Calculator inputs
Enter pack voltage, current, resistance values, operating temperature, and time. The calculator applies resistance temperature adjustment, loss distribution, and energy waste estimation.
Example data table
These sample cases show how current, resistance, temperature, and duty cycle shape voltage drop and wasted power across different pack conditions.
| Scenario | Voltage | Current | Total Adjusted Resistance | Total Voltage Drop | Instantaneous Loss | Efficiency |
|---|---|---|---|---|---|---|
| Light DC Load | 12.00 V | 8.00 A | 56.073 mΩ | 0.4486 V | 3.5886 W | 96.26 % |
| Industrial Controller | 24.00 V | 15.00 A | 42.340 mΩ | 0.6351 V | 9.5265 W | 97.35 % |
| Mobility Pack | 48.00 V | 30.00 A | 29.106 mΩ | 0.8732 V | 26.1954 W | 98.18 % |
| High Current Test | 72.00 V | 45.00 A | 21.223 mΩ | 0.9550 V | 42.9766 W | 98.67 % |
Formula used
The calculator combines base resistance values, temperature adjustment, power loss, voltage drop, duty cycle, and energy waste into one engineering view.
-
Temperature-adjusted resistance
Radjusted = Rbase × (1 + α × (Top - Tref))
Here, α is the temperature coefficient, Top is operating temperature, and Tref is the reference temperature. -
Total resistance
Rtotal = Rinternal + Rcable + Rcontact -
Voltage drop
Vdrop = I × R
The tool calculates each path separately, then adds them for total voltage sag. -
Instantaneous power loss
Ploss = I² × R
This is the heat being generated in resistive elements while current is flowing. -
Delivered load voltage and power
Vload = Vnominal - Vdrop,total
Pdelivered = Vload × I -
Average loss and energy waste
Pavg loss = Ploss,total × Duty Fraction
Energy loss = Pavg loss × Operating Hours
How to use this calculator
- Enter the pack’s nominal voltage and expected operating current.
- Add measured or estimated internal, cable, and contact resistance values in milliohms.
- Set duty cycle and operating time to convert instantaneous loss into average waste and energy loss.
- Enter operating and reference temperatures if resistance changes with temperature matter in your design.
- Optionally provide battery capacity and electricity price for discharge and cost estimates.
- Press calculate to view resistance breakdown, voltage sag, efficiency, exported results, and the Plotly comparison graph above the form.
Frequently asked questions
1) What does battery power loss mean?
Battery power loss is the portion of electrical input converted into heat inside internal resistance, cables, and contact points instead of reaching the load.
2) Why is internal resistance important?
Internal resistance directly raises voltage drop and heat generation as current increases. Even small milliohm changes can materially affect pack efficiency at higher loads.
3) Why include cable and contact resistance?
Losses do not occur only inside cells. Wiring length, connector quality, busbars, crimps, and terminals can add measurable resistance and increase wasted power.
4) What does duty cycle change in the results?
Duty cycle scales instantaneous loss into average power loss and total energy waste over time. It helps represent pulsed or intermittent operation more realistically.
5) Why does temperature matter here?
Many conductive materials rise in resistance with temperature. Higher operating temperature can therefore raise voltage sag, power loss, and total heat during the same current draw.
6) Is voltage drop the same as power loss?
No. Voltage drop is the reduction in available load voltage. Power loss is the heat created by that resistance under current, calculated with current squared times resistance.
7) What efficiency level is usually acceptable?
That depends on the application. Sensitive electronics, mobility systems, and thermal-limited enclosures often need tighter loss control than lightly loaded backup systems.
8) Can I use this for any battery chemistry?
Yes, as long as your voltage, current, resistance, and temperature assumptions are realistic. The method is electrical, not chemistry-specific, though resistance values differ by chemistry.