If that’s not enough battery, iFixit’s slightly hackier mod can give you an ROG Ally X -beating 88Wh. Jsaux seems to be out of stock, but you can smash a “notify me” button.

TL;DR Key Takeaways : The JSAUX battery upgrade kit boosts the Asus ROG Ally’s battery capacity from 40Wh to 65Wh, offering significantly extended runtime for gaming and multitasking. Users can ...

This is what I used when upgrading my Ally, so my tips are based on using this kit. 👉See at: JSAUX.com The original ROG Ally has a 40Whr battery while the ROG Ally X has an 80Whr battery.