How to Choose a Button Cell: 4 Stages — Model and Size, Chemistry and Voltage, Operating Conditions and Life, Storage and Safety

Start with the model and size (how to read the code, and the different names for the same size); then the chemistry and voltage (lithium, alkaline, silver oxide, zinc-air); then the operating conditions and life (load, pulses, temperature, the conditions behind the rated capacity); and finally storage and safety (storage, no recharging, swallowing hazards). This article covers primary cells installed in equipment; rechargeable button cells and large storage batteries are out of scope. Four stages:

• Stage ① Model and size: reading the code; different names for the same size.
• Stage ② Chemistry and voltage: lithium, alkaline, silver oxide, zinc-air; voltage and discharge curves.
• Stage ③ Operating conditions and life: load, pulses, internal resistance, temperature, capacity conditions.
• Stage ④ Storage and safety: storage, no recharging, swallowing and safekeeping.

Source details are in the notes at the end. This is a general overview; each case needs its own assessment.

Stage ①: Model and size — read the code first

What to do:

• Start with the code on the equipment or the old cell. In the IEC naming system, the first letter is the chemistry, R means round, and the digits give the size: a CR2032 is a lithium cell 20 mm in diameter and 3.2 mm high.
• The same size can carry different names: makers call the same cell different things — for example, the cell with IEC name LR1154 is also sold as AG13, LR44, 357 or A76.
• The same model differs between makers and versions: capacity and operating temperature may be stated differently, so read the maker’s data sheet rather than relying on the code.

What public sources say: an online encyclopedia entry on button cells says they are small single cells, mostly 5 to 25 mm in diameter and 1 to 6 mm high; in IEC naming the first letter is the chemistry, R means round and the digits are the size, so a CR2032 is lithium, 20 mm across and 3.2 mm high; and makers use different names for the same cell, such as LR1154 also called AG13, LR44, 357 and A76. A battery maker’s lithium coin cell handbook (2018) gives the CR2032 a rated capacity of 240 mAh, discharged to 2 V. Another battery maker’s data sheet (undated) gives a CR2032 nominal capacity of 265 mAh under a 15 kΩ continuous load to a 2.0 V cutoff; the same maker’s other CR2032 data sheet gives 255 mAh under the same conditions.

Stage ②: Chemistry and voltage — the same size can have a different voltage

What to do:

• Start with the voltage the equipment needs: alkaline about 1.5 V, silver oxide about 1.55 V, zinc-air about 1.4 V, lithium about 3 V.
• Cells of the same size but different chemistry will fit, but life and voltage may differ. Lithium cells are not made in sizes interchangeable with 1.5 V cells; their much higher voltage than the equipment was designed for can cause permanent damage.
• Check how voltage falls: alkaline voltage is less stable; silver oxide holds a steady voltage until it drops suddenly near the end; lithium declines gradually. If the equipment needs a precise voltage, look at the discharge curve.
• Zinc-air: remove the seal before use; once it is off, the cell dries out within weeks even if unused.
• Mercury cells have been phased out because of toxicity; if older equipment specifies one, look up a current replacement separately.

What public sources say: the encyclopedia entry gives alkaline (L) about 1.5 V, silver oxide (S) about 1.55 V, zinc-air (P) about 1.4 V with high capacity, and lithium (C) about 3 V; it says cells of different chemistry in the same size fit mechanically but may differ in life and voltage, that lithium cells are not made interchangeable with 1.5 V cells and can permanently damage equipment, that alkaline cells usually have less capacity and less stable voltage, that silver oxide holds voltage until a sudden drop near the end and lithium declines gradually, that zinc-air cells dry out within weeks of removing the seal, and that mercury cells were phased out for toxicity. A battery maker’s alkaline button cell data sheet (undated) gives 1.5 V nominal and a typical 150 mAh at 7.5 kΩ continuous to 0.9 V, with voltage at 1.55 V at 0% depth of discharge, 1.33 V at 40% and 1.20 V at 80%. The same maker’s silver oxide data sheet (undated; the page marks it discontinued) gives 1.55 V nominal and a typical 150 mAh at 6.8 kΩ continuous to 1.2 V, designed for continuous low current.

How JIAHON can help: the page below does not sell button cells; it sells cylindrical and 9 V carbon-zinc and alkaline batteries, and is listed here because different chemistries mean different voltages and uses.

• Battery series: the specification overview lists three items: AA and AAA carbon-zinc batteries at 1.5 V, 14.4 mm diameter × 50.4 mm long (16.3 g) and 10.4 mm × 44.5 mm (8.9 g); and a 9 V alkaline battery, 26.5 × 17.5 × 48.5 mm (45 g). None of them is a button cell.

Stage ③: Operating conditions and life — under what conditions was capacity measured?

What to do:

• Check the conditions behind capacity: rated capacity is measured at a specific load and cutoff voltage; actual life depends on the equipment’s discharge current, operating temperature and cutoff voltage.
• If the equipment’s cutoff voltage is higher than the data sheet’s, part of the capacity can’t be used.
• For equipment with pulse loads (wireless transmission, motors), check how far voltage drops during pulses; it may hit cutoff sooner than average current suggests.
• Internal resistance: lithium coin cells have higher internal resistance than many other chemistries, and it usually rises during discharge; watch this for equipment with large pulses.
• Temperature: low temperature slows the reaction and reduces voltage and service time; check the data sheet’s operating range first, then where the equipment sits.

