WIth the range extender, if you don't mind using gasoline, you wouldn't need to recharge until you got home again. You'd also have to refill the tank. It depends on what type of recharging unit you might have...120vac (level 1 in the USA), level 2 (240vac), or a high voltage DC CCS unit (not something the average person would buy). A typical 120vac receptacle is only 15A, and the biggest EVSE you can safely use on it is 12A...with that, you would NOT be able to recharge the battery during a typical workday. Not all level 2 units are created equal...many commercial units are powered by 208 vac, so even if it's a max of say 32A (about the max the i3 can use), for 80-miles, it would probably take about 4-hours. If you have a 240vac unit with about 32A, 80-miles would probably take about 3+ hours. Now, if you have access to a CCS unit, they also are not all created equal...the max generally available is a 50Kw unit, some are as small as 24Kw. At 50Kw, you'd get nearly 80% from empty (you wouldn't be) in about 30-40 minutes.