The included rechargeable AA batteries are Ni-MH (Nickel-Metal Hydride) ones.

Unlike Li-ion batteries, it is normal for Ni-MH rechargeable batteries to heat up when charging. Do not worry about the slight temperature increase as there is a built-in temperature protection feature to prevent overheating.

The built-in temperature protection automatically stops charging when the battery temperature rises above the trigger point. When charging is stopped, remove the controllers from the charging dock and let them cool down for 5-10 minutes. You do not need to remove the batteries. After the controllers have cooled down, put them back onto the charging dock to resume charging.

If you're still concerned about the issue, please contact us for further assistance. Briefly mention the steps that you’ve already tried for a faster solution.