Advanced LiPo Voltage Cutoff Calculator

Calculator Inputs

Use the grid below. Large screens show three columns, smaller screens show two, and mobile shows one.

White theme • Single-column page

Chemistry Preset

Series Cell Count

Capacity (mAh)

C Rating

Current Draw (A)

Cell Internal Resistance (mΩ)

Full Voltage Per Cell (V)

Nominal Voltage Per Cell (V)

Storage Voltage Per Cell (V)

Soft Cutoff Per Cell (V)

Hard Cutoff Per Cell (V)

Example Data Table

These sample pack values use a soft cutoff of 3.50 V per cell and a hard cutoff of 3.30 V per cell.

Pack	Capacity (mAh)	C Rating	Soft Cutoff / Cell (V)	Hard Cutoff / Cell (V)	Soft Pack Cutoff (V)	Hard Pack Cutoff (V)
2S	850	45	3.50	3.30	7.00	6.60
3S	1300	75	3.50	3.30	10.50	9.90
4S	2200	35	3.50	3.30	14.00	13.20
6S	5000	50	3.50	3.30	21.00	19.80
8S	7000	35	3.50	3.30	28.00	26.40

Formula Used

1) Pack voltage from per-cell voltage
Pack Voltage = Series Cell Count × Per-Cell Voltage

2) Maximum continuous current
Max Continuous Current = Capacity (Ah) × C Rating

3) Total pack resistance
Pack Resistance = Cell Resistance × Series Cell Count

4) Voltage sag under load
Voltage Sag = Current Draw × Pack Resistance

5) Loaded cutoff estimate
Loaded Cutoff = Resting Cutoff − Voltage Sag

6) Nominal energy estimate
Energy (Wh) = Nominal Pack Voltage × Capacity (Ah)

How to Use This Calculator

Select a chemistry preset or keep a custom profile.
Enter the series cell count for your battery pack.
Add capacity, C rating, expected current draw, and cell resistance.
Choose soft and hard per-cell cutoff levels.
Submit the form to show results above the calculator.
Review pack limits, sag, current margin, and the plotted discharge view.
Export the computed results as CSV or PDF.
Use conservative settings when your load is heavy or temperatures are high.

FAQs

1) What is a safe LiPo cutoff voltage?

A common conservative range is 3.4 to 3.6 volts per cell under light to moderate use. Many users avoid going below 3.3 volts per cell resting voltage to help preserve battery life.

2) Why does loaded voltage look lower than resting voltage?

Current draw causes voltage sag across the pack’s internal resistance. The harder the load, the larger the drop. Resting voltage usually rebounds after the throttle is reduced or the pack is disconnected.

3) Should I use soft cutoff or hard cutoff?

Use soft cutoff as your regular operating target. It gives you a safety margin and reduces stress. Hard cutoff is better treated as an emergency minimum, not a routine stopping point.

4) What does C rating change in this calculator?

C rating helps estimate the pack’s theoretical continuous current output. Comparing current draw to that value shows whether your load is modest, moderate, or aggressive for the chosen battery.

5) Why include internal resistance?

Internal resistance strongly influences voltage sag. Older, colder, or lower-quality packs often show higher resistance, so their loaded voltage can hit cutoff sooner than fresh packs with the same nominal rating.

6) Is storage voltage the same as cutoff voltage?

No. Storage voltage is a mid-level resting charge target for safer long-term storage. Cutoff voltage is the lower operating limit used to avoid excessive discharge while the pack is in service.

7) Can I use this page for LiHV or Li-ion packs?

Yes. The preset menu can load common voltage profiles for LiHV and Li-ion cells. You can also switch to custom mode and type your own per-cell values.

8) Does this calculator replace a battery analyzer?

No. It gives planning estimates based on the values you enter. Real pack behavior also depends on temperature, age, balance, wiring losses, and how accurately the device measures voltage.