tonymil
Posts: 274
Joined: Mon Apr 16, 2012 6:50 am
Location: Latham, NY

Re: Battery degradation

Tue Feb 17, 2015 7:44 pm

Really good news about battery degradation from Tesla:

According to Saxton’s data, the S60 version, whose smaller battery must undergo more charge/discharge cycles to travel the same distance, retains 90 percent capacity to about 67,000 miles.


Here is the entire article:

http://www.greencarreports.com/news/1096801_tesla-model-s-battery-life-how-much-range-loss-for-electric-car-over-time

JoeS
Site Moderator
Posts: 3937
Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: Battery degradation

Wed Feb 18, 2015 9:40 am

One notable difference between our i-MiEVs and a Tesla is the percentage of capacity that is used on a daily basis.

Despite its astounding range abilities, most Tesla owners I suspect only drive, on average, under 50 miles a day - anecdotally corroborated as whenever I ask a Tesla owner what distances they normally drive and what the longest trips they've made, the answers I get leave me shaking my head… Elon Musk is truly pandering to people's perceptions; nevertheless, I do envy their ability to drive just about anywhere without relying on a public charging infrastructure.

Back on-topic, our much higher SoC excursions in the i-MiEV means we stress our battery pack a lot more than a Tesla owner does. I suspect that in Tesla's case that aging rather than 'wear' may end up being the primary cause for their battery degradation, with aging in calendar years also being dependent on lots of variables. Pity we can't just flush it out and add potassium hydroxide like in Edison's ageless nickel-iron battery… oops, OT again.

I am hoping that in five years' time that there will either be third-party Lithium battery rebuilders (shipping costs could be a problem) or Mitsu will provide a low-cost battery upgrade path.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

jsantala
Posts: 296
Joined: Fri Sep 12, 2014 9:32 pm
Location: Finland
Contact: Website

Re: Battery degradation

Wed Feb 18, 2015 12:58 pm

If I had to bet, I would bet against any viable battery upgrades for any current EVs (excluding Tesla, which is a premium brand). Significant battery upgrades from Mitsu or Nissan will not happen. They will much rather sell you a new car. Selling better batteries is not in their interest at all. It would only keep old cars on the road and why on earth would a manufacturer want that.

3rd party upgrades might be possible, but I would consider them highly unlikely. I wish I'm wrong, but I just don't see it happening. Personally I'd be very interested in improved cells in the same form factor and with similar voltage characteristics to replace the Mitsu cells. They would make a very tempting upgrade path for a DYI person like me. I'm just not holding my breath.
kWsaki.com / EVs: Nissan Leaf 2012, Citroën Xsara 1997 (conv. 81V & 8" Series DC) and Kawasaki GPX750R 1987 (conv. 87V & ME1003 PMDC) / Used to have a Citroën C-Zero 2011

pbui19
Posts: 185
Joined: Tue Jan 07, 2014 12:17 pm

Re: Battery degradation

Sun Mar 22, 2015 7:42 am

hello - found this interesting study & publication on optimizing EV Battery:

http://www.academia.edu/6880205/Electri ... egradation

I apologize in advance if this has been posted previously. The paper is dated back in 2011, and the model was for a LiCo. My take away is fig. 10, where the best charging method for longevity is "Late L2 charging", i.e. ending charging close to usage time, to minimize high SOC duration.

Keep in mind that this is a model study. But I think I'll use that time delay feature on my EVSE.

