On 2014-05-08, at 20:33, Michael Ross wrote: > I hear power density discussed...some chemistries have more or less of > this.... > Power has a time component so maybe power density has to do with how fast you > can get the work done with a battery? Probably a structural issue more so > than a chemistry issue?
That makes sense, since power is the rate at which energy is transformed, such as BTU/hr. But I'm a bit stymied by the "power density" of a battery. It makes sense in guesstimating how much acceleration you can get out of a vehicle, but I don't know what it would tell you about a battery. For example, Veggie Van Gogh (http://www.VeggieVanGogh.com) has a 105 horsepower engine and a gross weight of about five metric tonnes, a power density of about 16 kilowatts per megagram. That's not far from my diesel Vanagon, which has 49 HP and 2.4 metric tonnes, for 15.2 kW/Mg. And yet, the five-ton step van seems "peppier" than the Volkswagen, probably due to more low-end torque. After conversion to electric, the Vanagon will have half the power density, at 8.7 kW/Mg, from a TransWarP 9 with 28 horsepower and the same gross weight rating. But I'm hoping it will seem much peppier than that, because a series-wound motor can give full torque at low RPMs. :::: So long as humans were well fed and entertained adequately, they'd submit to increasingly draconian intrusions into their private lives. -- Thom Hartmann :::: Jan Steinman, EcoReality Co-op :::: _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
