What's Inside Size C and D Batteries?

A Complete Guide to C Batteries

Why do we use 3 AAA instead of 1 or 2 AA batteries? Is there a huge output difference? - Quora

Sub C Rechargeable Batteries from Canada.

Sleeves and spacers turn AA or AAA batteries into C- or D-cell

What's Inside Size C and D Batteries?

D Cell Batteries - USB Rechargeable Lithium D Batteries - 1.5V / 4000mAh (2-Pack) - Not NI-MH/NI-CD/Alkaline Batteries - ECO-Friendly & Recyclable - No Memory Effect

The Best D-Size Rechargeable Batteries - Reactual

AA battery - Wikipedia

Quick hack: The $1 C-to-D adapter

C Battery vs. D Battery: The Ultimate Guide