Outback Power Systems GS8048 Operator Manual - Manual (Page 27)

Operation
900-0020-01-00 Rev B 25
Battery Temperature Compensation
Temperature compensation is a process that corrects for changes in battery performance caused by
varying temperature.
When batteries are cooler than room temperature (77°F or 25°C), the electrolyte reaction slows down.
This causes the battery to accept charging energy less readily. Delivering the usual amount of energy
that would fully recharge a battery at room temperature will undercharge a cool one.
Conversely, when batteries are warmer than room temperature, the electrolyte reaction is somewhat
hyper-reactive. It takes less energy than usual to charge them. Delivering the full (room-temperature)
amount of energy would overcharge them and can be hard on them over time.
The Radian inverter, when equipped with the Remote Temperature Sensor (RTS) will compensate for
changes in temperature. The RTS is attached to a single battery near the center of the bank, to achieve
a representative temperature. If installed in a multiple-inverter system, only a single RTS is necessary.
It must be plugged into the master inverter and will control the charging of all slaves and all charge
controllers. (See the Radian Series Inverter/Charger Installation Manual for locating the RTS port.) This
process is automatic.
When charging, an inverter system with an RTS will increase or decrease the charge voltage by 5 mV
per degree Celsius per battery cell. This setting affects the Absorption, Float, and Equalization set
points. The Sell Voltage and Re-Float Voltage set points are not temperature compensated. The
Equalization set points are not compensated in OutBack charge controllers.
 In a 48 Vdc system (24 cells, 2 volts each), this means 0.12 volts per degree Celsius above or below 25°C.
Maximum compensation is ± 2.4 Vdc.
EXAMPLES:

A 48 Vdc system with batteries at 15°C will compensate its charging to 1.2 Vdc higher than the set points.
 A 48 Vdc system with batteries at 40°C will compensate its charging to 1.8 Vdc lower than the set points.
Some batteries require different amounts of compensation. The OutBack FLEXmax Extreme charge
controller has an adjustable rate of compensation (“slope”) and is not limited to 5 mV. The FLEXmax
Extreme can be networked with the Radian with the HUB Communications Manager. If this is done,
the Radian can import the slope setting from the charge controller. See the FLEXmax Extreme manual
for more information.
Temperature compensation only applies to the battery charging function. Other set points in the
inverter, such as the AUX functions, are not compensated for temperature.