Larry, YMMV. The energy capacity, Amp Hrs, of a cell is very useful and you need to know the nominal cell voltage to go very far with it. Indeed you can get 200AmpHr at 3.2 V, no problem, as an example.
2 cells in parallel gets you the sum of amp hrs at the nominal voltage. 2 cells in series gets you the Amp Hrs of the least cell and the sum of the voltages. So you really don't want a lot of variety in a pack between the capacities of the cells or parallel cells that are in series. The series is only as good as the weakest link. A pack made with laptop cells is whole boatload of nominal cells in parallel to get the AmpHrs needed, and then those are duplicated in series to produce the voltage you desire. Once you have the voltage for the system, you can measure the amps and time to tell how much might be left to use or to be charged - at that particular pack voltage. KWhrs is more or less as you surmised KVAHrs. When you are talking about grid power you want to know the KWh because that is what you pay for, so the charging and making traction come together at KWhrs. AmpHours may be a good way to look at your "gas tank." And KWhrs your wallet. These are operating numbers. But there is a lot of $$ getting the AmpHrs as a capital expense (an up front expense) when you buy or build the EV whatever the voltage. I hope if I have made any errors or too gross oversimplifications that the corrections come quickly. On Wed, Jul 9, 2014 at 2:17 AM, Larry Gales via EV <ev@lists.evdl.org> wrote: > I know that watts = amps * volts, and watt-hours (wh) is a measure of > energy, but over and over again I hear people talking about EV batteries in > terms of amp-hours. What does that mean if you don't know the voltage? > 1000 amp-hr is not impressive if the voltage is, say, 0.00001 volts. Is > there some sort of standard voltage, e.g., 3.6 volts, that is assumed when > one talks about LiON batteries? Does amp-hours tell you something more > than watt-hours? > > Thanks in advance,-- > Larry Gales > > -- > Larry Gales > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140708/122acf6c/attachment.htm > > > _______________________________________________ > 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) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk michael.e.r...@gmail.com <michael.e.r...@gmail.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140709/db6537b5/attachment.htm> _______________________________________________ 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)
