18650 series-parallel battery-pack co-design grammar

A constrained grammar for repositioning 18650 cells and editing whole series stages or parallel branches in a rectangular SxP battery pack.

See Grammar Problem Catalog for the grammar family index.

Quick Facts

Field	Value
Problem ID	battery_pack_18650_series_parallel
Problem Family	grammar
Implementation	design_research_problems.problems.grammar._battery_pack_sp:BatteryPack18650SeriesParallelProblem
Capabilities	discrete-actions, external-adapter, optional-evaluator, serializable-state, statement-markdown
Study Suitability	none
Tags	grammar, battery, series-parallel, layout, co-design

Taxonomy

Formulation

discrete_grammar

Convexity

not_applicable

Design Variable Type

discrete

Is Dynamic

no

Orientation

engineering_practical

Feasibility Ratio Hint

0.1

Objective Mode

multi

Constraint Nature

hard

Bounds Summary

explicit 3D cell coordinates inside a fixed envelope with a complete SxP topology

Tags

grammar, battery, series-parallel, layout, co-design

Statement

Design a battery pack using 18650 cells under a constrained series-parallel topology. The pack always forms a complete rectangular grid of logical electrical slots: S series stages by P parallel branches, with exactly one physical cell per slot. Designers may reposition cells in space, add a full new series stage, remove the final series stage, add a full new parallel branch, or remove the final parallel branch.

The benchmark target is a 14.8V pack with at least 10Ah capacity and at least 60A continuous current, under a 500mm x 500mm x 250mm envelope. Evaluation uses deterministic geometry and coarse thermal checks plus an optional PyBaMM-backed representative-cell discharge simulation.

Problem Shape

Field	Value
State Type	SeriesParallelBatteryState
Initial Transition Count	21
Initial Rule Names	add_parallel_branch, add_series_stage, move_cell

Manifest Parameters

Key	Value
max_depth_mm	500
max_height_mm	250
max_width_mm	500
minimum_capacity_ah	10
minimum_current_a	60
target_voltage_v	14.8
voltage_tolerance_v	0.1

Initial Transition Summary

Rule Name	Transition Count
add_parallel_branch	7
add_series_stage	7
move_cell	7

Library Interface

• initial_state()

• enumerate_transitions(state)

• enumerate_next_states(state)

• evaluate(state)