Sorry I didn't read your question correctly - You do NOT need 15W to charge the phone - you only need 15W to FAST charge the phone. I have 2 10W chargers that work just fine, they just don't fast charge. This is the most recent one I bought - it's a stand up charger - https://www.amazon.com/gp/product/B06ZYLQ2TP/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1