8
1.2.6 External Temperature Compensation (Option 11W/11Y)
The natural voltage of a battery changes as a function of temperature change. As the battery temperature
rises, the effective voltage of the battery decreases. Without Temperature Compensation, the battery charger
will always produce a set constant output voltage. As the battery temperature increases, this constant voltage
will then induce a higher output current from the charger. This higher current can result in overcharging the
battery, which in turn can result in damage to the batteries.
Temperature Compensation combats this overcharging by adjusting the charger’s output voltage based on the
temperature read by the temperature probe. In order to increase the accuracy of the temperature
compensation the external probe can be used to measure the temperature of the battery.
Option 11W includes the compensation circuit and a 24 foot long temperature probe. Option 11Y includes the
compensation circuit and a 100 foot long temperature probe. With either option approximately two feet of the
probe is taken inside the charger enclosure.
External Probe Connection Procedure
Before making any connections to the ESCR ensure that the AC Power is off at the main breaker box.
Disconnect the battery from the charger via the battery disconnect breaker or manually disconnecting the
battery cables. Verify that no voltage is present by using a voltmeter at all input and output terminals.
To connect the external probe the JP4 jumper must be removed. Removing this jumper will disable the
charger's internal temperature compensation.
On the charger side, simply plug the probe's 3 pin connector in the C11 connection on the Control/Alarm Board.
Install the remaining lug of the probe to the battery. As battery setups vary between customers and battery
manufacturers, it is recommended that the battery manufacturer be consulted for placement of the probe. The
lug of the probe is completely isolated from the compensation circuitry, so the battery voltage will not affect the
compensation.
With the probe connected, enter the configuration and make sure that Temperature Compensation has been
enabled (For more details see section 2.3).
Figure 8 - Temperature Probe Connection
