Kelvin sensing

Example

Use in Lemonergy

Separate quantities from encoding and transport.

This is a reference concept. No executable Lemonergy block has been verified for this term.

Connected concepts

Related concepts from the knowledge graph. Connections show context, not cause and effect. Hover or focus a linked term for its definition.

Cell balancing

Equalising the state of charge of cells in series, since the pack is limited by its emptiest cell on discharge and its fullest on charge. Passive balancing bleeds charge from high cells through resistors; active balancing moves it between cells.

Electrical contact resistance

The extra resistance where two conductors touch, because current passes only through microscopic contact spots and any oxide film on them. It falls with contact force and good plating and rises with corrosion and fretting. At 300 A a joint of 50 µΩ dissipates 4.5 W, enough to overheat a poorly cooled connection.

Current sensor

The device that measures pack current for coulomb counting and protection: a precision shunt resistor read by an amplifier, or a Hall-effect sensor around the cable. Offset error in this sensor is what makes SOC drift between OCV corrections.

DC internal resistance

Internal resistance measured from the voltage change during a current pulse of defined length, usually 10 s or 18 s. It is larger than the AC value because it includes charge-transfer and some diffusion, and it depends on SOC, temperature and pulse duration.

Thermoelectric voltage error

A small voltage, the Seebeck effect, that appears wherever two different metals meet at different temperatures. Negligible for cell voltages, it matters for shunt current sensing: on a 100 µΩ shunt each microvolt reads as 10 mA, which coulomb counting integrates into SOC drift. Manganin is used for shunts partly because its thermal EMF against copper is under 1 µV/K.

Voltage sensing

Measuring each series cell group’s voltage through a wire or flexible circuit from its busbar to the monitoring chip. Millivolt accuracy matters because the BMS reads SOC and detects faults from these numbers.

References & further reading

Further reading on this topic

These sources provide broader context; they are not presented as citations for every statement in this entry.

1. 3rd generation of the CAN data link layer

   CAN in Automation, CAN Newsletter · 2020

   Topic background · Classical CAN, CAN FD and CAN XL data-link concepts; publication describes the 2020 state.

2. Getting Started with the BQ76925

   Texas Instruments · 2019

   Topic background · A concrete BMS analog front-end example: cell voltage, current, temperature measurement and MCU integration.