https://community.victronenergy.com/t/where-is-the-jk-bms-cvl-value-originating-from/33010/10

https://www.youtube.com/watch?v=OpEQ4fV7-ZU

55.2volt

53.6 float

Andy shares detailed configuration settings for his LiFePO₄ battery system, using Victron equipment, JK-BMS, and the VE.Smart Network. Below are his recommended values and how he applies them.

• Absorption voltage: '3.45 V per cell' (≈13.8 V for 4S, ≈55.2 V for 16S)
• Absorption duration: '~1 hour'
• Float voltage: '3.35 V per cell' (≈13.4 V for 4S, ≈53.6 V for 16S)
• Re-bulk trigger: 'Float voltage − 0.1 V' (e.g., 13.3 V or 53.5 V)
• Smart Networking: Uses 'VE.Smart Network' to synchronize charger and shunt

• Same absorption target: '3.45 V per cell'
• Communicates with Victron via DVCC / RS485 (when available)
• No float needed on BMS — voltage is managed via charge source

To detect 100% SOC accurately:

1. Battery must reach 'absorption voltage'
2. Current must fall below the 'tail current' threshold
3. Voltage and current must meet conditions for a set 'charge detection time'

This ensures the shunt resets SOC to 100% correctly.

To apply this to a 48 V (16S) system, just multiply by 4:

• 3.45 V × 16 = '55.2 V' Absorption
• 3.35 V × 16 = '53.6 V' Float

• '3.45 V/cell absorption' ensures full charge and BMS balancing
• 'Float at 3.35 V/cell' avoids overcharging while keeping the system full
• 'Re-bulk at float minus 0.1 V' ensures charging resumes under load or SOC drop
• Maximizes solar energy usage during partial loads or clouds

1. Set absorption to '3.45 V per cell' and ~1 hour duration
2. Set float to '3.35 V per cell'
3. In Victron Expert Settings, set re-bulk trigger to '−0.1 V'
4. Enable 'VE.Smart Network / DVCC' between charger, BMS, and shunt
5. Configure Smart Shunt charge detection:
   1. Absorption voltage threshold
   2. Tail current threshold
   3. Charge detection duration
6. Scale voltages to match total series cell count

Let me know if you want a ready-to-use config file or screenshots for Victron SmartSolar or JK-BMS!

Andy from Off‑Grid‑Garage recommends the following voltage settings for a 12 V (4S) LiFePO₄ battery system. These values can be scaled for larger battery banks.

• Absorption voltage: '13.6 V' (≈ 3.4 V per cell)
• Float voltage: '13.6 V' (maintains charge without stress)
• Re‑bulk trigger: about '0.1 V below float' (≈13.5 V)

This means:

• Charge until the pack reaches 13.6 V
• Hold (absorption) until current tapers off (tail current)
• Maintain (float) at 13.6 V
• Resume charging when voltage drops to 13.5 V

• 3.4 V per cell allows the BMS to balance cells without overcharging
• Using the same value for absorption and float simplifies the process
• This setup is ideal for daily cycling and prolongs battery life

For a 48 V (16S) LiFePO₄ system:

• Absorption & Float voltage = '54.4 V' (3.4 V × 16)
• Re-bulk trigger = around '54.0 V' (≈ 0.1 V per cell lower)
• Tail current cutoff depends on charger/BMS settings

To apply these values to your specific system, just scale based on the number of cells in series (S).

Below are two ready-to-load profiles:

•	Daily / long-life – keeps you at ≈ 90 % usable capacity for maximal cycle life.
•	Full-capacity / top-balance – run only when you need every last Wh or to re-sync SOC.

•	Daily – leave the inverter/charger at the “Daily” limits for routine cycling (≈ 13–14 kWh usable).
•	Monthly or after maintenance – switch to “Full-capacity”, let it absorb until tail-current ≤ 0.02 C and balancer quits, then drop back to “Daily”.

•	Keep charge/discharge ≤ 0.5 C (≈ 140 A) for longevity, even though the V4 / V5 rack can tolerate short peaks.
•	Balancing only becomes effective above ≈ 3.45 V / cell.
•	Verify every sense lead and bus-bar is tight—loose sense wires can spoof the JK-BMS into false OVP trips.

•	Cell specs: 3.65 V max / 2.50 V min per LF280K cell.
•	Longevity studies: best life around 3.45–3.50 V / cell.
•	JK-BMS best practice: 3.55 V OVP with 0.1 V total hysteresis is the community standard.

These numbers line up with the two battery profiles I gave earlier. Use VE.Configure or VictronConnect → “Inverter/Charger settings” and enter the values exactly. All voltages below are battery-side (48 V nominal).

Disable Equalise, Weak-AC, and Bulk-time limit.

•	AC Input current limit – match your feeder breaker: e.g. 25 A for a 6 kW circuit.
•	Power-Assist – leave ON (default).
•	UPS mode – leave ON unless your loads can tolerate a short break.

If you bridge the JK-BMS CAN port to VE.Can (or run Node-RED/Can-to-VE.Bus), enable DVCC on the GX device. The JK will then push live max-charge Voltage & Current, overriding the fixed numbers above during faults or cold temps.

•	Daily use – keep the charger on the “Daily” voltages.
•	Once a month – switch to the “Full-capacity” preset, start a Forced Absorption (VE.Configure → “Charger” → Start forced absorption), wait until tail current ≤ 0 .02 C and the JK balancer is quiet, then revert to “Daily”.

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•	Long-life profile
•	12.6 kWh × ≈ 10 000 cycles ≈ 126 MWh delivered
•	Full-capacity profile
•	14 kWh × ≈ 6 000 cycles ≈ 84 MWh delivered

Limiting the top charge sacrifices ~10 % each cycle but delivers ≈ 50 % more total energy over the pack’s life.

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•	Stay in long-life mode for routine cycling (solar ESS, backup, RV, boat).
•	Once a month or before a deep discharge
•	switch charger/BMS to the full-capacity preset,
•	absorb until tail current ≤ 0.02 C and the JK balancer is quiet,
•	then revert to long-life settings.
•	Avoid leaving the pack at 100 % SoC for more than a few hours; high-voltage storage ages LFP faster than cycling.

With this regime your LF280K rack can realistically exceed 100 MWh of delivered energy and still retain > 80 % capacity after a decade—far better than an always-full strategy.