Cell (Single) Symbol

The Cell (Single) symbol (IEC 60617 / ANSI Y32.2).

Definition: The Cell symbol represents a single electrochemical cell — the basic unit of DC supply — drawn per IEC 60617 as one long thin line (positive terminal, +) parallel to one short thick line (negative terminal, −) with a lead from each, the polarity being encoded entirely in the line lengths.

Also known as: cell, single cell, electrochemical cell, battery cell, voltaic cell, 1.5V cell, dry cell, primary cell.

What the Cell (Single) symbol means

The cell symbol denotes a single electrochemical source of electromotive force (EMF): one anode, one cathode and one electrolyte producing a fixed chemistry-dependent voltage. It is the atom of DC power in schematics — a 'battery' is, strictly, two or more cells connected together, and the battery symbol is literally drawn as a stack of cell symbols. The long line is always the positive terminal and the short, thicker line the negative terminal; a useful mnemonic is that the plus sign, having more strokes, matches the longer line.

In circuit analysis the cell is modelled as an ideal EMF in series with a small internal resistance r. Terminal voltage under load is EMF minus I×r, which is why a nearly flat cell still reads 1.5 V open-circuit but sags under load — a standard investigation in GCSE and A-level physics. Conventional current flows from the + terminal through the external circuit and back to the − terminal.

How to identify the Cell (Single) symbol

Look for exactly one pair of parallel lines: a long thin stroke and a short thick stroke, perpendicular to the connecting wires. That single pair is a cell. Two or more pairs stacked in a row (sometimes abbreviated with a dashed line between the end pairs) form the battery symbol. The + is at the long line even if the diagram omits the printed plus sign, so polarity can always be read from geometry alone.

IEC 60617 and ANSI Y32.2 / IEEE 315 draw the cell identically — this is one of the few symbols with no meaningful IEC/ANSI difference. The only variations you will encounter are optional printed + and − marks and, in power-electronics contexts, an enclosing box used for battery packs.

Function in a circuit

The cell drives current around a circuit by converting chemical energy to electrical energy, maintaining a potential difference across its terminals. Cells are combined in series to add voltage (two 1.5 V cells give 3 V — the classic torch battery arrangement) and in parallel to add capacity and current capability at the same voltage. Series cells must be oriented the same way; a reversed cell subtracts its EMF and, in rechargeable packs, risks damaging cell-reversal.

Because the internal resistance of a real cell rises as it discharges and as temperature drops, the cell symbol in an accurate model is accompanied by a small series resistor r. This determines the maximum current the cell can deliver (short-circuit current ≈ EMF/r) and the voltage sag seen by the load.

Standards: IEC vs ANSI

IEC 60617	IEC 60617 defines the primary/secondary cell symbol as one long thin line (positive) and one short thick line (negative). IEC 60086 standardises primary battery sizes and designations (e.g. LR6 = AA alkaline); IEC 61960 covers lithium-ion secondary cells.
ANSI/IEEE 315	ANSI Y32.2 / IEEE 315 uses the identical long-line/short-line cell symbol. North American size designations (AA, AAA, C, D, 9V) come from ANSI C18 standards, which parallel the IEC 60086 series.
Key difference	There is no practical drawing difference — IEC and ANSI cell symbols are the same. The only divergence is in battery nomenclature (IEC LR6 vs ANSI AA) and in whether + / − marks are printed alongside the lines, which both standards treat as optional since the line lengths already define polarity.

Terminals / pins

Pin	Name
pos	+
neg	-

Typical values

Nominal cell voltages by chemistry: zinc-carbon and alkaline 1.5 V; NiMH and NiCd 1.2 V; lead-acid 2.0–2.1 V per cell; lithium primary (CR coin cells) 3.0 V; lithium-ion/LiPo 3.6–3.7 V nominal (4.2 V fully charged); LiFePO4 3.2 V. Typical capacities: AA alkaline ≈ 2,000–3,000 mAh; AA NiMH ≈ 1,900–2,800 mAh; CR2032 ≈ 220 mAh. Internal resistance ranges from ~20–150 mΩ for a fresh AA alkaline to well under 50 mΩ for lithium-ion cells.

