The current sensor should be sized to meet the highest amperage expected in an application.
While no longer as important with these higher accuracy current sensors, they should be sized as small as possible to improve accuracy. For example, if an application has an expected maximum amperage of 275 amps, a 500A current sensor should be used. Some headroom should be left between the maximum expected amperage and the size of the current sensor to allow for brief current transients that may exceed the rating of the current sensor. For example, if the application is expected to draw 190 amps maximum, a 500A current sensor should be selected even though a 200A sensor is technically large enough. While accuracy is somewhat improved by using the smallest current sensor for the application, it is best to error on the side of getting a sensor that is larger than necessary since the accuracy is not greatly improved.
The current sensor is technically optional, however it is strongly recommended because the majority of the Orion BMS systems’ features depend on having an accurate current sensor.
Without a current sensor, the Orion BMS is unable to provide any of the following calculations:
● Internal resistance calculations
● Battery health monitoring
● Over-current protection (still provides over and under voltage protection)
● Current measurements
● Open cell voltage calculation
● Weak cell faults
● State of charge calculation or state of charge drift
● Calculation of Charge or Discharge current limits