Voltage reading differential during charge (Blue Smart IP67 12/25 high voltage reading)

[abeness]

My Blue Smart IP67 12/25 charger consistently reads approximately 0.58V-0.65V higher than my BMV-712 in the app, during charge. For example, when the BMV-712 reads 13.55V, the BatteryProtect 100A reads 14.02V, and the charger shows 14.13V to 14.20V (fluctuating up and down, while the BMV and BP remain constant at their respective readings).

The charger positive is connected to the IN post of the BP per specifications, and the charger negative is connected to a negative busbar after a 4-inch 6 AWG hop from the shunt, so voltage drop should not be an issue. Primary wiring in this 230Ah battery box build is 1/0 AWG, and short.

Is this expected Blue Smart IP67 12/25 behavior during charge? FW 3.65. Voltage appears to be consistent during discharge. I don’t believe the odd higher reading is leading to premature charge status change.

Screenshots:

[pwfarnell]

The biggest voltage drop is from your Battery Protect to the battery, not from the charger to Battery Protect so your voltage drop is in your wiring / fusing / breakers in that location. Use a multimeter to check voltage at each connection to.find the voltage drop.