Cell Voltage limitation

[DirkReudenbach]

Hi mr-manuel,

in general i like the idea with the i or p controller but is it possible to switch off the Cell Voltage limitation?

[mdkeil]

If we mean the same thing then yes

; Charge current control management referring to cell-voltage enable (True/False).
CCCM_CV_ENABLE = True
; Discharge current control management referring to cell-voltage enable (True/False).
DCCM_CV_ENABLE = True

[DirkReudenbach]

sorry no I mean this part

; --------- Cell Voltage limitation (affecting CVL) ---------
; This function prevents a bad balanced battery to overcharge the cell with the highest voltage and the bms to
; switch off because of overvoltage of this cell.
;
; Example:
; 15 cells are at 3.4v, 1 cell is at 3.6v. Total voltage of battery is 54.6v and the Victron System sees no reason to
; lower the charging current as the control_voltage (Absorbtion Voltage) ist 55.2v
; In this case the Cell Voltage limitation kicks in and lowers the control_voltage to keep it close to the MAX_CELL_VOLTAGE.
;
; In theory this can also be done with CCL, but doing it with CVL has 2 advantages:
; - In a well balanced system the current can be kept quite high till the end of charge by using MAX_CELL_VOLTAGE for charging.
; - In systems with MPPTs and DC-feed-in activated the victron systems do not respect CCL, so CVL is the only way to prevent the
; highest cell in a bad balanced system from overcharging.
;
; There are 2 methods implemented to calculate CVL:
; 1. penalty_sum-Method (CVL_ICONTROLLER_MODE = False)
; The voltage-overshoot of all cells that exceed MAX_CELL_VOLTAGE is summed up and the control voltage is lowered by this "penalty_sum".
; This is calculated every LINEAR_RECALCULATION_EVERY seconds.
; In fact, this is a P-Controller.
; 2. I-Controller (CVL_ICONTROLLER_MODE = True)
; An I-Controller tries to control the voltage of the highest cell to MAX_CELL_VOLTAGE + CELL_VOLTAGE_DIFF_KEEP_MAX_VOLTAGE_UNTIL.
; (for example 3.45V+0.01V =3.46V). If the voltage of the highest cell is above this level, CVL is reduced. If the voltage is below, CVL is
; increased until cellcount*MAX_CELL_VOLTAGE.
; An I-Part of 0.2 V/Vs (CVL_ICONTROLLER_FACTOR) has proved to be a stable and fast controlling-behaviour.
; This method is not as fast as the penalty_sum-Method but usually smoother and more stable against toggeling and has no stationary deviation.
; More info: #882
CVL_ICONTROLLER_MODE = True
CVL_ICONTROLLER_FACTOR = 0.2

[cflenker]

You can switch this functionality off by setting CVL_ICONTROLLER_FACTOR to zero. But this means that you only have an overcharging protection for bad balanced batteries by CCL and that only works if you do not have a MPPT. Of cause the BMS will detect a single cell overvoltage and will disconnect. But this should only be the 'last line of defence'.

[DirkReudenbach]

ok thx for the detailed informations which I'd like to use for test purposes