Motorola DROID RAZR MAXX! Yeah, we are being facetious with that suggestion, but the truth is that the 3300mAh battery on the device will last you for some time with some judicious use.
Seriously, try to keep the phone in the charger until the lights go off. Any thing that can eat the batteries should be done only once the phone is fully charged and is plugged in. Once the lights go off, you need to conserve battery life. That means all of those YouTube videos you like to watch must wait. Do you visit Crackle to watch old Newsradio episodes? Congratulations. You have good taste. But again, you need to look ahead and assume that the power will be off for a few days so you must use restraint to keep the phone turned off until you need to make a call. Want to take pictures of the storm and put it on Instagram?
buy a car charger if you don't have one. This way, in case of a dire emergency, you can always use the car charger to juice up your phone enough to make a quick call. Considering how long it takes to fully recharge a battery using your car battery, you might end up burning some desperately needed fuel. Some gas stations that use electric power to run their pumps could be out of commission for some time. While you should by all means get a car charger, don't expect to completely top off your phone's battery with it.
If a storm is bad enough to knock out your carrier's network, a portable generator and microwave relay equipment might be deployed by your mobile operator. We were told last year that Verizon's cell towers contain a back-up genrator or an 8 hour battery which means that Big Red customers might be able to get service even if an entire area has no power.
With Issac expected to hit South Florida Sunday night, those in the path of the storm should be keeping their phone recharged right now. And if you have spare batteries, top them off as well. It might worth a quick trip to your local store to pick up a spare cell or two. And most of all, stay safe!