What public sources say: the lithium coin cell handbook (2018) says rated capacity assumes discharge to 2 V; usable capacity depends on discharge rate and cutoff voltage, efficiency is higher at low current, and an equipment cutoff above 2 V leaves capacity unused; for low-pulse uses capacity tracks average current, while high-pulse uses must allow for voltage drop during pulses, which can reach the 2 V cutoff sooner than average current suggests; lithium coin cells have higher internal resistance than many other chemistries — about 10 Ω for a new 2032 against about 0.3 Ω for an AAA alkaline cell — and it usually rises during discharge; low temperature slows internal reactions and ion movement, lowering voltage and service time; the recommended operating range is −30 to 60 °C. The other maker’s CR2032 data sheet (undated) gives −20 to +60 °C, 0.3 mA standard continuous current, 3 mA maximum continuous and 50 mA maximum pulse (1 second); its other CR2032 data sheet gives −30 to 70 °C.

How JIAHON can help: this stage is about capacity conditions, pulse capability, internal resistance and operating temperature. No product page states these; the battery series page mentions low-temperature tolerance in its summary but gives no range. Please ask, with the equipment’s discharge current, pulse load and operating temperature.

Stage ④: Storage and safety — manage cells in storage; swallowing is dangerous

What to do:

• Storage: normal room temperature and humidity; one data sheet gives 5 to 30 °C and humidity below 70% as an example.
• Long storage: lithium cells form a passivation layer that temporarily raises internal resistance, which usually eases with use under load; put the cell under load and observe before judging it.
• Not rechargeable: lithium coin cells are marked non-rechargeable. Don’t charge, short, crush, disassemble, heat above 100 °C, incinerate, or expose the contents to water.
• Equipment design: one data sheet recommends keeping holder contacts more than 3.2 mm from the negative edge.
• Safekeeping: a swallowed button cell burns the esophagus. Equipment within children’s reach should have a battery cover that needs a tool or two simultaneous actions to open; keep spare cells and cells for recycling out of children’s reach too.
• If swallowed: contact your local poison information service immediately; don’t wait for symptoms, and don’t delay going to the emergency room.
• Disposal: some button cells contain mercury or cadmium; follow local recycling rules.

What public sources say: the lithium coin cell handbook (2018) gives storage at normal room temperature and humidity, a 10-year shelf life and about 1% capacity loss per year; the lithium anode’s passivation layer slows self-discharge but may temporarily raise internal resistance after long storage, usually easing under load; swallowing a lithium coin cell is a serious hazard; and battery covers on equipment accessible to children should need a tool or two simultaneous actions to open. The other maker’s CR2032 data sheet (undated) recommends storage at 5 to 30 °C, gives self-discharge below 1% after a year at 20 °C, warns against charging, shorting, crushing, disassembly, heating above 100 °C, incineration or exposing contents to water, says to keep cells away from children, and recommends no contacts within 3.2 mm of the negative edge; its other data sheet gives storage humidity below 70%. The encyclopedia entry says a swallowed button cell reacts with saliva or mucus to produce alkali, burning the esophagus and other tissue; children under 5 are at higher risk, and cells 20 mm or larger cause severe injuries; putting a primary cell into a holder meant for rechargeable cells fits mechanically but is dangerous; and some button cells contain toxic mercury or cadmium. A US poison center’s page (undated) says to keep spare and used cells out of children’s sight and reach, choose products whose battery covers need a tool or have child locks, contact poison help immediately if a cell is swallowed without waiting for symptoms or delaying emergency care, and that 20 mm lithium coin cells are involved in most severe cases.

To match a cell, please prepare six items: the equipment’s code or the old cell; the voltage needed; discharge current and pulse load; operating temperature; storage and replacement arrangements; and whether the battery cover must be child-resistant. Please contact JIAHON or email [email protected].

RTC backup cells on PCBAs: soldering, assembly and storage

Button cells on electronic mainboards mostly keep the RTC (real-time clock) running during power loss. On an SMT/EMS line, first distinguish two ways of mounting:

• Holder plus cell. The holder is an ordinary SMT part, printed, placed and reflowed with the rest; the cell is fitted after reflow and cleaning. This is the common approach because the cell never sees reflow heat.
• Tabbed cell soldered directly to the board. Whether the tabs can go through reflow depends on the battery maker’s specification; if reflow is not stated as allowed, use hand or selective soldering, with time and temperature as the specification gives.

The most common line problem is cells discharged by short circuits: the terminals are close together, and on conductive ESD trays, conductive foam or metal fixtures a cell can slowly drain and only be found dead at shipment. So during receiving, staging and assembly, keep cells in the maker’s non-conductive packaging or dedicated dividers, not mixed with conductive packaging; if assembled boards are stacked, keep cells away from metal.

Related standards, named for reference only: IEC 60086-4 is the safety standard for primary lithium batteries; model codes and sizes follow the IEC 60086 series naming.

Notes: sources and limitations

Limitations:

• Figures (sizes, capacities, voltages, internal resistance, temperatures, currents, storage conditions, shelf life) are examples from the sources, not selection thresholds; Sources 3 to 6 are single-model data sheets, not general rules.
• Sources differ: CR2032 capacity is 240 mAh (Source 2, to 2 V), 265 mAh (Source 3) and 255 mAh (Source 4); operating temperature is −30 to 60, −20 to 60 and −30 to 70 °C. These are listed side by side; check the maker’s data sheet.
• Single-source points: zinc-air seal and drying (Source 1); silver oxide discontinued (Source 6); passivation and internal resistance figures (Source 2); 3.2 mm contact guidance (Source 3); humidity below 70% (Source 4); safekeeping of spare and used cells (Source 7).
• Source 7 is a US poison center; its US hotline is not given here — contact the poison information service where you are.
• Scope: primary cells in equipment; rechargeable button cells, large batteries, transport rules, model-by-model comparison, cost and lead time are excluded.
• Product figures were read from product page text on October 13, 2026, without images or data sheets, and were not independently verified; please ask about anything not stated.