Your Eco-drive will charge when exposed to any light source. The watch will charge fastest in natural sunlight. If you haven't worn your watch for a while and it has been stored in a dark place then simply place the watch on a dry window sill for 4-5 days.
For information on how to charge your Eco-Drive watch, you can visit https://www.citizenwatch.co.uk/setting-instructions. Depending on your model, the best practice charging method can vary. If you have any further questions on how to charge your watch, contact our service team at service@citizenwatch.co.uk or 0118 936 8855.