The current sensor should be sized to meet the highest amperage expected in an application, however 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 err on the side of getting a sensor that is larger than necessary since the accuracy is not greatly improved.
The current sensors offered with the Orion BMS are dual range sensors and contain 2 sensors in each package. One sensor is smaller than the other and this is used to provide both redundancy and to improve accuracy measuring smaller currents. The following sizes of current sensors are currently available: +/- 350A, 500A, 800A, 1000A.
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
● Over-current protection (still provides over and under voltage protection)
● Current measurements
● Open cell voltages
● Weak cell faults
● State of charge calculation or state of charge drift
● Calculation of Charge or Discharge current limits
● Simulation of virtual battery