[EVDL List]

Furthermore, at some point we'll need to address the people who don't have
dedicated parking. I suspect that many of these people will "fill up" at
commercial stations. The residential infrastructure may turn out to be a
relatively small problem.

Peri

-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On Behalf
Of Roger Stockton
Sent: 17 August, 2012 9:31 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] EVLN: GM Spark, the "we've got one too" electric
"compliance car"

[quote]Cor van de Water wrote:

> Suddenly we are back to a 15-18kW peak for the house and
> even that is hardly ever reached, otherwise a single pole pig
> could not service more than 1 or 2 houses and where I am
> staying, the single family houses are pretty big and still
> at least 8 houses share a single pole pig.

And here you have hit on exactly the problem that has the utilities worried.

The distribution transformers are apparently the weak link. Sure, there is
plenty of excess capacity at night to charge with, however, the utility has
sized the transformers based on the present loading and duty cycle. They
rely on the lighter loading at night to allow the transformers to cool down.

Even the present 3-6kW chargers have the utilities concerned; it seems
highly unlikely that 10-15kW chargers will be possible in residences in any
number until the distribution network is beefed up, regardless of whether
charging takes place during the day or at night.

FWIW, I suspect that 3-6kW charge capability will be all that is needed at
home regardless of the vehicle range capability. Statistics tell us that
most people don't drive 200-300mi per day; most are under 50mi. So, in the
event that someone does use most of their range, either they will replenish
the battery incrementally over multiple 8hr charge sessions (even at 3kW,
8hr can restore 100mi range at 240Wh/mi), or they will use a public/pay
ChaDeMo (or other) fast charger to replenish most of the charge quickly and
finish off at home.

Cheers,

Roger.


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