Last winter a storm knocked out our power for almost two days. My phone died on the first evening, and I spent the rest of the outage feeling completely cut off. No flashlight app, no weather updates, no way to text anyone. I promised myself that would never happen again, and it has not.

Here is the plan I built after that blackout. It costs less than you think and it all fits in one drawer.

Keep a charged power bank

The single best move is a power bank you keep topped up. A 10,000 mAh bank charges a typical phone two to three times, which covers a multi day outage. The trick is remembering to charge it before the storm, not during it. I plug mine in on the first day of every month, along with my other emergency gear, so it is always ready.

Use your car as a backup

If the power is out longer than your bank lasts, your car is a giant battery. Most cars have a USB port, and idling for ten minutes charges a phone several times over. If you are worried about fuel, ten minutes of idle uses a negligible amount, and newer cars charge the USB ports even without the engine running in many models.

Do not run the car in a closed garage. Pull it out or open the door wide for air.

Stretch the charge you have

When every percent counts, flip your phone into low power mode immediately. Then make these changes:

• Turn off Wi-Fi and Bluetooth. They constantly hunt for dead networks and burn battery doing it.
• Lower the screen brightness and shorten the screen timeout to thirty seconds.
• Close the apps you are not using, especially anything streaming or navigating.
• Use airplane mode if you do not need calls, then turn it off for a minute when you want to check messages. A phone searching for a weak cell tower drains fast.

What not to do

Do not charge your phone from your laptop and then wonder why the laptop died. Do not leave devices on chargers that have no power, they drain slowly backward on some models. And do not wait until the outage to find your power bank, because it will be in the drawer behind the thing you never use.

The next blackout hit us this spring. My phone stayed at 60 percent or above the whole time, and I was the neighbor with the flashlight app.