Transfer Time; Battery Temperature Sensor Operation; Figure 3-8, Bts Temperature To Charge Voltage Change - Sensata Magnum Energy MS Series Owner's Manual

3.4

Transfer Time

While in Standby mode, the AC input is continually monitored. Whenever AC power falls below
the VAC dropout voltage (80 VAC, default setting), the inverter automatically transfers back to
Inverter mode with minimum interruption to your appliances—as long as the inverter is turned
on. The transfer from Standby mode to Inverter mode occurs in approximately 16 milliseconds.
While the MS Series is not designed as a computer UPS system, this transfer time is usually fast
enough to hold them up. However, the VAC Dropout setting has an eff ect on the ability of the
loads to transfer without resetting. The lower this setting, the longer the eff ective transfer will be
and therefore, the higher the probability for the output loads to reset. This occurs because the
incoming AC voltage is allowed to fall to a level that is so low that when the transfer does occur,
the voltage on the inverter's output has already fallen low enough to reset the loads.
The disadvantage of a higher VAC Dropout setting is that smaller generators (or large generators
with an unstable output) may nuisance transfer. This commonly happens when powering loads that
are larger than the generator can handle—causing the generator's output voltage to constantly
fall below the inverter's input VAC dropout threshold.
Info: When switching from Inverter mode to Standby mode, the inverter waits
approximately 15 seconds to ensure the AC source is stable before transferring.
3.5

Battery Temperature Sensor Operation

The plug-in Battery Temperature Sensor (BTS) is used to determine the battery's temperature.
This information allows the multi-stage battery charger to automatically adjust the battery charge
voltages for optimum charging performance and longer battery life.
If the temperature around an installed BTS is below 77°F (25°C), the absorb and fl oat charge
voltage increases, and if the temperature around the BTS is higher than 77°F (25°C), the absorb
and fl oat charge voltage decreases. See Figure 3-8 to determine how much the charge voltage
changes (increases or decreases) depending on the temperature reading of the BTS. For example,
the nominal absorb charge voltage for a fl ooded battery at 77°F (25°C) on a 24-volt model is
29.2 VDC. If the battery temperature is 95°F (35°C), the absorb charge voltage would decrease
to 28.6 VDC (29.2 VDC–0.6 change).
If a temperature sensor is NOT installed, the charge voltages are not automatically adjusted because
of temperature, but are maintained at a temperature of 77°F (25°C). The life of the batteries may
be reduced if they are subjected to large temperature changes when the BTS is not installed.
Info: When the BTS is connected, the battery charger uses a value of –5mV/°C/Cell
from 0-50°C to change the charge voltage based on temperature.

Figure 3-8, BTS Temperature to Charge Voltage Change

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Operation
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