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JD5003-00
ADJUSTING FLOAT & EQUALIZE VOLTAGES WITH TEMPCO
Before setting the float and equalize voltages with the remote TempCo probe installed, it is a good idea to
verify that the front panel voltmeter is calibrated, as described in the Operating and Service Instructions,
Section 2.3.7. To do this:
Disconnect one wire from TB8. The error code E 08 will appear on the front panel meter display. To
get rid of the error, de-energize and restart the charger in Float mode.
Connect a digital dc voltmeter to the dc output terminals of the charger.
Press and hold the UP key, then press the EQLZ MTHD key. Release both keys. This places the
charger in the Voltmeter calibration mode. The front panel meter displays the output float voltage.
Press the UP or DOWN key repeatedly until the actual output voltage, measured by your external
digital voltmeter, matches the float voltage shown by the charger's front panel meter. The output
voltage increases or decreases by a small amount each time you press the key. You must press and
release the key once for each increment in output voltage; pressing and holding the key does not cause
the voltage to scroll.
Remember, it is the actual output voltage of the charger that changes when you press the UP or DOWN key,
and the charger's front panel meter stays the same. After you have calibrated the meter, remove your digital
voltmeter, de-energize the charger, reconnect the temperature probe wire to TB8, and restart the charger.
With the TempCo probe connected, working properly, under default factory settings, the front panel meter
always shows the float (or equalize) voltage for a 25°C (77°F) temperature. The actual output voltage of the
charger varies with temperature, such that the actual dc output voltage will almost never match the front
panel meter reading. The temperature probe should be installed in a location that is likely to produce a good
indication of the average temperature of the battery.
When adjusting the float and equalize voltages from the front panel, the displayed voltage is the value at
25°C. The temperature probe determines the actual dc output voltage of the charger. Be sure that the float
and equalize voltages that you set agree with the battery manufacturer's recommendations for 25°C (77°F)
operation.
If you know the probe temperature, you can adjust the float voltage for that exact temperature, using the graph
at the end of this application note. Since the probe has a temperature tolerance of ±0.5°C, you may want to
adjust the float and equalize voltages if they are more than about 1% off. Remember that any adjustment you
make has to be for the average temperature of the entire battery. Changing the float or equalize voltage
doesn't change the slope of the compensation; the change in dc output voltage vs. temperature will still be
correct.
COMPENSATED VS. UNCOMPENSATED
AT Series battery chargers equipped with newer Main Control PC Boards (A1), utilizing firmware Version
6.53 or higher, feature the ability to use either temperature-compensated or un-compensated dc voltages in its
operation and displays. Older boards may only use compensated voltages. Chargers with newer boards are
normally shipped from the factory set for using compensated voltages. Utilize this feature as follows:
Shut down the AT Series battery charger.
Properly install the TempCo probe and cable as defined on Page 5 of this document.
Set jumper (J30) on the Main Control PC Board (A1) to positions 2-3 to use compensated voltages.
or
Set jumper (J30) on the Main Control PC Board (A1) to positions 1-2 to use uncompensated voltages.
Restart the AT Series battery charger per Section 2.1 of the Operating and Service Instructions.
The Main Control PC Board (A1) will detect the installed remote TempCo probe, and the display will
flash Pb (or nicd).
JD5003-00.Rev6.doc
AT10.1/AT30 Series Battery Charger
Page 2 of 8
Rev. 6 - Last Printed 10/31/2014 10:31:00 PM
Application Note
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