Yep, if you own a bundle of good 18650 torches that will tail stand and have a number of extra 18650 cells on hand you're in good shape come a power outage. Of course I also own a bunch of programmable ( Li-ion powered ) bike lights push-come-to-shove that will last days if I only use the lowest power levels. In a power outage the smaller EDC torches I can carry on me while the bigger 18650 torches I can set to low mode and let tail stand. One of these will easily provide enough light to light up a good size room. It also helps if you have a car charger so if needed you can still charge the batteries when needed. Of course in a power outage it also helps to have some tealight candles on hand. A bag of tealight candles are dirt cheap and one tea candle lasts a long time.

Three days without electricity!......super bummer! I can provide enough light to see what I'm doing for probably a week but without line-power you have no heat, no AC and no power to the fridge. No entertainment either unless you own a laptop, tablet or smartphone with built in wireless internet access. I have a smart phone but if I had to go days using just that I'd get tired of trying to view the small screen really fast. Lucky me, I've lived in a condo for 20 some years and have only had power outages a couple times and those only lasted a couple hours. That bag of tealight candles I have must be over 10 years old.