JK BMS Settings for NMC and LTO: Safe Per-Cell Values
JK BMS settings for NMC and LTO differ from LiFePO4 mainly in voltage. NMC and NCA li-ion cells (3.6 to 3.7 V nominal) charge to at most 4.2 V and are happiest at 4.1 V or lower. LTO cells (2.3 to 2.4 V nominal) charge to at most 2.8 V, and they tolerate cold and fast charging far better than any other lithium chemistry.
How the editor picks the chemistry
JK Preset Studio looks at your Cell OVP and guesses the chemistry. The rule is simple:
- Cell OVP of 3.9 V or more: NMC.
- Cell OVP below 3.0 V: LTO.
- Anything in between (for example 3.65 V): LiFePO4.
The guess only chooses which recommended ranges to show, and you can change it by hand.
Why the top voltage matters for NMC
Li-ion cells age faster the higher the voltage they sit at. Charging to 4.1 V instead of 4.2 V gives up a small part of the capacity and improves cycle life noticeably. Battery University and Sandia ageing research both point this way. That is why the gentle NMC preset stops at 4.1 V Cell OVP and the hard one uses 4.2 V.
Why LTO is different
LTO cells do not plate lithium easily when charged cold, so many are rated to charge below 0 °C and the temperature limits are much wider than for NMC. They also tolerate deep cycling and high currents. Check your datasheet, because some cells are more conservative.
JK BMS settings for NMC and LTO per cell
All voltages are per cell. The three levels are the editor presets, and the ranges come from the editor's recommendations.
NMC values
Sources: Samsung 50E and LG M50LT datasheets, JK manuals, Battery University and Sandia.
| Parameter | Range | Hard | Medium | Gentle |
|---|---|---|---|---|
| Cell OVP | 4.10 to 4.20 V | 4.20 V | 4.15 V | 4.10 V |
| Cell OVP recovery | 3.90 to 4.10 V | 4.05 V | 4.00 V | 3.90 V |
| Cell UVP | 2.80 to 3.20 V | 2.80 V | 3.00 V | 3.20 V |
| Cell UVP recovery | 3.10 to 3.40 V | 3.10 V | 3.20 V | 3.40 V |
| Start balance voltage | 3.90 to 4.00 V | 3.90 V | 3.90 V | 3.90 V |
| Balance trigger voltage | 0.005 to 0.015 V | 0.010 V | 0.010 V | 0.010 V |
| SOC-100% voltage | 3.95 to 4.10 V | 4.10 V | 4.05 V | 3.95 V |
| SOC-0% voltage | 2.90 to 3.30 V | 2.90 V | 3.10 V | 3.30 V |
| Cell RCV | 4.00 to 4.15 V | 4.15 V | 4.10 V | 4.00 V |
| Cell RFV | 3.90 to 4.05 V | 4.05 V | 4.00 V | 3.90 V |
| Charge OTP | 40 to 45 °C | 45 °C | 43 °C | 40 °C |
| Charge UTP | 0 to 10 °C | 3 °C | 5 °C | 10 °C |
| Discharge UTP | -20 to -10 °C | -20 °C | -15 °C | -10 °C |
| Charge / discharge C-rate | none set | 0.7C / 1C | 0.5C / 0.7C | 0.3C / 0.5C |
LTO values
Sources: Yinlong and Toshiba SCiB data, JK manuals and the DIY Solar Forum. Several LTO ranges are community estimates, so check them against your cell datasheet.
