C vs D battery
C and D batteries both produce 1.5 volts, but D cells are larger and hold roughly double the capacity of C cells. They are not interchangeable — the D cell is wider by approximately 7.7 mm.
Specifications
| Specification | C (LR14) | D (LR20) |
|---|---|---|
| IEC designation | LR14 | LR20 |
| Diameter | 26.2 mm | 34.2 mm |
| Height | 50.0 mm | 61.5 mm |
| Voltage (nominal) | 1.5 V | 1.5 V |
| Typical capacity (alkaline) | ~8,000 mAh | ~15,000 mAh |
| Typical capacity (NiMH) | ~5,000 mAh | ~10,000 mAh |
Are they interchangeable?
No. The D cell is 8 mm wider and 11.5 mm taller than a C cell — it will not fit in a C battery slot. A C-to-D adapter (C cell inside a D-sized sleeve) is possible since voltage matches, but runtime drops to about half since C capacity is ~53% of D capacity.
Typical devices
| C battery devices | D battery devices |
|---|---|
| Portable radios, medium flashlights, lanterns, some audio toys | Large flashlights, boom boxes, emergency radios, large lanterns, electric candles |
NiMH rechargeable options
Both C and D sizes are available in NiMH rechargeable formats. Rechargeable D cells typically offer around 10,000 mAh — lower than alkaline originals but rechargeable hundreds of times. For devices that see regular heavy use (flashlights, emergency radios), rechargeable NiMH is the cost-effective long-term choice.
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