Where the Cell (Single) symbol is used

GCSE, KS3 and class 6–10 physics diagrams as the standard DC source for series/parallel circuit experiments
Torch (flashlight), toy and remote-control circuits running on one or more 1.5 V dry cells
Coin-cell (CR2032) backup supplies for real-time clocks, car key fobs and motherboard CMOS memory
Breadboard and Arduino hobby projects powered from AA holders or single lithium cells
Battery-pack design schematics where series cell strings set pack voltage (e.g. 3S LiPo = three 3.7 V cells)
Electrochemistry lessons illustrating voltaic/galvanic cells and electrode potentials

Example

In a single-cell LED test circuit, the Cell symbol's + pin (long line) feeds a 3 V lithium coin cell's positive terminal to a series 47 Ω resistor and then the LED anode, while the − pin (short thick line) returns from the LED cathode; reading the symbol's line lengths alone tells you which way the LED must face for current to flow.

Key facts

One long thin line plus one short thick line = one cell; the long line is always positive and the short line negative in both IEC and ANSI standards.
A battery is two or more cells — the battery symbol is drawn as multiple cell pairs stacked in series.
Nominal voltage depends on chemistry, not size: alkaline 1.5 V, NiMH 1.2 V, lead-acid 2 V, lithium-ion 3.6–3.7 V per cell.
A real cell is modelled as an ideal EMF in series with internal resistance r; terminal voltage under load = EMF − I×r.
Series connection adds voltages (cells must face the same way); parallel connection adds capacity at the same voltage.
Conventional current exits the + (long-line) terminal, flows through the external circuit, and re-enters at the − terminal.
The IEC/ANSI reference designator for a cell or battery is G (source) in IEC practice or BT in ANSI/IEEE practice.
An AA and a D alkaline cell are both 1.5 V — the larger cell stores more energy (capacity) but has the same EMF.

Diagrams that use this symbol

Photocell circuit diagram

Frequently asked questions

How do you draw the cell symbol for GCSE physics?

Draw two parallel lines perpendicular to the wire: one long and thin, one short and thick, with a small gap between them. Connect a wire to the middle of each line. The long line is the positive terminal and the short line is the negative terminal — examiners check this, so add + and − labels if you have any doubt. For a battery of cells, draw two or more of these pairs in a row.

What is the difference between the cell symbol and the battery symbol?

A cell symbol is a single long-line/short-line pair, representing one electrochemical cell (e.g. one 1.5 V AA). A battery symbol shows two or more pairs joined in series, because a battery is by definition a collection of cells — a 9 V PP3 'battery' really contains six 1.5 V cells. Many schematics loosely use one pair for any DC source, but the strict convention distinguishes them.

Which side of the cell symbol is positive?

The long, thin line is the positive terminal; the short, thick line is negative. This holds in both IEC 60617 and ANSI/IEEE 315 with no exceptions. A common mnemonic: the longer line matches the 'bigger' symbol (+), or think of the plus sign needing more ink. Printed + and − marks are optional because the geometry already defines polarity.

Why does a cell's voltage drop when current is drawn?

Every real cell has internal resistance r from its electrolyte and electrodes. When load current I flows, a voltage I×r is dropped inside the cell, so the terminal voltage falls to EMF − I×r. As the cell discharges, r rises, making the sag worse — which is why a 'dead' cell can still read near-nominal voltage on a multimeter (drawing microamps) yet fail to run a motor.

How do cells combine in series and parallel?

In series (+ of one to − of the next) the voltages add: three 1.5 V cells give 4.5 V at the capacity of one cell. In parallel (like terminals joined) the voltage stays at one cell's value but capacity and available current add. Series cells must all face the same direction — a reversed cell subtracts 1.5 V and gets charged backwards, which can leak or vent. Never parallel cells of different chemistries or states of charge.

Related symbols

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