----- Original Message ----- From: josh <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, August 30, 2002 2:07 PM Subject: Re: Got on the radio. Coast to coast AM. Subject:Hydrogen
> >Probably most EVs are getting 2-3 mi/kwh upstream of the charger > >(ie. on the AC side). > > Do you mean: as measured at the wall rather than by what's on board? It sounds > like you might mean something else. I mean what is coming out of the AC wall outlet, and that goes passing through my trusty portable AC kWh-meter that I can take down to the car in the carport and plug it into the line (or a Killa-Watt meter (that we had discussed awhile back on the list) - but these are not of much use because of their 15A limitation). > > >My Rabbit bounces around anywhere from > >1.5mi/kwh to 3.5mi/kwh, depending on how short my trip is (and > >how large a percentage of the trip is my big hill), how balanced > >the pack is, etc. I've measured this with an AC kwh-meter. > > I had thought your numbers were about what I've heard, but some of the folks > here seem to be claiming much higher. I test-drove a RAV4 EV the other day, and > I believe that the EPA mileage listed on the sticker worked out to very roughly > 3 mi/kWh. This is not to say that others here might not get much better, I'm > just mentioning. I don't know how they measure. Most numbers I've seen people mention are watt-hours/mi from their E-meter. The E-meter is measuring from a shunt, I believe it is between the battery pack (negative pole) and the controller, so the batteries, and their significant inefficiency, are out of the picture; these people are measuring the efficiency of their drivetrain and controller, as far as I can tell. I don't have an E-meter and wish that I did - someday... I also wish that when people cite a number like watt-hours/mi or whatever, that they clearly state where in the system that number comes from. It was only after a few years of being in the EV game that I realized where in the system most people were talking about - downstream of the battery pack. I suspect the RAV4 you mention above is most likely the energy that's coming through the AVCON charger port, but I certainly wouldn't bet my life on that. I guess I'd have to try and decide what the EPA sticker is really trying to say. On gas cars, the mpg gallon is the gallon that goes in the tank - I don't think there are significant losses till you get to the engine. > > >I've seen numbers of 33, 36, and 38 kWh in a gallon of gasoline. > > It's easy to convert kWh from BTU (3412 BTU per kWh) but it's hard to nail down > what's in a gallon of gasoline or Diesel. Neither is strictly defined, both can > vary. For gasoline I use 106,000 BTU, but it can be lower (even lower than > 100,000 I think) or higher (as high as 114,000 or maybe more I think), depending > I think in part on the season. For Diesel, I use about 140,000 BTU though this > also is not necessarily precise. I did some research into this once, and it was > just very hard to get a steady answer as to the energy content of a gallon of > gasoline. Hmm, I had more or less thought a gallon of gasoline (or diesel) had a pretty set quantity of energy contained within, but I could certainly have the wrong impression. The octane number is not supposed to affect the energy you get from your gasoline, assuming you are not dealing with detonation problems.
