Algorithm; Soc Calculation; Charge And Discharge/Load Relay - 123electric Smart BMS gen 3 Manual

Algorithm

SOC calculation

The SOC is calculated by constantly measuring
the in- and outgoing currents and integrating
these currents. This is called Coulomb
counting. The SOC is recalibrated every time
the pack is full and empty. This is done to
reduce SOC calculation deviations.
In BMS "normal mode", the SOC is set to 100%
when all cell voltages are >= V-balance.
In BMS "critical mode", the SOC is set to 100%
when the total pack voltage is >= V-balance x
Normal mode
Enable
All cell voltages < V-
balance
AND SOC < charge
restart
AND cell temperature
> T-min
AND cell temperature
< T-max
AND cell
communication
Critical mode
Enable
All cell voltages < V-
max
AND cell temperature
> T-min
AND cell temperature
< T-max
AND cell
communication
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The Netherlands
E-mail: info@123electric.eu
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Charge
Disable
Cell voltage >= V-max
All cell voltages >= V-
balance
Cell temperature < T-
min
Cell temperature > T-
max
No cell
communication
Charge
Disable
Cell voltage >= V-max
Cell temperature < T-
min
Cell temperature > T-
max
No cell
communication
total number of cells. In other words, when
the average cell voltage is >= V-balance.
When one of the cell voltages is below V-min
for a longer time while discharging is not
allowed, the SOC is set to 0%.

Charge and discharge/load relay

The tables below display the conditions for
each relay to switch on or off, depending on
the selected mode.
Discharge/load
Enable
All cell voltages > V-
min
AND SOC >= discharge
restart
AND cell temperature
> T-min
AND cell temperature
< T-max
AND cell
communication
Discharge/load
Enable
All cell voltages > V-
min
AND cell temperature
> T-min
AND cell temperature
< T-max
AND cell
communication
19
Disable
Cell voltage <= V-min
Cell temperature < T-
min
Cell temperature > T-
max
No cell
communication
Disable
Cell voltage <= V-min
Cell temperature < T-
min
Cell temperature > T-
max
No cell
communication