JK BMS settings for LiFePO4

What each setting does

Cell OVP

Highest voltage a cell may reach: above it, the BMS stops charging.

Cell OVPR

Charging is allowed again once every cell is back under this voltage.

Start Balance Vol.

The balancer only works above this cell voltage, where voltage really reflects the charge.

Balance Trig. Volt.

Gap between the highest and lowest cell that wakes the balancer up.

Cell RCV

Charge voltage per cell that the BMS asks the inverter for.

Cell RFV

Float voltage per cell that the BMS asks for once the pack is full.

SOC-100% Volt.

Cell voltage at which the BMS sets its charge counter to 100 %.

SOC-0% Volt.

Cell voltage at which the BMS sets its charge counter to 0 %.

Cell UVPR

Discharge is allowed again once every cell is back above this voltage.

Cell UVP

Lowest voltage a cell may reach: below it, the BMS stops discharging.

Power Off Vol.

Below this, the board switches itself off to protect the cells from a deep discharge.

Charge OTP

Charging stops above this temperature.

Charge UTP

Charging stops below this temperature: LiFePO4 must never be charged below 0 °C.

Discharge OTP

Discharge stops above this temperature.

MOS OTP

The board protects its own power switches above this temperature. Keep the board default unless you know why.

Continued Charge Curr.

Highest charge current the BMS accepts for long. Half the cell capacity (0.5C) is the usual ceiling for LiFePO4, within the BMS rating.

Continued Discharge Curr.

Highest discharge current for long periods: up to 1C for most cells, but never above what the BMS and your cables are rated for.

Max Balance Cur.

Leave it at the maximum of your board (the figure before the A in the model name): the balancer only uses it when the gap is large.

Three mistakes we often see

• RCV at or below the balance start voltage. The inverter stops charging before any cell reaches the start voltage, so the active balancer never runs and the cells slowly drift apart.
• Balance start voltage set very low. On the flat part of the LiFePO4 curve, a few millivolts say almost nothing about charge: the balancer may move energy the wrong way.
• Charge allowed below 0 °C. Charging LiFePO4 in freezing conditions plates lithium and damages the cells for good. Keep Charge UTP above zero.

JK BMS Monitor reads these settings from your board and checks them against the same ranges, then shows any point to review on the dashboard. See it in the demo →

Starting points, not a guarantee: cell makers differ and the datasheet of your cells always comes first. JK BMS Monitor never writes settings; you change them in the JK app.