9.1.2. Connecting and monitoring midpoint in a 48V battery bank
Due to the voltage drop over the positive and the negative cables the midpoint voltage are not identical.
In an unmonitored battery bank the midpoints should not be interconnected, one bad battery bank can go unnoticed and could
damage all other batteries.
Always use busbars when applying midpoint voltage monitoring. The cables to the busbars must all have the same length.
Midpoints can only be connected if corrective action is taken in case of an alarm.
9.2. Midpoint deviation calculation
The SmartShunt measures the midpoint and then calculates the deviation in a percentage from what the midpoint should be.
Where:
d is the deviation in %
Vt is the top string voltage
Vb is the bottom string voltage
V is the voltage of the battery (V = Vt + Vb)
9.3. Setting the alarm level
In case of VRLA (gel or AGM) batteries, gassing due to overcharging will dry out the electrolyte, increasing internal resistance
and ultimately resulting in irreversible damage. Flat plate VRLA batteries start to lose water when the charge voltage approaches
Manual - SmartShunt
Page 29
Midpoint voltage monitoring
