Make sure you're using a power supply that can provide a "2A" (2 amps) or more, otherwise your helmet will not charge, or charge up to 40% but not progress any further.
While you don't need to use the Forcite cable to charge your helmet, we do recommend it, as some other cable types have technical limitations. For example, cables that have the smaller USB-C connector at both ends use a method to set power delivery that can be set too low to charge the helmet, even if the charger and cable are capable of high current charging on a different device.
If you're using a 2 amp charger and the cable that came with your helmet, and your battery is still not charging past a specific percentage, it may have found a charging error and entered "safe mode".
To exit safe mode, follow these instructions: