Split pack

Example

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Use in Lemonergy

Make series/parallel architecture explicit.

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

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Battery disconnect unit

The box inside the pack that holds the contactors, pre-charge circuit, main fuse or pyrofuse and current sensor, where the pack’s high-voltage connections are made and broken.

Contactor

A heavy-duty electrically operated switch that connects the pack to the vehicle or inverter and opens it on fault or shutdown. Packs use at least two, one per pole, plus a pre-charge path to avoid welding them on the first connection.

DC fast charging

Charging from a station that supplies DC straight to the pack, bypassing the car’s onboard charger, at 50 kW to over 350 kW. The BMS, not the charger, sets the current from moment to moment, which is why the charge curve tapers as the pack fills.

Pack voltage

The nominal voltage of the full series string, about 400 V in most electric cars and 800 V in newer ones. Doubling the voltage halves the current for the same power, so cables, connectors and losses shrink and charging can be faster.

Series and parallel connection

Cells in series add their voltages; cells in parallel add their capacities and share current. A pack is described as, for example, 96s4p: 96 groups in series, each of 4 cells in parallel. Series strings need balancing; parallel groups self-balance through their shared terminals.

Split-pack charging

Reconfiguring a pack with contactors so that its two halves charge in parallel at half the drive voltage. An 800 V vehicle such as the Tesla Cybertruck can then use 400 V fast chargers without a DC/DC booster; GM’s Hummer EV does the reverse, driving at 400 V and switching the halves into series to charge at 800 V.

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.