EVDL Administrator via EV wrote:
On 14 Oct 2020 at 6:09, Jay Summet via EV wrote:
Regeneration is only about 20% efficient.
So they say - at least here on the EVDL. I've read similar declarations for
decades. But those statements aren't in accord with the data in the link I
provided.
http://evdl.org/pages/evergreen.html
"Range is not significantly affected by mountain driving. Essentially the
entire potential energy difference can be recovered by regenerative braking
and by coasting when possible. Nonetheless for optimal range, the
mountainous portion of a long journey should not be at or near the journey's
end."
I have a lot of respect for Axel Krause. So, with all due respect, I'd like
to see some documentation for that 20% figure, if you don't mind.
Indeed, regenerative braking only recovers about 20-30% of the energy
expended (battery-out to battery-in). This is due to the cascaded
efficiency losses of the battery, controller, motor, drive train, tires,
and aerodynamics on the way up; and then the same sequence of losses
again on the way down. Though each can be 90% efficient, they multiply
to nickel-and-dime you do death. If each is 90% efficient 0.9^12 = 28%.
But that's the worst-case. You're rarely going to drive up a mountain so
steep and long that you *double* your energy consumption going up, and
expend *zero* energy coasting back down. The more likely case is that
your horizontal drive is far longer than your vertical climb. So over
the length of your trip, you only expend a *little* more energy going up
than going sideways.
For example, you might spends 10 + 1 = 11 KWH going up; and then 10 -
25%(1) = 9.75 KWH coming back down. You only got back 25% of your
hill-climbing power; but the total trip used 11+9.75 = 20.75 KWH, which
is barely more than the 20 KWH that the trip would have taken on level
ground -- the loss of range is hardly noticeable.
Lee Hart
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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