The Furibee F36’s stock 150mAh batteries are good for around 5 minutes of flying. But that’s without FPV gear. With FPV gear, that goes down to around 3 minutes. If you want to get back some of that flying time, you’ll have to put in bigger batteries.
There are three problems with bigger batteries. First, they will be a tight fit (or won’t at all) in the stock battery bay. Second, they will cover the battery connector. Third, they will offset the center of gravity. We need to address these problems before we can fly.