Can I use the same size wire to make a Y series harness, loop key and run to the charge port? or what is recommended. I will be using xt90s
Sure. But might as well make the charge wire a smaller gauge as it is sending less amperage. Fuse it though.
Is it safer to go bigger like 10 awg, and what’s the recommended awg size for the charging wires?
You can go to big sometimes. 12 is pretty much the standard unless you are etoxx and that dude is just off the hook.
If in doubt, use 12AWG power wires and 20AWG charge wires with a 10A fuse on the charge port.
Only use high-strand-count silicone-insulated wire, sometimes called “Superworm”.
No, don’t use 10AWG
Depends Aluminum has half the ampacity of Copper conductors. If you’re not certain you’re ordering 12 awg with copper conductors - get 10 awg.
12 awg multi-stranded silicone wire made with copper is perfectly sufficient. 12 awg aluminum will get HOT