Hi. I ripped some CD-i Games from my actual discs, and using CHDMAN, I converted them all to CHD, from BIN/CUE, but all the CHD Files are super small, and don't seem to start in MESS. Am I doing something wrong?

Yes, you want to play a CD-i game, and that, my friend, is very wrong.

Try CD-i Fan´s tool called " cdifile " (Download section). Very easy to convert a CD-i disc image file to chd format. This tool support different CD file formats.

cdifile CDIFILE -createcd

example:
cdifile cd.cdi -createcd
cdifile cd.bin -createcd
cdifile cd.nrg -createcd
etc.

Unfortunately, newer versions of chdman are no longer supported by cdifile 0.5.1.
Try a older one of the chdman, example: version 0.135.1 (Nov 9 2009)

cdifile and chdman must be in the same folder.

Try the demo of " Frog Feast " (Copyright 2005-10 RasterSoft )
Here the right format for MESS.
If you have still problems, something must be wrong on your version, configuration or may the needed Bios is missing (MESS).
If the Frog Feast demo is working but not your image, something must be wrong on your created .CHD image.

Forgot to say, chdman and cdifile not support multisessions yet.

Using the older version of chdman made the images work. Thank you. Although the games freeze in-game, they do actually start now.

To avoid any misunderstanding, you can use the actual chdman but it can, depent of the available raw CD format, a bit more complex to create a image in .CHD format.
For .CDI, .IMG, .NRG images you need a CD burning tool (mode2_raw format with 2352 bytes/sector) to create BIN/CUE or DAT/TOC files.

Example for the DAT/TOC file:

chdman -createcd cd.toc cd.chd

Example for the BIN/CUE file:

chdman -createcd cd.cue cd.chd