Speaker wire question?

Hey all,

Would really appreciate your input on something as I am pretty new to this stuff and learning.

I'm doing this cooler speaker build, and have been kind of following a YT video to do so (have purchased the same products he used in the build etc.). He seems to know what he's talking about as he's done a lot of these type of builds.

The set up consists of two 5.25" 90 watt speakers, and one 8" 400 watt sub. These will be powered by a small 8.3ah 12V battery.

MY QUESTION: he uses 18 AWG wire for this system (including the sub). Will 18 gauge wire be good enough for the subwoofer? My initial thought was I would need 16 AWG, and was a little surprised to see he used 18 for everything. Does the 18 work for this set up (including the subwoofer) because 1. they are really short runs (1.5ft) and 2. has a really small power source?

Or should I ignore what he used, and get 16 AWG? I have a bunch of 18 laying around, so if it would work I would prefer to use it over buying a new spool.

Thank you in advance for you knowledge and wisdom. I really appreciate it!!