| Parameter | Range | Hard | Medium | Gentle |
|---|---|---|---|---|
| Cell OVP | 2.60 to 2.80 V | 2.80 V | 2.70 V | 2.60 V |
| Cell OVP recovery | 2.35 to 2.65 V | 2.60 V | 2.50 V | 2.40 V |
| Cell UVP | 1.70 to 1.90 V | 1.70 V | 1.80 V | 1.90 V |
| Cell UVP recovery | 1.95 to 2.05 V | 1.95 V | 2.00 V | 2.05 V |
| Start balance voltage | 2.40 to 2.50 V | 2.45 V | 2.40 V | 2.40 V |
| Balance trigger voltage | 0.005 to 0.015 V | 0.010 V | 0.010 V | 0.010 V |
| SOC-100% voltage | 2.45 to 2.65 V | 2.65 V | 2.55 V | 2.45 V |
| SOC-0% voltage | 1.80 to 2.00 V | 1.80 V | 1.90 V | 2.00 V |
| Cell RCV | 2.50 to 2.70 V | 2.70 V | 2.60 V | 2.50 V |
| Cell RFV | 2.40 to 2.60 V | 2.60 V | 2.50 V | 2.40 V |
| Charge OTP | 45 to 55 °C | 55 °C | 50 °C | 45 °C |
| Charge UTP | -30 to -5 °C | -25 °C | -15 °C | -5 °C |
| Discharge UTP | -40 to -30 °C | -35 °C | -30 °C | -30 °C |
| Charge / discharge C-rate | none set | 3C / 3C | 2C / 2C | 1C / 1C |
Balancing on NMC and LTO
The voltage curve of NMC and LTO is steeper than LiFePO4, so a small difference in charge shows up as a clear voltage difference over a wide range. The presets start at 3.9 V for NMC and 2.4 to 2.45 V for LTO, with a trigger of 0.010 V. See JK BMS balance settings for how the start voltage, trigger and balance current work together.
Pack voltage and cell count
Multiply every per-cell value by the cell count to get the pack value. Common NMC builds are 7S (29.4 V full), 13S (54.6 V) and 14S (58.8 V). A 6S LTO pack reaches 16.8 V at 2.8 V per cell. A 14S NMC pack at 4.2 V per cell can be above the input limit of some 48 V equipment, so set Cell OVP to keep the pack inside what the charger accepts, and set the Cell count to match your pack.
The firmware chains still apply
The JK firmware checks the same order on every chemistry: Cell OVP recovery below SOC-100% voltage below Cell RCV, and Cell UVP below SOC-0% voltage below Cell UVP recovery. Equal values are rejected. All presets above follow these chains. If you edit single values by hand, keep the order or the BMS answers "This parameter does not apply to the connected device. (Sending failure)". See JK BMS sending failure for the fix.
Common mistakes and FAQ
Can I use LiFePO4 settings on NMC cells?
No. A Cell OVP of 3.65 V leaves an NMC cell well short of full, and a UVP of 2.5 V is below the safe limit for many NMC cells. Compare with the LiFePO4 settings to see the difference.
What are good JK BMS 18650 settings?
18650 and 21700 cells are usually NMC or NCA, so use the NMC table. Check the datasheet for exact limits, and set Max charge current from the C-rate and pack capacity.
Can I charge LTO below freezing?
Many LTO cells can, but confirm the lower limit in your datasheet. Never copy an LTO charge UTP onto NMC cells.
Every parameter is described in the parameter reference. Open the presets page for one-click NMC and LTO presets, then connect your BMS or open your .jkcfg in the editor to apply them, check the result and write it back.
Related guides
- JK BMS Settings for LiFePO4: 8S and 16S, 280Ah and 314AhJK BMS settings for LiFePO4 packs: per-cell voltage, balance, current and temperature values for 8S and 16S with 280Ah and 314Ah cells, in three wear levels.
- JK BMS Parameters Explained: Every Setting by GroupJK BMS parameters explained in one glossary: cell OVP, OVPR, UVP, UVPR, balance, SOC, RCV and RFV, current and temperature limits, with typical LFP ranges.
- JK BMS Balance Settings: Start Voltage, Trigger, CurrentJK BMS balance settings explained: start balance voltage, balance trigger voltage, max balance current and the Balancer switch, for LFP, NMC and LTO.