How to charge a Canon DSLR camera without charger?

I want to photograph star trails, aka, starstreaks. So I have to leave my camera (Canon DSLR EOS Rebel T3) on overnight. How can I make the battery last that long without buying any extra supplies? The battery is half full. Will my camera charge by plugging it into a USB converter cable, and then plugging it into... show more I want to photograph star trails, aka, starstreaks. So I have to leave my camera (Canon DSLR EOS Rebel T3) on overnight. How can I make the battery last that long without buying any extra supplies? The battery is half full. Will my camera charge by plugging it into a USB converter cable, and then plugging it into an outlet, using a outlet/usb plug? Please help!
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