I have a better idea.
Why not save power and use a larger storage than 20gb.
Here is a CF to iPod2g IDE adapter.
https://www.amazon.in/Generic-Compact-Flash-Adapter-Converter/dp/B00ZZ3AKGQ#customerReviews
The reviewer said it worked in their 2g iPod.
A 64gb CompactFlash is around $45
https://www.amazon.com/Sandisk-Extreme-CompactFlash-Memory-Card/dp/B00H3HEUYK/ref=sr_1_3?s=pc&ie=UTF8&qid=1513556044&sr=1-3&keywords=compact+flash