LiPo Battery Symbol
Definition: The LiPo Battery symbol represents a rechargeable lithium polymer electrochemical cell or pack delivering a nominal voltage of 3.7 V per cell (fully charged 4.2 V, minimum discharge 3.0 V), drawn in schematics as the standard battery symbol — one or more pairs of alternating long (positive) and short (negative) parallel lines — with a positive terminal pin (+) and a negative terminal pin (−), referenced in drawings as BT followed by a number.
Also known as: lithium polymer battery, LiPo cell, LiPoly battery, lithium-polymer accumulator, soft-pack battery, pouch cell battery.
What the LiPo Battery symbol means
The LiPo Battery symbol denotes a rechargeable energy storage element based on lithium-ion chemistry with a polymer gel or solid electrolyte, encased in a flexible aluminium-laminate pouch instead of a rigid metal can. In a schematic the symbol communicates that this node is a rechargeable DC power source with a specific voltage window (3.0–4.2 V per cell) and that the circuit must include charge management (a LiPo charger IC such as the TP4056) to avoid over-charging or over-discharging, which can permanently damage the cell or create a fire hazard.
LiPo batteries are the dominant energy source in portable electronics, wearables, UAVs (drones), and RC models because of their high energy density (150–260 Wh/kg), flat form factor, and ability to deliver high discharge currents (10–100 C for high-rate cells). The battery symbol in a wiring diagram marks the primary power supply node; the + pin feeds the system supply rail through a protection circuit module (PCM) or dedicated charge/discharge IC, while the − pin connects to the circuit's common ground.
How to identify the LiPo Battery symbol
The LiPo battery symbol follows the standard IEC/ANSI battery convention: one or more pairs of parallel horizontal lines where the longer line represents the positive terminal and the shorter line represents the negative terminal, all on a single vertical axis. A single-cell LiPo is drawn as one long/short pair; a 2S (7.4 V) pack is drawn as two such pairs in series. The positive terminal is labelled '+' and the negative terminal is labelled '−'. Some schematic tools add a 'LiPo' or '3.7V' text annotation beside the symbol. The pack capacity (in mAh) and C-rating may also be annotated.
Function in a circuit
A LiPo battery stores electrical energy by intercalating lithium ions between graphite anode and lithium cobalt oxide (or NMC/LFP) cathode layers through a polymer electrolyte during charging, and releases energy by reversing this process during discharge. The open-circuit voltage is approximately 3.7 V (nominal), 4.2 V at full charge, and 3.0 V at the safe minimum. A protection circuit module (PCM) or battery management system (BMS) is wired between the cell terminals and the circuit to interrupt current if voltage exceeds 4.25 V (overcharge) or drops below 2.75 V (over-discharge), or if discharge current exceeds the rated maximum.
Standards: IEC vs ANSI
| IEC 60617 | IEC 60617-02 defines the standard multi-cell battery symbol used for all electrochemical batteries including LiPo cells: alternating long (positive) and short (negative) parallel lines with + and − terminal labels. IEC 62133-2:2017 specifies safety requirements for portable sealed secondary lithium cells and batteries. UN 38.3 governs transport testing of lithium battery cells. |
|---|---|
| ANSI/IEEE 315 | ANSI Y32.2-1975 / IEEE 315-1975 defines the same alternating long/short line battery symbol for multi-cell batteries; single-cell batteries are drawn as one long and one short line. The standard does not distinguish LiPo from other lithium battery chemistries by symbol; chemistry is indicated by text annotation. |
| Key difference | The IEC and ANSI/IEEE battery symbols are visually identical: alternating long (positive) and short (negative) parallel lines. Neither standard defines a chemistry-specific glyph for LiPo versus Li-ion versus NiMH; the chemistry and rated voltage are always indicated by text annotation alongside the symbol. |
Terminals / pins
| Pin | Name |
|---|---|
| pos | + |
| neg | - |
Typical values
Nominal cell voltage: 3.7 V; Full charge voltage: 4.20 V (standard LiPo), 4.35 V (high-voltage LiPo, LiHV); Minimum discharge voltage: 3.0 V (recommended safe minimum); Energy density: 150–260 Wh/kg (gravimetric); Capacity range: 50 mAh (wearable cells) to 20,000 mAh (large packs); Continuous discharge rate: 1C–100C (depending on cell type); Cycle life: 300–500 cycles to 80% capacity (typical consumer LiPo); Self-discharge: ~2–5% per month at room temperature.
Where the LiPo Battery symbol is used
- Consumer portable electronics: smartphones, tablets, laptops, Bluetooth earbuds, and smartwatches all use LiPo pouch cells for their flat, lightweight energy storage
- UAVs (drones) and RC aircraft: high-rate LiPo packs (25C–100C) supply the high peak current demanded by brushless motors and ESCs during throttle bursts
- Wearable devices: ultra-thin LiPo cells (0.3–2 mm thick) power fitness trackers, hearing aids, medical patches, and smart clothing
- IoT and sensor nodes: small LiPo cells (100–1000 mAh) combined with a LiPo charger IC and LDO regulator form the power subsystem of wireless sensor nodes and beacon devices
- Power banks and portable chargers: multi-cell LiPo packs with integrated BMS and boost converter provide USB charging capability
- Electric bicycles, scooters, and light EVs: large-format LiPo packs or LFP (lithium iron phosphate) variants power the traction motor through an inverter
Example
In a portable GPS tracker schematic, a 3.7 V, 1000 mAh single-cell LiPo battery (BT1) connects its + pin through the protection circuit module (PCM) to the VBAT rail and its − pin to the ground plane. A TP4056 charger IC takes 5 V from a micro-USB connector and charges BT1 at 500 mA with programmable constant-current/constant-voltage charging; an MCP73831 LED driver on the TP4056's charge-status pin illuminates a red LED during charging and extinguishes it at full charge. The LiPo symbol in the schematic shows a single long/short line pair labelled 'BT1 / 3.7 V / 1000 mAh'.
