On 16 Oct 2019 at 13:05, Lee Hart via EV wrote: > Consider hybrid cars; they generally get better fuel economy.
I'm not an engineer, so I'm treading hazardous waters here, but I'm not so sure I agree. As for pseudo-hybrid vehicles (fuel only, not true plug hybrids), as I understand it, there are several reasons for their improved efficiency. Not the least of these is that they almost never idle, and can shut down the engine when coasting in many cases. They also can use higher-efficienciency Atkinson cycle engines with inferior acceleration qualities, because they use the motor as an electric supercharger. And they recover some energy when braking, to use on the next acceleration. Now, about external genset and efficiency. An anecdotal counter-example worth citing is Alan Cocconi's 1993 Honda Civic hatchback conversion and his gasoline powered range extender trailer. Cocconi is no engineering slouch, so it's a good bet he built a fairly efficient genset. The combination got around 32mpg on the highway, if memory serves. That sounds pretty good, but the similar Civic VX hatchback of the same era returned 48-52 highway mpg. In this case, whether a Diesel bus would be more efficient burning the fuel directly vs an e-bus burning it in a charging genset depends on many factors, most of which we can't know without extensive research, and maybe not even then. This was in India, and I don't know how well optimized a typical Indian Diesel bus is for efficiency. We can probably assume that the genset wasn't optimized at all. It's a pretty good bet that the genset had a low grade, low efficiency alternator, and a simple, non-optimized Diesel engine. Also, there are inevitable conversion losses in the e-bus's charger. I would guess that for once the writer got it right, and it would have been better to have burned the Diesel fuel directly in a Diesel bus. Since most gensets tend to be lightly regulated, the genset's emissions were probably significantly higher than a bus's would have been, too. But it's only a guess, and I really have no way to determine which view is correct. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub ARCHIVE: http://www.evdl.org/archive/index.html INFO: http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
