now, lets take a light plane for which I can find enough info to do this with, the jabiru j160D ok. so the fuel in it weighs (135L * 0.72kg/L) = 97.2kg. Now, the engine in it, the Jabiru 2200cc Aircraft Engine, weighs 62.8kg, and has a max power output of 60kw, and cruises at 75% power, so lets assume 50kw cruise power to account for takeoff and landing. So in total, engine and fuel weight 97.2 + 62.8 = 160kg
so lets rip that 160kg out and replace it with a EMRAX228 Brushless AC electric Motor with a 100kw power output and weighing in at 11.9kg, leaving us 148.1 kg worth of batteries, with a energy storage capacity of 148.1 * 0.66 = 97.746 kwh. so, at the cruise speed of 100knots = 185.2km/h, your looking at a range of (97.746kwh / 50kw) * 185.2km/h = 362km in about 2 hours.
The gasoline version can fly at the same speed for 8.5 hours. So, sure, the range is a quarter of the gasoline one, but you could ditch a passenger, chuck another 100kg of batteries in there and get that up to about 3.5 hours and 630km of range. Pretty damn good for a few dollars of electricity, negligible maintainence costs on a electric engine vs gasoline engine. sure as hell beats the $100+ youll pay for fuel alone for that same 3.5 hour trip.