It would have helped if you had mentioned what camera you have.
Without that information, all I can say is check the User Manual and follow those instructions.
Alternatives:
1. You can buy NiMH batteries and charger that charge much faster than the one you have.
2. You can buy NiMH batteries that do not lose power just sitting in your camera.
...They are usually labeled "pre-charged".
3. You can buy an extra set of batteries and have them charging while you are using the other set.
Be battery aware - conserve battery power:
1. If your camera has GPS (global positioning system), turn it off when not using it.
...GPS can cut your battery time in half.
2. If your camera permits, turn the LCD off and use the viewfinder only.
3. If you download your pictures from the camera to your computer remember you are using battery power while doing that. A card reader uses no camera battery power.
..
I have another question here. My new camera came with 4 NI-MH rechargeable batteries.
These take over 13 hours to charge. I took only 20 pictures and they were discharged already. I know these cameras use a lot of power, but it seems they should last a little longer than that.
I was wondering if it is all right to use lithium batteries (such as I used in my old point-and-shoot camera) instead of the rechargeables? I wrote to the manufacturer about this but they never replied to my email. I don't want to risk damaging the camera and voiding the warranty. Thank you.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic