Battery Capacity Calculation

Battery capacity is determined by summing the amp-hour (Ah) ratings of all parallel strings. For instance, two 100Ah batteries connected in parallel total 200Ah. Note that while series connections increase voltage, they do not affect amp-hour capacities.

Charged Voltage: 13.8V

Charged voltage should not be confused with absorption or charging voltage. It represents the voltage level at which the shunt deems the battery nearly fully charged, initiating current drop detection indicative of a full charge. Victron recommends setting this voltage 0.2V below the absorption voltage. Although suitable for most lead-acid batteries, this setting is suboptimal for SOK Lithium batteries as it may prevent the shunt from detecting true full charge conditions.

Tail Current: 2.00%

Once the charged voltage is reached, the current must taper down to this percentage to trigger synchronization. Testing confirms that Victron’s default setting effectively detects full charge status.

Charged Detection Time: 3 Minutes

In conjunction with charged voltage and tail current, this setting determines how long to wait after reaching the tail current set-point before confirming that the drop isn’t transient and the battery is indeed fully charged.

Peukert Exponent & Charge Efficiency Factor: 1.05 and 98% Respectively

These are fixed values reflecting inherent battery characteristics, requiring no adjustments.

Current Threshold: 0.10A

This is the minimum current the shunt is capable of detecting, independent of the battery’s characteristics.

Time to Go Averaging Period: 3 Minutes

This setting determines the frequency at which the time-to-go readout is recalculated, having no direct impact on battery performance.

Discharge Floor: Adjustable (10% Recommended)

You can adjust this setting based on your preference for remaining battery life indication. Setting this to 10% means the Smartshunt will display 10% remaining and 0 minutes until empty at this level. For a more conservative estimate, consider setting it higher.

Battery Starts Synchronized: Disabled

This setting affects only the SmartShunt and BMV-712. Enabling it resets the state of charge (SOC%) to 100% after power loss, potentially causing confusion since a depleted battery cannot reach 100% immediately upon recharging.

State of Charge: Not Changeable?

This is a manual override for the SOC%. Typically, new batteries ship at approximately 30% charge due to DOT regulations.