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F. Equalization Interval–Equalizations are typically done once a month. Most of the
cycles are 28 days so the equalization will begin on the same day of the month. It can
be set by Dip Switch 3~5 for different interval days. Each new cycle will be reset as
the equalization starts so that a setting day period will be maintained.
Temperature Effects
Battery Temperature Sensor (BTS)
A sensor next to the remote panel is used for temperature compensated battery charging.
As the battery gets warmer, the gassing increases. As the battery gets colder, it becomes
more resistant to charging. Depending on how much the battery temperature varies, it
may be important to adjust the charging for temperature changes.
There are three battery charging parameters that are affected by temperature:
PWM Absorption
This is the most important part of charging that is affected by temperature because the
charging may go into PWM absorption almost every day. If the battery temperature is
colder, the charging will begin to regulate too soon and the battery may not be recharged
with a limited solar resource. If the battery temperature rises, the battery may heat and
gas too much.
Equalization
A colder battery will lose part of the benefit of the equalization. A warmer battery may
heat and gas too much.
Float
Float is less affected by temperature changes, but it may also undercharge or gas too
much depending on how much the temperature changes.
The BTS corrects the three charging setpoints noted above by the following values:
• 12 volt battery: –0.030 volts per °C (–0.017 volts per °F)
• 24 volt battery: –0.060 volts per °C (–0.033 volts per °F)
• 48 volt battery: –0.120 volts per °C (–0.067 volts per °F)
Variations in battery temperature can affect charging, battery capacity, and battery life.
The greater the range of battery temperatures, the greater the impact on the battery. For
example, if the temperature falls to 10°C (50°F) this 15°C (27°F) change in temperature
will change the PWM, equalization and float setpoints by 1.80V in a 48V system.
Temperature
50ºC / 122ºF
45ºC / 113ºF
40ºC / 104ºF
35ºC / 95ºF
30ºC / 86ºF
25ºC / 77ºF
20ºC / 68ºF
15ºC / 59ºF
12 Volt
24 Volt
– 0.75 V
–1.50 V
– 0.60 V
– 1.20 V
– 0.45 V
– 0.90 V
– 0.30 V
– 0.60 V
– 0.15 V
– 0.30 V
0 V
0 V
+ 0.15 V
+ 0.30 V
+ 0.30 V
+ 0.60 V
13
48 Volt
– 3.00 V
– 2.40 V
– 1.80 V
– 1.20 V
– 0.60 V
0 V
+ 0.60 V
+ 1.20 V
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