not be taken below 1.75
volts per cell (10.5 volts per battery). Some
experience will be needed to judge these conditions.

www.lesterelectrical.com 334748 A
OPERATING INSTRUCTIONS
The discharge unit is designed for long, trouble-free
service. It features a five-digit display and two push
buttons which are used to interact with the user. A
nine-pin, D-subminiature connector can also be
connected to a terminal or computer to display
discharge data.
The discharge unit is a DC-only unit. Connect the
two alligator clamps to the batteries to power up the
discharge unit. Make sure the clamps are properly
connected to the battery posts. The RED clamp
connects to the positive post (+), and the BLACK
clamp connects to the negative post (-).
WARNING: NEVER DISCONNECT THE
DISCHARGE UNIT FROM THE BATTERIES
WHILE THE UNIT IS OPERATING. THE LARGE
AMOUNT OF ENERGY BEING DISSIPATED BY
THE RESISTIVE ELEMENT COULD CAUSE
DAMAGE TO THE DISCHARGE UNIT IF THE FAN
IS NOT RUNNING.
Pressing the START/STOP button will begin a
discharge cycle. The discharge unit has been
designed to have several methods for terminating a
discharge cycle:
•Pressing the START/STOP button (can be used
like a pause button)
•Maximum time shut-off (programmable from 5 -
240 minutes)
•Shut-off voltage
•Over temperature shut-off
When a discharge cycle has been terminated, check
to see which type of shut-off has occurred. If the
value in Func2 is the value programmed for the
maximum timer, then the terminating method was by
maximum time shut-off. If the value in Func3 is the
value programmed for the shut-off voltage, then the
terminating method was by shut-off voltage. If
neither of the above methods were true, then the
discharge unit shut-off by over temperature or by
someone pressing the START/STOP button. When
this occurs, make sure nothing is blocking the
ventilation area around the discharge unit (keep unit
at least eighteen inches (18") from walls or other
equipment). Also check and make sure the fan is
operating properly by restarting, then stopping the
unit.
Operating the push buttons
The two buttons control all of the operations of the
discharge unit. The left button is labeled START/
STOP and the right button is labeled DISPLAY.
Both buttons are used in a variety of ways to make
the operation simple.
START/STOP button
When the discharger unit is connected to a set of
batteries, it powers up in the off condition, with
"OFF" being displayed for about five (5) seconds.
Pressing the START/STOP button will start the
discharge unit as indicated by the message "ON". If
the button is pressed again, the unit will shut off, as
indicated by the message "OFF". If this button is
pressed again, the unit will restart and continue from
where it was stopped. As long as the battery
remains connected to the discharge unit, this button
can be used to start and stop a discharge without
losing the total discharge time.
After the unit has stopped, either by maximum timer
or by reaching the shut-off voltage, a test discharge
cycle may be started by pressing the START/STOP
button. A test cycle will run for three minutes, which
should allow you enough time to measure the
individual cell voltages to check for bad cells. If
more time is needed, press the START/STOP button
again to start another test cycle.
DISPLAY button
The DISPLAY button is used to display several
different values. Press the button to show the
function, then release it to show its present value.
The following functions can be displayed:
Func1 -Present battery voltage
Func2 -Discharge time in minutes and seconds
(minutes are displayed on the left and
seconds to the right of the decimal point)
Func3 -Lowest battery voltage reached during
discharge
Func4 -Battery voltage sensed (72)
Func5 -Discharge data printout interval (# of
seconds)
PROGRAMMING INSTRUCTIONS
The discharge unit also has several values which
are programmable. This allows more flexibility to
vary the discharge depending on the batteries and
the desired discharge method. The following values
can be programmed:
•Maximum discharge time
•Shut-off voltage
•Terminal format
The values for these variables can be changed at
any time, even while a discharge cycle is running.
Changing the maximum timer
The default discharge time is 240 minutes. This
value is the maximum time the discharge unit allows
to discharge a set of batteries.

www.lesterelectrical.com 434748 A
To increase the maximum timer if it has been
decreased from the default value, press and release
the DISPLAY button until Func1is displayed.
Continue to hold in the DISPLAY button while you
press and release the START/STOP button. Every
time you press and release the START/STOP
button, the maximum timer will increase by five
minutes. When you are finished increasing the
maximum timer to the desired value, release the
DISPLAY button.
To decrease the maximum timer from 240 minutes,
press and release the DISPLAY button until Func2is
displayed. Continue to hold in the DISPLAY button
while you press and release the START/STOP
button. Every time you press and release the
START/STOP button, the maximum timer will
decrease by five minutes. When you are finished
decreasing the maximum timer to the desired value,
release the DISPLAY button.
Changing the shut-off voltage
When the unit is powered up, the shut-off voltage
defaults to its lowest programmable value of 63 volts
(1.75 volts per cell).
To increase the shut-off voltage from the default
setting, press and release the DISPLAY button until
Func3 is displayed. Continue to hold in the
DISPLAY button while you press and release the
START/STOP button. Every time you press and
release the START/STOP button, the shut-off
voltage will increase by 0.1 volts. When you are
finished increasing the shut-off voltage to the
desired value, release the DISPLAY button.
To decrease the shut-off voltage if it has been
increased from the default setting, press and release
the DISPLAY button until Func4 is displayed.
Continue to hold in the DISPLAY button while you
press and release the START/STOP button. Every
time you press and release the START/STOP
button, the shut-off voltage will decrease by 0.1
volts. When you are finished decreasing the shut-off
voltage to the desired value, release the DISPLAY
button.
Changing the discharge data printout interval
Connect a terminal or computer to the nine pin D-
subminiature connector on the discharge unit. The
terminal format is set up to transmit at 1200 baud
with 8 bits, 1 stop bit, and no parity. The default
print routine for the discharge unit is to print data in
one minute intervals but only when the unit is on.
This can be changed to print data once a second by
pressing and releasing the DISPLAY button until
Func5 is displayed. Continue to hold in the
DISPLAY button while you press and release the
START/STOP button. This changes the value
displayed from 60 to a one. If you wish to change
the print routine back to the default setting, press
and release the DISPLAY button until Func5 is
displayed. Continue to hold in the DISPLAY button
while you press and release the START/STOP
button. This changes the value displayed from one
back to a 60.
The display format for the discharge data is the
following: aaaaa bbbbb ccccc ddddd
where aaaaa =discharge time in minutes
bbbbb =discharge time in seconds
ccccc =present battery voltage
ddddd =lowest battery voltage during
discharge