Battery knowledge · Modules, packs and battery management
DC/DC converter
The power electronics that step the high-voltage pack down to 12 V or 48 V for the auxiliary systems, replacing the alternator of a combustion car. Boost converters also appear between an 800 V pack and a 400 V charger.
Example
Duty cycle controls average voltage
50% of 12 V gives a 6 V time average.
Unfiltered ideal waveform; actual output depends on the converter circuit and control.
Explore the graph
An ideal pulse train alternates between zero and the supply voltage.
50% of 12 V gives a 6 V time average.
V_average = D V_supply
Illustrative model. Unfiltered ideal waveform; actual output depends on the converter circuit and control.
Use in Lemonergy
Lemonergy Studio blocks
Transfer between two batteries
Conserving conversion couples donor and recipient.
Blocks to use
- Battery with SOC-dependent OCV
Stores charge and supplies terminal voltage
Inputs & settings
- capacityAh
- initialSoc
- emptyVoltageV / fullVoltageV
- resistanceOhm
- Electrical ports p and n
- Conserving vehicle-to-vehicle converter
Enforces both batteries’ limits
Inputs & settings
- donorP / donorN
- recipientP / recipientN
- donorReserveSoc / recipientTargetSoc
- efficiency
- Battery with SOC-dependent OCV
Stores charge and supplies terminal voltage
Inputs & settings
- capacityAh
- initialSoc
- emptyVoltageV / fullVoltageV
- resistanceOhm
- Electrical ports p and n
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Inspect donor reserve and recipient target.
- Compare energy drawn and delivered.
Example. 5 kW delivered at 90% efficiency needs about 5.56 kW from the donor and produces about 0.56 kW loss.
Observe. Both islands have references and energy flows.
The example assumes hardware compatibility; it does not establish connector or communication compatibility.
Open the Studio example →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.