4.2 Detailed Description
4.2.1 SOC (State Of Charge) Calculation
With the help of a proprietary patented software algorithm, the System-Manager is capable to ”learn“ the
characteristics and parameters of the battery. This SOC reading is very accurate and therefore is the
basis for most controlling and monitoring functions. However, if system components are directly
connected to the battery, the state of charge can only be determined with the help of the optional current
sensors HS200. The state of charge always refers to the actual capacity which the battery has in
accordance to its age. So a SOC of 50 % does not mean that half of the battery’s nominal rated capacity
can be used, but that only half of the battery’s REAL MEASURED capacity is remaining.
The state of charge is not dependant on the battery voltage, but on the amount of energy taken out.
Traditional controllers usually determine a final load voltage that hardly ever corresponds to the discharge
depth. During discharge, nominal acid density is being reduced and sulphates are placed on the battery
plates. If discharge is too deep, this growth leads to harmful sulphatation that reduces the battery’s
capacity considerably, thus making the battery useless for energy storage. The traditional measuring
procedures (Ah balancing, acid density measuring) are time-consuming and cost intensive and are
seldom integrated in charge controllers.
If generators or loads are directly connected to the battery without current sensor HS200, the SOC gets
“tricked” and its determination is wrong. However, despite erroneously measured SOC values., the
System-Manager still prevents the battery from falling below certain voltage values, in order to protect the
battery from a too-deep damaging discharge
The System-Manager is able to convert to a voltage regulation mode (chapter 6.5, page 13). Now
System-Manager will operate like a conventional charge controller. We recommend this conversion when
using additional generators (diesel, wind, etc.) or loads which are connected direct to the battery (inverter,
etc.). See for option 2.2 current sensor HS200, too.
4.2.2 Overcharge Protection
The overcharge protection prevents uncontrolled gassing within the battery cells. The gas development is
depending on the acid temperature and cell voltage. So the System-Manager monitors the ambient
temperatures and adjusts the battery’s maximum allowed charge
voltage. The overcharge protection and voltage limitation is
independent on the battery’s state of charge, since the
decomposition of electrolyte is exclusively depending on the voltage
and the temperature. This means that charging is already limited
even though the battery is not completely charged.
Overcharging the battery leads to uncontrolled gassing. Here the
electrolyte is decomposed into oxygen and hydrogen. The
consequences are harmful oxidation processes and mechanical
damages since the gas blisters may knock out active lead material
from the lead plates.
What is even worse is that the uncontrolled gassing in closed
batteries e. g. sealed or fluid batteries where the gas pressure can
even burst or crack the battery case. Frequent overcharging damages the battery casing. The charging
process and the overcharge protection are thus regulated by a new hybrid System-Manager utilizing
pulse width modulation in order to insure smooth battery charging. The user in particular should not
choose a float voltage too high via user settings. If you want to program this value individually from the
System-Manager’s factory setting, please take note of the battery manufacturers' recommendations.
-20
-40
-10
-14
-0
32
10
50
20
68
30
86
40
104
50
122
2,20
2,25
2,30
2,35
2,40
2,45
2,50
2,55
2,60
13,2
13,5
13,8
14,1
14,4
14,7
15,0
15,3
15,6
equ
alis
atio
n S
OC
< 4
0%
boo
st S
OC
<7
0%
norm
al
°C
°F
4.2.3 Temperature Compensation Of Final Charge Voltage
As the battery temperature increases, the acid/lead battery’s optimal final load voltage decreases. A
constant final charge voltage leads to uncontrolled gassing in the case of higher battery temperatures,
and undercharging in case of low temperatures. The temperature compensation software algorithm
automatically decreases the final charge voltage at higher temperatures and increases them at lower
ones. The temperature compensation system with the sensor integrated in the System-Manager
influences all three overcharge thresholds.
•
The attached external battery temperature sensor should therefore be mounted next to the battery to
determine the exact temperature.
8
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