5. Operation
5.1. How does the SmartShunt work?
The main function of the SmartShunt is to follow and indicate the state of charge of a battery, to be able to know how much
charge the battery contains and to prevent an unexpected total discharge.
The SmartShunt continuously measures the current flow in and out of the battery. Integration of this current over time, if it was a
fixed current, boils down to multiplying current and time and gives the net amount of Ah added or removed.
For example: a discharge current of 10A for 2 hours will take 10 x 2 = 20Ah from the battery.
To complicate matters, the effective capacity of a battery depends on the rate of discharge, the Peukert efficiency, and, to a lesser
extent, the temperature. And to make things even more complicated: when charging a battery more energy (Ah) has to be
‘pumped’ into the battery than can be retrieved during the next discharge. In other words: the charge efficiency is less than 100%.
The SmartShunt takes all these factors in consideration when calculating the state of charge.
5.2. Readout overview
The status screen of the SmartShunt displays an overview of important parameters:
• State of charge.
• Battery voltage.
• Battery current.
• Power.
• Aux input reading (starter battery, midpoint or temperature).
State of charge
This is the actual state of charge of the battery in percent and is compensated for both the Peukert efficiency and charge
efficiency. The state of charge is the best way to monitor the battery.
A fully charged battery will be indicated by a value of 100.0%. A fully discharged battery will be indicated by a value of 0.0%.
Please note that if the state of charge indicates three dashes: “---” this means that the SmartShunt is in an unsynchronised state.
This mainly occurs when the SmartShunt has just been installed or after the SmartShunt has been left unpowered and is powered
up again. For more information, see paragraph 5.3: “Synchronising the SmartShunt”.
Voltage
This is the terminal voltage of the battery.
Current
This is the actual current flowing in or out of the battery. A negative current indicates that current is taken from the battery. This is
the current needed for DC loads. A positive current means that current is going into the battery. This is current coming from
charge sources. Keep in mind that the SmartShunt will always indicate the total battery current, being the current traveling into the
battery minus the current traveling out of the battery.
Power
The power drawn from or received by the battery.
Consumed Ah
The SmartShunt keeps track of the Amp-hours removed from the battery compensated for the efficiency.
Example: If a current of 12A is drawn from a fully charged battery for a period of 3 hours, the readout will show -36.0Ah (-12 x 3 =
-36).
Please note that if the Consumed Ah indicates three dashes: “---” this means that the SmartShunt is in an unsynchronised state.
This mainly occurs when the SmartShunt has just been installed or after the SmartShunt been left unpowered and is powered up
again. For more information, see paragraph 5.3: “Synchronising the SmartShunt”.
Time remaining
The SmartShunt estimates how long the battery can support the present load. This is the “time-to-go” readout and is the actual
time left until the battery is discharged to the set “discharge floor”. The discharge floor is by default set at 50%. For the discharge
floor setting see paragraph 7.1.3: “Discharge floor”. If the load is fluctuating heavily, it is best not to rely on this reading too much,
as it is a momentary readout and should be used as a guideline only. We recommend the use of the state of charge readout for
accurate battery monitoring.
Manual - SmartShunt
Page 12
Operation
