How to make my electronics battery last longer?

I will be traveling all day on Tuesday. My Dell Laptop and iPhone 4S both have an okay battery life… A span of about seven hours, which isn't long enough for me. How can I make these batteries last longer? Also, is there such thing as an outlet on an airplane?

Well for iphone turn Wi-Fi and etc off, the usual as for laptop, good luck nothing usually lets it live longer that i'm aware of other than not using, also don't charge your phone threw the laptop, that drains its battery xD

Stick it in a fridge… The cold preserves battery life. However, I'm going to assume there's no fridge on the plane. You could buy another battery, but that will be a little expensive. For your Iphone you could buy a portable battery charger. I have one (Veho VCC-A008-PBP-XT Pebble Portable 5000mAH Battery Pack Charger for iPad/iPhone/iPod/Smartphones/PSP/NDS/NDS… And it is fantastic! Charges about 3 times and I got it off amazon.
Sometimes planes do have outlets on them! However, I wouldn't count on it. If you really want to know I would just call your airline and ask them.
If it comes to the worst you can always turn down the brightness on your screen a ton which will save your battery quite a bit!

Hope this helps!