39 Products
Your Current Vehicle
Or
Select Your Vehicle
A battery's size, chemistry and voltage are separate specifications
A cell converts stored chemical energy into direct-current electrical energy. Its case dimensions let it fit a holder, chemistry establishes voltage and discharge behaviour, and the device determines the current profile.
Two cells that occupy the same space can behave differently. Start with the device label or handbook, then match the complete battery designation.
Common domestic formats
| Format | Typical nominal voltage | Common chemistries | Selection caution |
|---|---|---|---|
| AAA / AA / C / D | 1.5 V primary; commonly 1.2 V rechargeable | Alkaline, primary lithium, NiMH | A lower rechargeable voltage may not suit every device. |
| 9 V rectangular | 9 V primary; rechargeable versions vary | Alkaline, lithium, NiMH | Exposed snap terminals short easily in storage. |
| Lithium coin cell | Often 3 V | Lithium manganese dioxide and other specified systems | Diameter alone does not identify thickness/capacity. |
| Silver-oxide button cell | About 1.55 V | Silver oxide | Use the exact size/code and drain characteristic. |
| Alkaline button cell | About 1.5 V | Alkaline | May not provide the stable discharge of a specified silver-oxide cell. |
| Special miniature cylinder | Varies by designation | Alkaline or lithium | Never infer voltage from shape. |
Primary and rechargeable cells
Primary means the electrochemistry is not designed for charging
Alkaline and most retail lithium coin cells are single-use. Applying charging current can cause leakage, pressure, rupture or fire. “Rechargeable-looking” size is not evidence.
Rechargeable cells need a chemistry-aware charger
A charger detects and controls voltage, current, temperature and termination for a defined chemistry and cell count. A NiMH charger is not a universal lithium charger. Follow both cell and charger instructions and never charge damaged cells.
How voltage changes through a battery's life
Nominal voltage is a convenient label, not a constant measurement. A fresh cell may read higher with no load; voltage falls under load due to internal resistance and changes as capacity is used. Some chemistries hold a flatter voltage and then decline sharply.
A simple open-circuit meter reading can therefore misclassify a weak cell. Test under the device's expected load or use an appropriate battery tester.
Capacity, current and runtime
Capacity is commonly expressed in ampere-hours or milliampere-hours under defined test conditions. It changes with discharge rate, temperature and end voltage. A high-drain light or motor can expose internal resistance that is irrelevant in a clock.
Do not compare a capacity number without confirming chemistry, load and test method. Runtime also depends on the device's efficiency and duty cycle.
Application and chemistry matching
| Device behaviour | Battery priority | Checks |
|---|---|---|
| Very low drain, long standby | Shelf life and leakage resistance. | Device chemistry approval and replacement interval. |
| High intermittent current | Low internal resistance. | Temperature, pulse demand and contact condition. |
| Frequent daily use | Rechargeable cycle life may be valuable. | Device accepts rechargeable voltage and charger is compatible. |
| Precision miniature electronics | Exact voltage curve and size. | Full coin/button designation, not diameter alone. |
| Safety alarm | Specified chemistry and dependable end-of-life indication. | Follow alarm maker's cell and test schedule. |
| Cold environment | Chemistry with suitable low-temperature performance. | Published operating limits for cell and device. |
Understanding battery codes
Consumer names such as AA or 9 V describe familiar formats. Coin and button cells use codes that may encode chemistry and dimensions, while manufacturers can also list cross-references. Similar-looking reference numbers are not automatically equivalent.
Confirm nominal voltage, diameter, height, terminal arrangement and device-approved chemistry. A thicker coin cell may damage a holder; a thinner one may lose contact.
Series and parallel arrangements
Cells in series add voltage while the same current passes through each. Cells in parallel can increase available capacity/current only in systems designed to share current safely. Never improvise either arrangement or mix cell states.
If a multi-cell device stops early, test every cell. One weak cell can be driven into reverse voltage by stronger neighbours and may leak.
Why mixing batteries is unsafe
Old and new cells, different chemistries, different capacities or unequal charge states reach exhaustion at different times. The stronger cells continue forcing current through the weak one, which can heat, vent or leak.
Replace the complete set and date the installation where the device has a maintenance schedule.
