> > >So, if I have a 120 volt battery pack of T-105s, I multiple 120x124 and get >15,500 watts, or 15.5kW (VxA=W) of power on a fully charged battery pack. > Sort of. The pack voltage will sag under that kind of current, drop continuously -though slowly- until it gets down to 105V at which point the pack is empty (by definition a 120V pack is empty when it reaches 105V). For simplicity figure 110V average voltage, so you now have 13.64 kwh.
> >Now comes the mystery formula. According to the website, a Geo Metro using a >DC motor will use about 200 Watt hours per mile at 60mph. This number >supposedly came from a series of tests. Can anyone confirm/challenge? > Sounds like a fairly efficient vehicle, but yes that is a reasonable number over mostly flat ground, with little or no wind, and driving continuously without stopping. > >Anyway, if I divide 15,500 watts by 200 watts/mile, I get a range of 77.5 >miles at 60 mph -- I assume this means the batteries are completly drained at >the end. I know that isn't a good idea, so I'll by .80, to allow .20 left in >the batteries, and get 62.24 miles on a full charge at 60mph, which seems to >be in the ballpark for EVs. > >So, does this math look right? > Yup, except for the bit about voltage sag which you didn't know yet. This brings the 80% range down to about 55 miles. > >Now for the final question for tonight -- does all this mean that the vehicle >will be using energy at the rate of 200 watts per mile at 60mph? Is that an >appropriate way to look at the "fuel consumption"? In other words, once the >car reaches 60mph, it theoretically takes 200 watts per hour to keep it >going, assuming a flat road and no other external variables entering the >picture. Is that right? > Oops, 200 watts per mile is NOT the same as 200 watts per hour. You are going 60 mph, not 1 mph... 60 * 200 = 12,000 watts per hour.
