Battery knowledge · Modules, packs and battery management
Derating
Reducing the allowed charge or discharge power as the battery approaches a limit — low temperature, high temperature, high or low SOC, or age. It is how a BMS keeps the cells safe while letting the vehicle do as much as it can.
Example
The limit sets the permitted current
Requested current: 8 A. At 50 °C the chosen limit permits 5 A.
Breakpoints are invented teaching values, not operating limits for a particular battery.
Explore the graph
A requested current is clipped wherever an active limit is lower.
Requested current: 8 A. At 50 °C the chosen limit permits 5 A.
I_command = min(I_requested, I_limit)
Illustrative model. Breakpoints are invented teaching values, not operating limits for a particular battery.
Use in Lemonergy
Design protocol or analysis tool
Stop at a declared limit
A discharge can end at temperature or voltage thresholds.
Equation or tool to use
- Discharge with ending condition
Stops at threshold
Inputs & settings
- mode: cc
- until: tC or vCell
- Maximum duration
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
Example. The template uses 30 A, 1800 s maximum, 45 °C and a 3.0 V cell floor to illustrate stopping.
Observe. A threshold can end the run early.
This simulated screen is not abuse testing or proof that the battery or protection system is safe.
Open Design → Protocol bench →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.
- 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.
- 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.