[Oeva-list] charging efficiency

Jeff Kim jeff.shorepower at gmail.com
Tue May 17 22:14:58 PDT 2011


Shecked the Salem PGE station.  It's working, so you should be good to go!

Jeff

On Tue, May 17, 2011 at 2:29 PM, Alan Batie <alan at batie.org> wrote:

> I think I need to adopt a tag line of "Having Range Anxiety so you don't
> have to" ;-)
>
> As I'm looking over the data from the trip this weekend (and there's a
> lot more to think about than I imagined! so full report coming later),
> I'm wondering about how to think about some of it:
>
> My car reported that it used 19kwh to go to Portland Saturday, 23kwh -
> 4kwh in regeneration.  I charged for 3 hrs total at the 3.3kwh stations
> along the way, and put in 15kwh at the fast charger, which adds up to
> about 25kwh, which seems consistent, since I know there is "overhead" in
> charging.
>
> When I got home, I pushed it by going directly from Salem to home ---
> I'd charged enough to make it to LBCC, but when I got to Albany, I
> realized that at the rate I was going, I could just make it, and did
> (albeit by driving 5mph below the speed limit from Albany to a couple
> miles from home): it said "10 miles" left, with the 2 red bars
> (
> http://alan.batie.org/photos/canon-a1000/2011/0515-leaf-pdx/img_2595-640.shtml
> ),
> and the Blink reported that that charge used 20.5kwh.  That is
> consistent with the 24kwh spec on the battery pack --- the 12 bars make
> it 2kwh/bar, so the 10 white bars add up to 20kwh.  But 20kwh of battery
> should mean 27kwh consumed at 75%...
>
> The Salem Nissan is almost exactly at the halfway point, and I left
> there about 2/3rds full showing "47 miles"
> (
> http://alan.batie.org/photos/canon-a1000/2011/0515-leaf-pdx/img_2593-640.shtml
> ).
>  The "10 miles" left is consistent with what I've found to be a useful
> ball park of 5 freeway miles/bar (it's better than that a little, but it
> makes a good rule of thumb).
>
> Going the other direction, if I assume that the charging efficiency is
> about 75% (19/25), that makes it 16kwh, which means it's more like 32kwh
> to get to Portland, and *that's* more consistent with what I'm seeing
> for the range on the car.
>
> One problem is that the bars are too coarse --- the 6 white bars I had
> when I left Salem could be "just barely past 5" so it could have been
> essentially 60% charge, which is consistent with what the car's
> reporting that indicates I could almost make it to Portland without
> recharging.
>
> I'm thinking about testing that this weekend: after stopping to check
> the PGE station and a 1hr charge there, and doing the whole trip at
> 60mph, see if I can make it all the way.  If I can, I might even be able
> to bring it up to an OEVA meeting ;-)
>
> Which is bringing up another consideration I didn't think I'd remotely
> have with an EV: the mileage on a lease.  At 15,000/yr, that's way more
> than I thought it capable of, but I have 900 miles on it now, after a
> month ;-)  That's 11K/year --- safe, but a lot closer than I expected!
>
>
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