Yes, you can take hearing aids in your carry-on luggage. They must not go in check-in luggage under any circumstances.
The hearing aid charger is a form of power bank.
Some types of batteries present a risk of them exploding and catching fire. Power banks present a significant risk, particularly when they are used to recharge other devices.
Some airlines, including Air New Zealand, specify in their conditions of carriage that you can only travel with your hearing aid chargers in carry-on and not check-in luggage. Please refer to their website https://www.airnewzealand.co.nz/travelling-with-lithium-batteries(external link).
For more information on the risks associated with power banks and other lithium batteries please read the Lithium Batteries - The Good, The Bad, and The Ugly [PDF 254 KB] article.
You will be asked to relinquish all dangerous or prohibited items found in your carry-on luggage. If you refuse:
AvSec x-ray bags going onto aircraft to ensure there is nothing dangerous in them. If something comes up on the x-ray that needs checking, the bag will be opened, searched and any dangerous good or prohibited item will be removed, with a bag search notification form left within the bag.