MagSafe charger not working for iPhone SE 2nd generation

Went to bed last night at 9:00, put my phone on the charger, got the “bong” sound and lightning bolt icon, so it appeared to be working. Woke up this morning at 6:00, and it was only on 15%. This has happened once before; I removed the Otterbox case before charging it last night because I thought this might be the problem, but no, it still didn’t charge. Anyone else experiencing this?