Battery Temperature Sensor Operation; Figure 3-4, Bts Temperature To Charge Voltage Change - Magnum Energy MS-PAE Series Owner's Manual

3.2.2 Transfer Time
While in the Standby Mode, the AC input is continually monitored. Whenever AC power falls below
the VAC dropout voltage (80 VAC per leg, default setting), the inverter automatically transfers back
to the Invert 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-PAE 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 effect on the ability of the
loads to transfer without resetting. The lower this setting, the longer the effective 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
(in addition to the relay transfer time) the voltage on the inverters output has already fallen low
enough level 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 to constantly fall
below the inverters input VAC dropout threshold.
Info: When switching from Inverter Mode to the Standby Mode, the inverter waits ap-
proximately 15 seconds to ensure the AC source is stable before transferring.

3.3 Battery Temperature Sensor Operation

The plug-in Battery Temperature Sensor (BTS) is used to determine the battery temperature around
the batteries, this information allows the multistage battery charger to automatically adjust the
battery charge voltages for optimum charging performance and longer battery life.
When the BTS is installed, the charge voltage while in the Bulk, Absorb or Float charge mode will
either increase or decrease if the battery temperature is greater or lower than 77°F (25°C). If the
temperature around the BTS is below 77°F (25°C) the charge voltage increases and if the tem-
perature around the BTS is higher than 77°F (25°C), the charge voltage decreases. The further
the temperature change from 77°F (25°C), the greater the change in the charging voltage. See
fi gure 3-4 to determine how much the charge voltage changes (increases or decreases) depend-
ing 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 29.2VDC. If the battery temperature is 95°F
(35°C), the Absorb charge voltage would decrease to 28.6VDC (29.2 nominal - 0.6 change).
If the temperature sensor is NOT installed, the charge voltages will not be compensated and
charges at a temperature of 77°F (25°C). Without the BTS installed, the life of the batteries may
be reduced if they are subjected to large temperature changes.
Info: The temperature to voltage compensation slope the BTS uses is 5mV/°C/Cell
from 0-50°C.

Figure 3-4, BTS Temperature to Charge Voltage Change

© 2009 Magnum Energy Inc.
T em p eratu re C o m p en satio n u sin g B T S
2 4 V D C u n its
+1.5 V
0.75
+1.2 V
0.6
+0.9 V
0.45
+0.6 V
0.3
+0.3 V
0.15
N o C hange
0
-0 .3V
-0.15
-0 .6V
-0.3
-0 .9V
-0.45
-1 .2V
-0.6
-1 .5V
-0.75
0C 5C 10C 15C
0 5 1 0 1 5
32F 41F 50F 59F
Tem perature reading from BTS (in degrees )
no B T S
c onnec ted
20C 25C 30C 35C 40C 45C
2 0 2 5 3 0 3 5 4 0 4 5
68F 77F 86F 95F 104F 113F
Operation
4 8 V D C u n its
+3 .0V
+2 .4V
+1 .8V
+1 .2V
+0 .6V
N o C hange
-0.6V
-1.2V
-1.8V
-2.4V
-3.0V
50C
5 0
122F
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