# item.guide
Side-by-Side Comparison Cylindrical Cells

18650 vs. D Battery

Comparing 2 standards across 4 specifications. 4 key differences identified.

Comparing:
18650
D Battery
18650 →

An 18650 Li-ion cell measures 18.6mm in diameter and 65.2mm in length. It operates at 3.6V/3.7V nominal, charges up to 4.2V max, and has a discharge cutoff of 2.5V with capacities between 2200 and 3500 mAh.

View full 18650 spec sheet →
D Battery →

A D battery (IEC designation LR20, ANSI 13A) measures 34.2mm in diameter and 61.5mm in length -- the largest common cylindrical primary cell. Alkaline D cells output 1.5V nominal, with typical capacity in the range of roughly 12,000 to 20,000 mAh depending on discharge rate.

View full D Battery spec sheet →

Specification Comparison Table

4 Parameters
Parameter / Spec
18650
D Battery
Diameter
18.60 mm 34.20 mm
Overall Length
65.20 mm 61.50 mm
Nominal Operating Voltage
3.60 / 3.70 V —
Alkaline Voltage
— 1.50 V

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