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,

-----Original Message-----
From: EV [] 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 <> wrote:

> http://electric-vehicle-discussion-list.413529.n4.
> tml
> 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 ...
> http://electric-vehicle-discussion-list.413529.n4.
> l
> 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 ...
> http://electric-vehicle-discussion-list.413529.n4.
> negligible-impact-on-EV-pack-capacity-td4687005.html
> EVLN: Researchers found delayed ToU G2V had a negligible impact on EV 
> pack capacity New study finds V2G discharging harmful to EV batteries
> +
> http://electric-vehicle-discussion-list.413529.n4.
> Charging-Stations-td4687004.html
> 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-
> posts-for-20170607-tp4687008.html
> Sent from the Electric Vehicle Discussion List mailing list archive at 
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Michael E. Ross
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