Battery knowledge · Units and electrical basics
Voltage
The potential difference between a cell’s two terminals. It comes from the chemical difference between the electrodes, moves with state of charge, and sags under load because of internal resistance. [1]
- Also called
- terminal voltage
- Unit
- V
Example
Voltage under load
5 A through 20 mΩ gives 0.1 V ohmic drop.
Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.
Explore the graph
Discharge current creates an ohmic drop below open-circuit voltage.
5 A through 20 mΩ gives 0.1 V ohmic drop.
V_terminal = OCV − I_discharge R
Illustrative model. Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.
Use in Lemonergy
Lemonergy Studio blocks
AC current source worked example
Analytic sinusoidal current, positive from p to n
Blocks to use
- AC current source
Conserving component solved simultaneously with the connected network. Analytic sinusoidal current, positive from p to n
Inputs & settings
- Use the block reference for settings and connections.
- Bundled example verified on the production release of 28 October 2026.
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Review the interface, units and model limits.
- Open the Studio example and run its bundled model.
- Compare outputs with the numerical checks; change one input and run again.
Example. Editable first-party network. load: resistanceOhm=4. Checks below were verified in the native execution engine.
Observe. Inspect the output channels and checks on the block reference page.
Analytic sinusoidal current, positive from p to n Demonstration parameters are not calibrated hardware data. Singular or incompatible ideal constraints and unsupported state ranges stop the run.
Open Studio example →Lemonergy Studio blocks
AC voltage source worked example
Analytic sinusoidal voltage p minus n
Blocks to use
- AC voltage source
Conserving component solved simultaneously with the connected network. Analytic sinusoidal voltage p minus n
Inputs & settings
- Use the block reference for settings and connections.
- Bundled example verified on the production release of 28 October 2026.
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Review the interface, units and model limits.
- Open the Studio example and run its bundled model.
- Compare outputs with the numerical checks; change one input and run again.
Example. Editable first-party network. load: resistanceOhm=4. Checks below were verified in the native execution engine.
Observe. Inspect the output channels and checks on the block reference page.
Analytic sinusoidal voltage p minus n Demonstration parameters are not calibrated hardware data. Singular or incompatible ideal constraints and unsupported state ranges stop the run.
Open Studio example →Lemonergy Studio blocks
Cell contact residual monitor worked example
Filters cell/group voltage residuals against their median and qualifies persistent differences. Residuals are not a unique contact-fault diagnosis.
Blocks to use
- Cell contact residual monitor
Forms measured-minus-predicted voltage residuals, subtracts their channel median, filters the differences and qualifies consecutive threshold crossings when current is large enough.
Inputs & settings
- Use the parameter values in the block reference.
- Bundled example verified on the production release of 28 October 2026.
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Review the block inputs, units and model limits.
- Open the Studio example and run its bundled model.
- Compare the output channels with the numerical checks; change one input and run again.
Example. Use the defaults below with Measured cell/group voltages = [3.64, 3.66, 3.66] V, Predicted healthy voltages = [3.66, 3.66, 3.66] V, Signed current = 2 A, Enable = 1 true / false. At 0 s, Filtered differential residual is [0, 0, 0] V. Additional checks are listed below.
Observe. Inspect the outputs and numerical checks on the block reference page.
Requires at least three channels. Contact loss, parameter mismatch and sensor bias can produce the same symptom; this is not a unique fault diagnosis. The example verifies numerical behavior for synthetic parameters. Cell characterization and validation for an intended use are separate tasks.
Open Studio example →Learn it in Lesson 1 · Cell anatomy →
All connected Lemonergy block references
- AC current source
- AC voltage source
- Cell contact residual monitor
- Battery current monitor
- Tabulated fuel-cell stack
- Battery temperature monitor
- Battery voltage monitor
- Current-controlled current source
- Piecewise-linear diode
- Electrical gyrator
- Controlled electrical switch
- Capacitive floating reference
- Ideal transformer
- Open branch with initial voltage target
- Ideal linear motor coupler
- Bounded drift memristor
- Coupled inductors
- Open electrical port
- Finite-gain operational amplifier
- Ideal rotational motor coupler
- Voltage-controlled current source
- Current-controlled voltage source
- Electromechanical variable-gap capacitor
- Controlled resistor
- Voltage-controlled voltage source
- Electrical reference
- Resistor
- Controlled voltage source
Studio interfaces connected to this concept
These components declare this quantity or operation. Their individual pages distinguish authoring metadata from numerical verification.
- AC current source
- AC voltage source
- Active cell supervision interface
- Multi-cell balancing interface
- CC-CV current controller
- Cell-delta SOC EKF
- Cell-delta SOC EKF with resistance input
- Charge-current envelope
- Cell contact residual monitor
- Controlled discharger
- Battery cycle program
- Discharge-current envelope
- Electrothermal ECM cell
- Tabulated fuel-cell stack
- Incremental CC-CV controller
- Battery module
- Module assembly
- Battery with SOC-dependent OCV
- Battery pack assembly
- Pack-average SOC adaptive EKF
- Pack-average SOC EKF
- Parallel cell group
- Passive cell balancer
- Reduced PEM fuel-cell stack
- Pulse power capability
- Single-particle cell
- SOC adaptive EKF
- SOC adaptive EKF with capacity input
- SOC EKF
- SOC EKF with capacity input
- SOE adaptive EKF
- SOE adaptive EKF with capacity input
- SOE EKF
- SOE EKF with capacity input
- Battery: resistance and charge state
- State-space impedance
- Supercapacitor cell
- Tabulated OCV cell
- Battery voltage monitor
- Bidirectional grid / load interface
- Capacitor
- Delayed contactor with declared fault mode
- Current-controlled current source
- Current sensor / signal adapter
- Controlled current source
- DC motor with shaft coupling
- Piecewise-linear diode
- Electrical gyrator
- Electrical reference
- Controlled electrical switch
- Independent electrothermal battery
- Electrothermal resistor
- Capacitive floating reference
- Ideal transformer
- Inductor
- Open branch with initial voltage target
- Ideal linear motor coupler
- Bounded drift memristor
- Coupled inductors
- Open electrical port
- Finite-gain operational amplifier
- SOC and temperature limited signed power boundary
- Passive cell supervision interface
- Limited P/V electrical load
- Regulated CC/CV charger
- Resistor
- Ideal rotational motor coupler
- Average bidirectional source converter
- Voltage-controlled current source
- Current-controlled voltage source
- Conserving vehicle-to-vehicle converter
- Electromechanical variable-gap capacitor
- Controlled resistor
- Voltage-controlled voltage source
- Voltage sensor / signal adapter
- Controlled voltage source
References & further reading
Technical references
- The International System of Units (SI), 9th edition
Bureau International des Poids et Mesures · 2026
Technical reference · Definitions of SI units and coherent derived units; 2026 revision.