Battery knowledge · Modules, packs and battery management

Fuel gauge

The single chip in a phone, laptop or power tool that does the BMS’s state-estimation job for one or a few cells: coulomb counting corrected by an OCV model, with impedance tracking in better parts. It reports remaining capacity over SMBus or I²C.

Also called
gas gauge

Example

Charge balance and state of charge

From 20% SOC, ideal full charge takes 48 min. Integration stops at 100%.

Current is positive into the cell. Constant capacity and 100% charge efficiency; no CC-CV taper.

Explore the graph

SOC rises with accumulated charge; depth of discharge falls by the same amount.

Complementary charge fractions
Complementary charge fractionsTime (h) versus Capacity fraction (%). SOC; DOD. Interpretation follows the graphs.002515027531004Time (h)Capacity fraction (%)
SOCDOD (dashed)

From 20% SOC, ideal full charge takes 48 min. Integration stops at 100%.

SOC = SOC₀ + ∫ I_charge dt / Q; DOD = 1 − SOC

Illustrative model. Current is positive into the cell. Constant capacity and 100% charge efficiency; no CC-CV taper.

Use in Lemonergy

Make series/parallel architecture explicit.

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

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. Extended Kalman filtering for battery management systems of LiPB-based HEV battery packs: Part 2. Modeling and identification

    Gregory L. Plett · Journal of Power Sources · 2004

    Topic background · Battery charge balance, open-circuit voltage, ohmic loss, polarization dynamics and model identification; parameters require cell-specific data.

  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.