Cheers,

Don
Site Moderator
Posts: 2997
Joined: Thu May 10, 2012 3:55 pm
Location: Biloxi MS

Re: Battery degradation

Sun Mar 22, 2015 11:55 am

I hope that one day we'll see eBay auctions for a few cells removed from battery packs which fit our cars - I'd buy a couple just to have in the event of a cell failure after the warranty period is over

Don
2012 iMiEV SE Premium, White
2012 iMiEV SE Premium, Raspberry Metallic
2012 iMiEV SE, White
2017 Chevy Volt Premier
2014 Ford Transit Connect XLT SWB wagon
2006 Itasca Navion Sprinter Motor Home

Vesilemb
Posts: 1
Joined: Thu Mar 26, 2015 5:34 am
Location: Estonia

Re: Battery degradation

Thu Mar 26, 2015 7:07 am

jray3 wrote:Thank you Kuuuurija
The photo of a snowbound i-MiEV on CHAdeMO makes me wonder is this capacity loss is due to the lithium plating issue in cold conditions. Any further data would be appreciated. I've always thought that one of Mitsubishi's very few technical errors was to not use the battery heating system for capacity and service life optimization, only for pack protection in extreme cold.

Hmmmmm....



I am frequent user of rental iMievs whitch are the same age of these 500 iMievs here in Estonia. I suspect that the main cause of dead battery is keeping these iMievs constantly plugged and charged to 100%, while rental iMievs are charged mostly by quickchargers to no more than 80%. Plating at cold temperatures isn't a problem, as charging current is limited when battery is cold. when battery heats up, it is able to accept currents up to 120A again. These rental iMivs have some 35000 to 40 000km.
These government iMievs see very little use. an average is about 500-1500km per year. Which is very low usage.

Phximiev
Posts: 1230
Joined: Thu Jan 15, 2015 7:25 pm
Location: Phoenix

Re: Battery degradation

Fri Mar 27, 2015 3:41 pm

I ran across this video from the Phoenix Electric Automotive Association Facebook page. I thought the video was quite interesting, hopefully this isn't a duplicate post.

Check out this video on YouTube:

http://youtu.be/pxP0Cu00sZs

And I wonder if the Mitsubishi batteries have been tested like this?
2012 iMIEV ES
2014 Chevy Volt

JoeS
Site Moderator
Posts: 3937
Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: Battery degradation

Fri Mar 27, 2015 6:54 pm

Phximiev, thank you for posting. Anyone have an executive summary?
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

Phximiev
Posts: 1230
Joined: Thu Jan 15, 2015 7:25 pm
Location: Phoenix

Re: Battery degradation

Fri Mar 27, 2015 8:34 pm

Try this for a summary. However, I watched the entire video and woud encourage all to do the same. Its quite thought provoking.

http://batteryuniversity.com/learn/arti ... ion_to_die

;-)
2012 iMIEV ES
2014 Chevy Volt

JoeS
Site Moderator
Posts: 3937
Joined: Thu Dec 15, 2011 5:47 am
Location: Silicon Valley, California

Re: Battery degradation

Sun Apr 05, 2015 3:07 pm

Found the following summary of the Jeff Dahn video that Phximiev identified -

http://powercartel.com/2014/11/notes-from-why-do-li-ion-batteries-die-lecture/

At Dalhousie University they have come up with techniques for predicting battery life based on very accurately measuring various parameters, especially utilizing precision microcalorimetry. In the video (which I finally watched but admit to falling asleep at some point) prof. Dahn addresses the problems facing manufacturers in trying to determine life expectancy and offers them help in that area - yes, I thought there was a little bit of a sales pitch in there; however, he does present a lot of useful information along the way, and it is also quite up-to-date.

Since I'm not in the business of building cells and batteries but am simply the end-user wanting to protect my investment, the message I got from all this is even more emphasis on NOT fully charging the pack in high temperatures and then letting it sit there, as high cell voltage + high temperature = bad news.

From a practical standpoint and for the time duration of interest to me I gathered that not much harm will come from fully fully charging just before taking off and then discharging the pack. Talking with Terry Kershner who has racked up more long-distance trips on his modified Zero electric motorcycle than just about anyone, I understood that he actually even slightly overcharges his pack (in order to squeak out the most available kWh), with the proviso that he takes off immediately after charging.

For anyone interested, there was more discussion on this topic on EVDL http://www.evdl.org/archive/index.html on the topic titled "Enerdel Battery Experiences", but you need to start at Page 2 before they get into the nitty-gritty of temperature and battery life discussions. Sorry, I don't know how to link to that specific thread.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

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