When using 4G you will experience battery issues.Unfortunately battery technology hasn't kept pace with advancements in phones....Had to switch to extended battery for the Bionic before it became useable. Vendors should realize that just about all phones in 4G mode are useless with standard batteries and the extended make phones to bulky...They need to develop stronger batteries
Yes 4G will drain your battery faster than 3G, if you are getting a MIFI type of device you might want to invest in an extended battery like a 5000 mAh device, grant it will make your device seem a little overweight but the 9-12 hours you get with it, it's definately worth it. Hey 3Gstore has an incredible BlackFriday deal going on. I have supplied the link to the MIFI4510L extended battery they have others on the site, since you didnt mentioned which device you have I can assume it might be the 4510L.