Technical Note: TN0045 - Rev 04

SP PRO Shunt Installation

The SP PRO accurately monitors current in and out of the battery bank to keep track of the battery bank's State of Charge (SoC). The SP PRO internally measures any current flow to and from the battery caused by the SP PRO itself, but requires additional external current shunts to measure other connected components like solar input via a DC charge controller/regulator or DC loads. The SP PRO has two shunt sense inputs for this purpose.


Shunt Wiring

External shunts to measure current flow to a DC load or current flow into the battery bank from a charge controller MUST be installed between the load or charge controller/regulator and the main battery negative terminal as shown below, and NOT between the SP PRO and the battery negative terminal.

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NOTE: Shunts installed in any other position will not operate correctly and may cause damage to the SP PRO.

Shunt Sense Wiring Polarity

Polarity is important when using the shunt in “Dual” or “Multiple SP PRO” mode, that is, where the shunt is used for both input and output measurement to obtain a net result. In this case, the sense wiring MUST be wired as shown above – 1A or 2A terminal in the expansion card connects to the solar and load side, 1B or 2B connects to the battery negative side.

NOTES for SP Link:

  • In “Dual” or “Multiple SP PRO” mode, shunt currents are displayed with a sign: a positive (+) number means charging and a negative (-) number means discharging.
  • The polarity of these shunt sense leads is not important if they are configured to either “Load” or any of the input selections, such as “Solar”.

SP PRO Configuration

The SP PRO by default ignores any input from the shunts. Please consult the SP PRO User Manual for configuration and zeroing of the shunts.

Additional Information

Selectronic web site: or contact the Selectronic Sales Team.


 Check Shunt configuration
Check that shunt configuration in SP Link matches actual rating of shunt installed (rating is imprinted on shunt)
 Zero shunt
Zero shunt when shunt circuit is closed and complete but when no current is flowing, i.e. when solar is isolated from charge controller or DC load isolated
Additional Information
Visit the Selectronic: Knowledge Base or contact Selectronic via Customer Portal