When a device calls for serious, long-lasting power, it usually doesn’t ask for AA or AAA – it asks for D batteries. From heavy-duty flashlights and radios to soap dispensers and commercial equipment, D cells are the workhorses of the battery world.
In this guide, we’ll walk through what D batteries are, how they’re different, where they’re used, and how to choose the right type for your application – with plenty of practical tips for getting the most life from every cell.
What are D batteries?
D batteries (often called D cells or R20/LR20 cells) are large cylindrical dry-cell batteries used where devices need a lot of current for a long time.
Like AA and AAA, the letter “D” refers to size, not chemistry. Inside, you can have:
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Single-use alkaline or zinc-carbon cells
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High-performance lithium chemistries
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Rechargeable NiMH or NiCd cells
Because D batteries have more internal volume than smaller sizes, they can store more active material – which translates into higher capacity and longer runtime, especially in high-drain devices.
D battery size, voltage & capacity
A standard D battery is:
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Around 61.5 mm long
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Around 34.2 mm in diameter
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1.5 V nominal for most single-use chemistries (alkaline, zinc-carbon, many lithium D cells)
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Approx. 8,000–18,000 mAh capacity for typical zinc-carbon/alkaline variants
Compared with an AA cell (about 50.5 × 14.5 mm and up to ~3,000 mAh), a D battery can hold several times the energy.
That extra capacity is why D batteries show up in devices that:
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Draw higher current
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Run for long periods between changes
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Must stay reliable in emergency situations (torches, radios, safety equipment)
Types of D batteries: alkaline vs rechargeable
1. Primary (single-use) D batteries
Most everyday D cells are primary (non-rechargeable) alkaline or zinc-carbon batteries. They’re ideal when you need:
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Long shelf life
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Instant readiness in emergency kits
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No chargers or charging downtime
For most business and facility applications in Australia, alkaline D batteries are the go-to option because of their higher capacity and better performance under load compared with standard zinc-carbon cells.
“…for low-maintenance, single-use power, our range of primary D batteries is designed for reliable performance in everyday and commercial devices.”
2. Rechargeable D batteries (NiMH, NiCd & others)
Rechargeable NiMH D batteries usually provide around 1.2 V per cell and can be recharged hundreds of times, delivering strong long-term value where devices are used frequently.
They’re a smart choice when:
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Devices are used daily (e.g. radios, educational equipment, some medical devices – always check OEM specs)
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You want to reduce waste and total cost of ownership
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You’re happy to invest in chargers and manage charging cycles
“For reusable power, explore our NiMH rechargeable D batteries and chargers, ideal for frequently used equipment.”
What are D batteries used for?
Because of their size and capacity, D batteries are designed for high-drain or long-runtime devices, including:
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Heavy-duty torches and lanterns
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Radios and portable stereos
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Automatic soap, sanitiser and paper-towel dispensers
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Sensing and safety equipment (e.g. some alarms, monitoring devices)
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Certain commercial and industrial controls
“If you’re running lanterns, radios or dispensers across multiple sites, our bulk D batteries range makes it easy to standardise on reliable brands and cut per-unit costs.”
How to choose the right D battery for your device
When you’re standing in front of a shelf (or scrolling a product list), use these quick checks:
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Check the device label/manual
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Look for “D”, “LR20”, “R20” or specific chemistry recommendations.
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Match chemistry to usage
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Alkaline D batteries for most general-purpose and many high-drain devices
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Lithium D batteries (where specified) for extreme temperatures and critical gear
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Rechargeable NiMH D batteries for devices you use and recharge frequently
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Consider runtime vs budget
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Lower-cost zinc-carbon D cells suit very light, occasional loads
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Alkaline and lithium D cells deliver longer runtime and better performance under heavy load
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Think about purchasing pattern
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Facilities, schools and businesses usually save with bulk D batteries rather than individual blister packs – especially for standardised equipment fleets.
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How long do D batteries last?
There’s no single runtime number, because lifespan depends on:
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Battery chemistry and brand
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Device current draw (low- vs high-drain)
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Operating temperature
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How often the device is used
As a rough guide:
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A quality alkaline D battery in a low-drain device can last months to years between changes.
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In high-drain devices like powerful torches or radios, expect hours to days of active use per set, depending on mode and usage pattern.
For rechargeable D batteries, focus on cycle life – NiMH cells can typically be charged hundreds of times when used and stored correctly.
“Simple habits like avoiding deep discharge and storing batteries correctly can dramatically extend runtime – see our tips in How to Take Care of Your Device’s Battery.”
Storage, safety & recycling for D batteries
To keep D batteries safe and performing well, follow these essentials:
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Store in a cool, dry place, away from direct heat and moisture
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Keep batteries in their packaging or a container so terminals can’t short against metal objects
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Don’t mix old and new batteries in the same device
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Remove batteries from devices if you won’t use them for a long period
For end-of-life:
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In many regions, rechargeable batteries should be recycled, not sent to landfill
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Check your local council or recycling program for collection points
“For step-by-step advice on safe disposal and recycling options in Australia, read our article on Battery Disposal: The Right Way.”
Where to buy D batteries in bulk
Whether you’re stocking a maintenance cupboard, fitting out a school, or managing multiple commercial sites, having the right D batteries on hand prevents downtime and emergency call-outs.
At HBPlus Battery Specialists, you can:
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Choose from trusted brands like Procell, Duracell, Energizer and more
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Buy bulk D batteries by size, chemistry or brand
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Get expert support on matching batteries to your specific devices
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Browse our full range of bulk D batteries.
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If you’re standardising power across your organisation, explore our bulk batteries collection or talk to the team at HBPlus Battery Specialists about a tailored supply plan.”