Key facts
- A LiPo (lithium polymer) battery delivers a nominal cell voltage of 3.7 V, charges to 4.20 V (or 4.35 V for high-voltage LiHV cells), and must not be discharged below 3.0 V to prevent permanent capacity loss.
- The LiPo battery symbol follows the standard IEC 60617-02 / IEEE 315 battery convention: one or more pairs of alternating long-line (positive) and short-line (negative) parallel lines; chemistry is identified by text annotation, not by a specific glyph.
- A LiPo cell must always be used with a protection circuit module (PCM) or BMS that prevents overcharge (> 4.25 V), over-discharge (< 2.75 V), and overcurrent — conditions that can cause cell swelling, fire, or explosion.
- LiPo batteries have the highest gravimetric energy density (150–260 Wh/kg) of any commercially available rechargeable battery chemistry, making them the dominant choice for weight-critical portable applications.
- Multi-cell LiPo packs are rated in series-cell count: 1S = 3.7 V, 2S = 7.4 V, 3S = 11.1 V, 4S = 14.8 V (nominal); all series cells must be balanced during charging using a balance charger to prevent cell voltage divergence.
- The reference designator for a battery in schematics is BT followed by a number (e.g. BT1, BT2) in both IEC and IEEE 315 conventions.
- LiPo batteries are classified as Class 9 dangerous goods (UN 3480 for cells, UN 3481 for cells in equipment) under UN 38.3 transport regulations, requiring state-of-charge limits and packaging controls for air and sea shipping.
Frequently asked questions
What does the LiPo battery symbol look like in a schematic?
The LiPo battery symbol is identical to the standard battery symbol: one or more pairs of parallel horizontal lines where the longer line is the positive terminal (+) and the shorter line is the negative terminal (−), arranged on a vertical axis. A single-cell LiPo uses one long/short pair; a 2S pack uses two pairs in series. A text annotation (e.g. '3.7 V', 'LiPo', '1000 mAh') identifies the chemistry and capacity.
What voltage is a LiPo battery?
A single LiPo cell has a nominal voltage of 3.7 V, a fully charged voltage of 4.20 V, and a minimum safe discharge voltage of 3.0 V. Multi-cell packs multiply these voltages by the cell count: a 2S pack is nominally 7.4 V (fully charged 8.4 V); a 3S pack is 11.1 V (fully charged 12.6 V).
What is the difference between a LiPo and a Li-ion battery?
Lithium-ion (Li-ion) cells use a liquid electrolyte in a rigid cylindrical or prismatic metal can (e.g. 18650 cells). LiPo (lithium polymer) cells use a gel-polymer or solid electrolyte in a thin flexible aluminium-laminate pouch, allowing much thinner and lighter form factors. Both chemistries share the same 3.7 V nominal voltage and similar energy density; the primary difference is the electrolyte and packaging.
Does a LiPo battery need a protection circuit?
Yes. Every LiPo cell requires a protection circuit module (PCM) or battery management system (BMS) that monitors cell voltage and current. Without protection, overcharging (above 4.25 V) causes electrolyte breakdown and thermal runaway; over-discharging (below 2.75 V) causes irreversible copper dissolution that permanently degrades capacity. Overcurrent events cause resistive heating and can ignite the polymer electrolyte.
What standard defines the LiPo battery schematic symbol?
IEC 60617-02 defines the general battery symbol (alternating long and short parallel lines) used for all electrochemical battery types including LiPo cells. ANSI Y32.2-1975 / IEEE 315-1975 defines the identical symbol for North American schematics. Neither standard defines a chemistry-specific glyph for LiPo; the chemistry is indicated by text annotation alongside the symbol.
What is the reference designator for a LiPo battery in a schematic?
The reference designator for any battery, including LiPo, is BT followed by a sequential number: BT1, BT2, etc. This convention is defined by both IEC 60617 and IEEE 315-1975. Some engineers add a subscript or suffix (e.g. BT1_LIPO or BT1 3.7V) as an annotation to the designator to identify the chemistry.
What is a C-rating on a LiPo battery?
The C-rating on a LiPo battery specifies the maximum continuous discharge or charge current as a multiple of the pack's capacity in ampere-hours. A 1000 mAh pack rated at 20C can deliver 20 × 1 A = 20 A continuously. High-rate LiPo packs for drone and RC applications are rated at 25C–100C; standard consumer cells for portable electronics are rated 1C–3C. Exceeding the C-rating causes excessive heat, voltage sag, and accelerated cell degradation.
Place the LiPo Battery symbol on a wiring diagram or schematic in the free online circuit diagram maker — no download required.