How to Fix a Disposable Vape That Won't Hit Delta 8 THC Austin How to Know When Your Disposable Vape Is Almost Empty? The Most Telling Signs The Hemp Doctor Disposable vape, just three components but what it bugs me how does it know when it's empty. Led flashes when no juice is left but how? What makes led flash? How to Know When Your Disposable Vape is Almost Empty Xmania.eu Vapes are harmful and can be highly addictive. Some disposable vapes have nearly tripled in nicotine strength in the span of only 5 years.