48 volts does indeed seem low for a modern EV, particularly one that weighs more than 3,000 pounds and is expected to go more than 60 MPH. I had a 48vdc (nominal) Citicar (about 1350 pounds empty) a few years back. It would struggle to go over 35 MPH. With a 450 amp controller, there is about 29 HP available. For reference, a 1967 Beetle (about 1,800 pounds empty) had about twice the power available (53 hp), and they weren't exactly known for their acceleration or high speed prowess. Typical lithium cells have about a 3C discharge rate; 450 amps continuous would require 150Ah cells. Any discharge greater than 450 amps (in this 48v scenario) would need higher capacity cells, and physically larger cables and contactors. To increase power, it is easier and less expensive to increase voltage, rather than amperage. Based on the same physics, it would appear that any 48v system would only be useful as a parallel augmentation system in a hybrid vehicle, and not as a primary propulsion system in a vehicle intended for use on a modern freeway. My guess is that VW plans might include using a 48v battery linked to a higher voltage inverter driving a 120v or so AC motor. Even so, the stress on a 48v pack feeding this sort of system would be significant. Using a 48v pack might have a legal precedent, aimed at keeping some regulations or specific legislation at bay, as 48v is not considered high voltage.
Tom Keenan > On Feb 6, 2016, at 7:18 PM, Paul Wujek via EV <[email protected]> wrote: > > Does anyone have any thoughts on VW using 48-volt systems in planned EVs? > > Here's an article that claims that number > (http://www.autoblog.com/2016/02/05/volkswagen-golf-eighth-generation-information/#slide-endcap), > and I've seen others that repeat it. > > This seems a very low voltage for a modern EV. > > What kind of effects will this have on the design? > -- > *Paul Wujek* <[email protected]> about <http://goo.gl/3jnMdX> > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
