rx7locost wrote:
I have thought about an electric vehicle for my next project, But only casually. Let me do some BOE calculations on this:
Quote:
the Nissan leaf uses between 280-350 watts per mile, with the average person pulling 302watts per mile. I am not sure how that converts over to generator output numbers as they do not specify that but they talk alot about DC charging at Battery voltage with 8-10Kwh generators.. One of the common generators tossed around on the forums that people seem to favor is this little guy
Well, from what I can read, the generator you mentioned is a ~3KW generator (28.2Volt/105 Amp) It is powered by a ~3.5 KW gas engine. If the Leaf uses 300W per mile, then 1 hour of charging with this generator will get you enough electricity to get you 10 miles down the road. If you hope to use this for long distance driving, that would mean if you do not want to discharge the batteries, you could travel as fast as 10 MPH continuously until you run out of gas.
The gas generator consumes as much as 400g/KWHr. So at 3.5 KW (Engine output) 1 hr of running at full load would consume 1400g of gasoline per hour. At .75Kg/ Liter, that would be ~2.6 Kg or 5.72 lbs. At 6 lbs per USG, that would be ~.95 gallons yielding ~10.5 miles per gallon on gasoline.
Now maybe there is something wrong with my math, But the generator/trailer doesn't make any sense to me. It adds weight, lowering the range of the vehicle on battery alone, Doesn't provide enough power to run the vehicle by itself. The only possibility for it,, is if you have enough battery to get you from point A to point B. Once at point B, you would have a way to recharge the battery overnight, before you have to get back to point A.
BTW, don't forget to add the driver's weight when calculating the range on the batteries. Driver's weight in a 600 lb vehicle will make a significant difference in range.
Keep up the research. It would be fun to follow your build log.
I am not doubting your math and what not, but i am not understanding it... there are plenty of people on the EV forums claiming that these trailered setups give them sustained highway driving.. when loads are very minimal...then there is prime example car that i am looking at BMW i3 and then looking at your statements and not understanding it all.. please explain it more to me plz so i can understand it..
BMW i3 2,799lbs without REX, 3,064lbs with REX
Rex Specs:
7.4 kW continuous (25 kW MAX)
647 cc, two-cylinder generator
7.2 L (1.9 US gal) in the U.S
How does 7.4 kW continuous output able to power a 3,064lb SUV up to 70-80ish mph on the highway, but a smaller 10kw generator setup is unable to power a ultralight bike around 700lbs?