Installation checklist
| Step | What to do | Reason |
|---|---|---|
| Identify | Read device instructions and old cell's full code. | Prevents dimensional/voltage substitution. |
| Inspect | Check holder for corrosion, leakage and damaged springs. | Poor contacts create heat and false low-battery symptoms. |
| Clean safely | Follow device guidance; isolate power and use suitable PPE. | Leaked electrolyte may be corrosive. |
| Orient | Match positive and negative markings. | Reverse installation can damage cell/device. |
| Seat | Fit without bending contacts or forcing the cover. | Maintains pressure and enclosure integrity. |
| Secure | Close screw or child-resistant latch fully. | Prevents access and intermittent contact. |
| Test | Operate the device and its self-test where provided. | Confirms the complete system, not just the cells. |
Contact corrosion and leakage
White or coloured deposits, wetness and damaged plating indicate leakage or corrosion. Isolate the device and avoid skin/eye contact. The cleanup method depends on the leaked chemistry and device construction; generic neutralising advice can cause further damage.
Dispose of leaking cells in accordance with local collection guidance. If contacts are badly eaten or the circuit board is contaminated, professional repair may be uneconomic or unsafe.
Short-circuit prevention
Loose metal can connect positive and negative terminals and release energy as heat. Nine-volt terminals sit together on the top, while coin cells expose broad conductive faces. Keep cells packaged or in individual non-conductive holders.
Do not store them in a drawer with screws, tools, foil or jewellery. Insulate terminals for transport and recycling where the collection scheme requires it.
Coin-cell ingestion is a medical emergency
A swallowed button or coin cell can cause rapid internal injury even if the child initially appears well. Keep spare and used cells locked away, ensure battery compartments close with their original screw or secure latch, and check floors after replacement.
If ingestion or insertion into an ear or nose is suspected, seek emergency medical help immediately and follow professional advice. Do not wait for symptoms or induce vomiting.
Heat, fire and physical damage
Keep batteries away from flames, heaters, direct prolonged sun and water. Do not crush, puncture, dismantle or solder directly to retail cells unless they have manufacturer-provided tabs and a qualified assembly process.
A hot, swelling, hissing or smoking battery demands distance and an appropriate emergency response. Do not handle it bare-handed or seal a venting cell in an unsuitable container.
Storage and shelf life
Store in original packaging in a cool, dry place within stated temperature limits. Avoid refrigerators unless the manufacturer specifically recommends them; condensation can corrode terminals. Rotate stock by date and keep new cells separate from used ones.
Remove cells from equipment that will be unused for a long period when the device instructions advise it. Some safety equipment must remain continuously powered, so its maintenance rules take priority.
UK disposal and recycling
Portable batteries should be taken to an appropriate battery collection point rather than placed in household rubbish or fire. Many retailers and local recycling facilities provide collection. Protect terminals and separate damaged batteries according to the scheme's instructions.
Recycling recovers materials and keeps cells away from waste-handling equipment where they can short and start fires.
Practical domestic-battery FAQs
Q: Are all AA batteries interchangeable?
A: No. Size may match while chemistry, voltage, current capability and rechargeability differ; follow device guidance.
Q: Can I recharge an alkaline battery?
A: Not unless the specific cell is explicitly designed for a compatible charging system; ordinary primary alkaline cells must not be charged.
Q: Why is a rechargeable AA labelled 1.2 V?
A: NiMH chemistry has a different nominal voltage from a 1.5 V primary cell, and not every device accepts it.
Q: Can I mix old and new cells?
A: No. Unequal states can over-discharge, reverse or heat the weakest cell.
Q: Are coin cells with the same diameter equivalent?
A: No. Thickness, chemistry, voltage and capacity can differ.
Q: Why does a battery test well but fail in the device?
A: Open-circuit voltage may look normal while voltage collapses under load due to high internal resistance.
Q: How should 9-volt batteries be stored?
A: Keep terminals protected in packaging or a holder so metal cannot bridge them.
Q: What should I do with a leaking cell?
A: Isolate it, avoid contact, ventilate, follow chemistry/device cleanup guidance and use an appropriate recycling route.
Q: Should batteries be kept in a fridge?
A: Generally use a cool, dry room within published limits; refrigeration can create condensation unless specifically approved.
Q: Can I replace one cell in a multi-cell device?
A: Replace the complete set with matching fresh cells unless the device instructions state otherwise.
Q: What if a child may have swallowed a coin cell?
A: Seek emergency medical help immediately; do not wait for symptoms.
Q: May portable batteries go in household waste?
A: Use a suitable UK battery collection or recycling point instead.
Q: What determines battery runtime?
A: Chemistry, capacity, load profile, temperature, device efficiency and the voltage at which the device stops operating.
