There are generally two different areas of V2G (Vehicle to Grid) that each have
their own characteristics and are totally different in their impacts:
1. would better be called Grid Storage, this is where the grid is supplied with
less generation capacity than what is needed for longer periods of time so that
a storage buffer is needed to be filled during low consumption periods (nights
or morning) and is emptied during the afternoon/evening peak consumption
period, so it is a daily cycling application. This is often done in conjunction
with generation types that cannot be controlled such as wind and solar, they
might deliver enough energy to balance the daily need, but not always at every
point in time, hence the need for buffering. But the same thing can be designed
using traditional generation that has lower capacity than the afternoon/evening
peak needed, but which can deliver a total amount of energy throughout the day
to balance daily consumption
2. this would better be called brownout protection or stability control. There
are no large amounts of energy drawn from the battery ever, since the grid can
at any point in time generally deliver enough energy to cover consumption. But
there are short moments when consumption spikes or generation is switching or
starting up, where a short burst of power is needed to avoid the
voltage/frequency dropping below spec. Truly brown-out protection to bridge
over short periods (usually less than 1 second) of high power bursts.
The second case is very different from the first one.
The first one simply puts extra *full* cycles on the pack, wearing it out
The second one is virtually not measurable as added cycles, it behaves similar
to a vehicle driving around with regen braking: if you need to slow down a
little and then acclerate, so you put energy back into your battery for a
second and then accelerate again to pull that energy back out - those
micro-cycles are hardly noticeable, especially when done while the pack is near
Since V2G allows the *grid* to communicate to the charger to stretch out the
charging of the battery over the time until the car is needed again, it might
actually *prolong* the life of the pack, compared to simply charging full power
as soon as plugged in. So, the second case of V2G might be beneficial to the EV
not just in preserving his battery life, but also providing a more stable grid
and for being *paid* to make (part of) his battery capacity available for this.
Just my view,
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Michael Ross via EV
Sent: Wednesday, June 07, 2017 11:38 AM
To: brucedp5; Electric Vehicle Discussion List
Subject: Re: [EVDL] EVLN: EV-newswire posts for 20170607
Regarding the post: "EVLN: Researchers found delayed ToU G2V had a negligible
impact on EV pack capacity .
New study finds V2G discharging harmful to EV batteries " found in a paper
Durability and reliability of electric vehicle batteries under electric utility
grid operations: Bidirectional charging impact analysis ;" Journal of Power
Sources, Matthieu Dubarry
There is this comment which addresses my concern about the usefulness of the
"... Since battery degradation is path-dependent, any changes in usage can lead
to different degradation mechanisms and drastically influence the reliability
of the batteries.”
I am waiting for the full text to look closer at the charge and discharge
histories. I am not sure the path(s) they chose represent anything useful.
Too many possible configurations and charge/discharge histories to say if grid
connected EV packs necessarily must suffer this damage.
BTW, the article doesn't come up (needs subscription?). I used the info in
Bruce's transcription to find a source for the article. Hopefully it will be
shared without cost.
On Wed, Jun 7, 2017 at 4:42 AM, brucedp5 via EV <email@example.com> wrote:
> EVLN: Opel Ampera-e EV Is The Lastest Popemobile The current Pope
> Francis has been known to favor more low-key modes of transportation,
> but now he's received a more frugal kind of car altogether ...
> EVLN: Bolt EVs> A PIECE OF THE $2 BILLION PIE Barry Woods is all
> charged up about electric vehicles in Maine Woods is the only Mainer
> who has a full-time job promoting electric vehicles. As director of
> electric vehicle innovation for ReVision Energy of Portland, the
> state's ...
> EVLN: Researchers found delayed ToU G2V had a negligible impact on EV
> pack capacity New study finds V2G discharging harmful to EV batteries
> Mendocino_County-CA Adds New Electric-Vehicle Charging Stations ...
> ... upping the ante on its longstanding commitment to environmental
> sustainability by opening the second of a planned 14 electric-vehicle
> (EV) charging stations ...
> For all EVLN EV-newswire posts
> View this message in context: http://electric-vehicle-
> Sent from the Electric Vehicle Discussion List mailing list archive at
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To invent, you need a good imagination and a pile of junk.
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A public-opinion poll is no substitute for thought.
Michael E. Ross
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