On 3/25/15 2:48 PM, Michael Ross wrote:
I won't challenge your ideas of Li ion cell life here, but there is new
information. We have gone around that recently on the list.
Why Li ion batteries die. by Dr. Jeff Dahn
https://www.youtube.com/watch?v=pxP0Cu00sZs
Dahn says that cells don't have to die, and I believe him.
Thanks again for the video link from Oct 31, 2013. In it Dahn said,
theoretically, if CE=1 (charge=discharge) the cell will last forever.
But more realistically he talked about efforts to improve cell life by
using additives to incrementally reduce coulombic inefficiency. His
measurement techniques allow quick experiments to find the most
effective combinations of additives. Clever approach.
I may have missed the part where he made a claim for actual infinite
battery life, but he did show evidence of how different chemical
additives measurably improve the life of the cells, by apparently
reducing parasitic reactions that can cause a premature drop in battery
performance due to plating.
That aligns with speculation about how Nissan may have progressively
adjusted their battery chemistry in their newer packs, in attempts to
mitigate premature degradation seen in earlier packs in hot climates.
Cheers,
-Jamie
Rickard (EVTV) thinks he proved that LFP cells have a shelf life
(deteriorate a little just sitting).. I am not sure his estimates are
definitive.
For the original work on high precision coulometry:
http://www.dal.ca/diff/dahn/publications.html
Aaron Smith is now the engineer responsible for cell life at Tesla.
Chris Burns is building and selling HPC test equipment.
http://www.novonix.ca/
Linden's Handbook of Batteries - Chapter 26.
*http://tinyurl.com/narq9nw*
*
*
Best regards,
MIke
*
*
On Wed, Mar 25, 2015 at 1:26 PM, Jamie K via EV <[email protected]
<mailto:[email protected]>> wrote:
On 3/25/15 10:11 AM, Michael Ross wrote:
Yes, the severe problem is in hot climates. So much of Europe
is not
going to see the issue. Though some may. Put a charged Leaf in a
garage on a rock in Greece or Spain, let it heat up good in the
summer
sun and you will see some deterioration like in AZ. Unless they
have
made some improvements.
Casual speculation aside, yes, they have made ongoing improvements
to the LEAF battery pack. It's worth reading this link:
http://www.mynissanleaf.com/____viewtopic.php?f=4&t=17168&____hilit=+battery+update#p374490
<http://www.mynissanleaf.com/__viewtopic.php?f=4&t=17168&__hilit=+battery+update#p374490>
Five year warranty on a pack is not really very good. If you get
to 5
years, do they honor it further out to 60K? No, or they would
just have
a 60K warranty. So it is 5 years or less if one drives 60K.
Here in the
US 60k miles might use up $6000 in fuel on a similar size ICE
car, less
if the car is efficient.
Here is Nissan's information on the battery warranty:
http://nissannews.com/en-US/__nissan/usa/releases/nissan-__announces-battery-replacement-__program-for-leaf
<http://nissannews.com/en-US/nissan/usa/releases/nissan-announces-battery-replacement-program-for-leaf>
It's hard to predict what a gas car's fuel cost will be over the
next five years in the USA, but it's a fair guess that the price
will remain volatile and trend upwards, on average. Electricity
prices are generally lower, less volatile and costs generally go up
more slowly. Some folks lock in a low electric cost by installing
solar panels. It also helps that electric cars are more efficient
than gas cars.
At ~60 miles to a charge, not much driving gets done, and a Leaf
yields
a poor payback against gas prices in the US if the battery pack
makes
trouble. If I had to buy a $5500 pack and some unknown labor
every 5
years that would really suck. I expect cars to last 10+ years.
According to my understanding of Li ion cells, it is possible to
select
cells, make packs and manage them for nearly unlimited life with
no loss
of capacity. You have to cool them, oversize them, undercharge
them, and
under discharge them. Not many EV manufacturers on that path
yet. Here
is hoping the new testing catches on and they all wise up.
AFAIK there are two ways that lithium batteries deteriorate:
By use (cycles) and by calendar life. Managing charge levels and
temperature helps optimize battery life within those limits. I
haven't heard of an infinite life lithium battery, but maybe that
will happen someday.
Meanwhile a roughly 24kWh battery at $6K or less for replacement
(today's cost) after 5-10 years (depending on how much range you
need) is about $250 per KWh, which is actually a market leading low
price. The price could come down further and/or the available
capacity of the pack could go up by the time a typical LEAF pack
would need to be replaced.
If ROI is your primary consideration when purchasing a car then you
would want to make a complete accounting, including all of the
maintenance and repair expenses over whatever you consider to be the
car's useful life. Plus fuel costs.
I would put battery replacement in the maintenance/repair category.
There isn't much else in that category for the LEAF since it
obviously doesn't require a gas car's typical
engine/transmission/fuel system/exhaust system parts-fest. With
regen, the LEAF doesn't even use the brake pads much.
The LEAF is widely available today, has a decent feature set, and an
improved battery from at least 2013 forward. Electric vehicles offer
important advantages, so I'm glad it's available along with other
choices. It's the current best-selling BEV for a variety of reasons.
Only you know what works for you.
Cheers,
-Jamie
SNIP
--
To invent, you need a good imagination and a pile of junk.
Thomas A. Edison
<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html>
A public-opinion poll is no substitute for thought.
*Warren Buffet*
Michael E. Ross
(919) 585-6737 Land
(919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone
(919) 631-1451 Cell
[email protected] <mailto:[email protected]>
<mailto:[email protected]>
_______________________________________________
UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
http://lists.evdl.org/listinfo.cgi/ev-evdl.org
For EV drag racing discussion, please use NEDRA
(http://groups.yahoo.com/group/NEDRA)
