Hi tmn0, not sure what you're asking, but I think it's around a USB 3G plug quickly draining power from your VivoTab? I've used a 3G dongle multiple times on the train, and havne't noticed a huge impact on battery drain. It takes a little more power than using WiFi, but overall only reduces about 1 hour of battery (from around 9hrs to 8hrs before a recharge is needed).
Maybe it's an issue with your USB stick (dongle)?
kd