18650 open-ended battery-pack graph grammar

An explicit-circuit grammar for adding 18650 cells one at a time, wiring arbitrary valid interconnects, and evaluating the resulting pack with a shared circuit backend.

See Grammar Problem Catalog for the grammar family index.

Quick Facts

Field	Value
Problem ID	`battery_pack_18650_open_ended`
Problem Family	grammar
Implementation	`design_research_problems.problems.grammar._battery_pack_open:BatteryPack18650OpenEndedProblem`
Capabilities	`discrete-actions`, `external-adapter`, `optional-evaluator`, `serializable-state`, `statement-markdown`
Study Suitability	none
Tags	`grammar`, `battery`, `graph-netlist`, `layout`, `co-design`

Taxonomy

Formulation: discrete_grammar
Convexity: not_applicable
Design Variable Type: discrete
Is Dynamic: no
Orientation: engineering_practical
Feasibility Ratio Hint: 0.05
Objective Mode: multi
Constraint Nature: hard
Bounds Summary: explicit 3D cell coordinates inside a fixed envelope plus an explicit battery-circuit netlist capped at 16 cells
Tags: grammar, battery, graph-netlist, layout, co-design

Statement

Design a battery pack using 18650 cells under an explicit electrical graph model. The grammar starts with a single cell and lets designers add one cell at a time already tied into the circuit, remove cells, move cells in space, add or remove interconnects between cell terminals, and choose the positive and negative pack terminals directly.

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. The evaluation path applies deterministic geometry and graph-validity checks first, then uses a shared library-owned equivalent-circuit simulation informed by a single-cell pybamm integration.

Problem Shape

Field	Value
State Type	BatteryCircuitState
Initial Transition Count	31
Initial Rule Names	`add_cell`, `add_connection`, `move_cell`, `set_pack_terminals`

Manifest Parameters

Key	Value
max_cell_count	16
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_cell	21
add_connection	1
move_cell	7
set_pack_terminals	2

Library Interface

initial_state()
enumerate_transitions(state)
enumerate_next_states(state)
evaluate(state)