It all depends upon the load but my used battery (which was included with the purchase of the used LE1700) under my usage (around 20% CPU) and power saver, WiFi on constantly and quite low backlight brightness I get about 1.5 hours. In conjunction with a used extended battery I get about 2.5-3 hours.
I don't know how a new, fresh battery will perform.
Motion Computing LE1700 XGA VA, Samsung HS160JB 160GB HDD, 4GB Crucial RAM, Gigabyte GN-WS30N-RH 802.11n WiFi.
Motion Computing LS800 VA (undergoing updating and upgrading)