Your IQOS is charging slowly
Make sure you’re using the official IQOS cable and AC power adaptor. Charging your IQOS from a computer USB port, rather than from an official AC adaptor, can be up to 4 times less effective. Similarly, using a third-party cable can be up to 5 times less effective.
If your IQOS 3 DUO pocket charger is already fully charged when you connect it to a power supply, the last status light may blink. This is normal and does not indicate that your pocket charger is unable to charge. Conversely, if your IQOS 3 DUO pocket charger has been completely discharged, then it may need to be plugged in with an official AC adaptor for up to 20 minutes before any status light patterns appear.