I have written several posts on my homemade battery packs and their many uses. You can learn how to make one at http://bit.ly/URpTwz. Recently I purchased some 12 volt LED light bulbs from C Crane http://www.ccrane.com/. With these and 15 feet of wire I was able to make a nice lighting setup that would light a room quite well.
I went to my local electric supply house and purchased some 20-gauge wire and MR16 light bases. The bulbs I got from C Crane fit into this type of socket. They are two prong. I soldered two of the light bases to the 20-gauge wire about 8 ft apart. A cigarette lighter was attached to the end of the wire. This plugs into the battery pack. When the lights are hung up, they light up a room quite adequately.
The 12-volt bulbs that I purchased produce 440 lumens of light and draw 4 watts. The battery box contains to 7 amp batteries. They should run the lights for 28 hours straight if you allowed the batteries to run all the way down. This is not recommended. I would recharge mine with the solar charger at every opportunity. More bulbs could be added if you need more light, it would just shorten your run time proportionally.
Do a search of this blog for battery packs and you will find more suggestions on how to use them.