Battery degradation

[DenisTyumen]

Established conventional heating cable 220 V under the battery. While the car is standing near the wall outlet, it greatly helps for battery charging and for the preservation of regenerative braking at temperatures below -5 ºC
https://www.drive.net/l/5360202/

 

[Zelenec]

From the estonian article:
"Erreline told that if at the beginning of the summer was the time to drive at least 110 miles, it now becomes a maximum of 60 km - this despite the fact that this year's warm winter..."

Estonian not to hot summers don't often require to use the AC, so those I-mievs can average high ranges, but for sure not "at least" 110 miles. In winter time, even the range of the new car can easily drop to 60-70 kms with the use of heater and AC and fast driving. So such comparison is a sign of total ignorance or attempt to mislead.

Sure all batteries will suffer range drops. Perhaps the cars not owned by their drivers even faster. But to compare summer and winter ranges is kind of stupid.

My battery lost about 10% in three and half years and after 60k km. I expected greater loss, since I live in sub Alps Mediterranean country with relatively cold winters and hot summers. I charge at home everytime to full SOC and very often not only see the turtle, but even go to "notmoving" SOC. I sure can not join the conservative I-miev drivers club.

So, no reason to be worried. Our cars will have a long and happy life, at least till the warranty period expires.

 

[jray3]

Established conventional heating cable 220 V under the battery. While the car is standing near the wall outlet, it greatly helps for battery charging and for the preservation of regenerative braking at temperatures below -5 ºC
https://www.drive.net/l/5360202/

The auto-translations are always amusing, but if I read it right, you drove 80 km in -30 degrees Celsius, the last 5 km on turtle, and the recharge with battery heating only consumed 15 kWh?
(for us former colonists still measuring by the king's foot, that's 46 miles to turtle at 22 degrees below zero Fahrenheit!)

Impressive!

 

[DenisTyumen]

you drove 80 km in -30 degrees Celsius...

Yes I Do! Exactly. And the "turtle" has caught fire in the parking lot of the house. I think if you solve the problem with interior heating, without using the energy of the traction battery, you can increase the range of up to a nominal 150 km.
Many in our country have to "break" the concept of eco-friendly electric car by installing fluid heaters. I decided to go more difficult by involving hydrogen as a fuel for EV.
Check out my board magazine. Perhaps what ideas will be useful! :lol:
https://www.drive.net/r/mitsubishi/961201/

 

[peterdambier]

My record was 144 kilometers of range in summer two years ago.

Two days ago I got 142 kilometers and it was around freezing. That is range not kilometers driven. We have been driving some 50 kilometers, half of them uphill and I had forgotten our 2 kW fan and heater in the footwell. We had some 30 Celsius, more than 80 Fahrenheit when we took off and spent a nice day some 600 meters above the sea. Later 25 kilometers downhill to 230 meters above sea we used the heater to get us warm and a/c to keep the windows from fogging.

It is no doubt a heater can do wonders. Insulating all doors and lids back and front did help us a lot. It was terribly cold where we have been spending that day. I guess minus 5 Celsius, 20 Fahrenheit but for Karin and me that is not exactly "frette" but still awfully cold. The car was still warm when charging although it was 5 Celsius, 20 Fahrenheit outside.

Cheers
Peter and Karin

 

[Kuuuurija]

From the estonian article:
"Erreline told that if at the beginning of the summer was the time to drive at least 110 miles, it now becomes a maximum of 60 km - this despite the fact that this year's warm winter..."

Estonian not to hot summers don't often require to use the AC, so those I-mievs can average high ranges, but for sure not "at least" 110 miles.

Errata:
Kilometres, not miles.
Erreline told, that at first, when cars were brand new, just delivered, it was possible to drive 110 kilometres in summertime. It is not comparison of last summer range vs current winter range. This Winter we have mostly around zero degrees Celsius - it is record warm winter. Usually it is often -20 C and below in February here.
Erreline started to use iMiev in October 2011, so possibly her first summer distances were actually measured in 2012, when car was already ca 7 months old.

 

[jsantala]

Was there 110 km during summer on the RR when new or was he 110 km actually driven? What's the maximum RR seen now in summer temperatures?

I have a 2011 C-Zero, although only 15000km driven (had 10k, I've put in 5k in a few months), and it regurarly shows 105 km on the RR after some city driving and a full recharge.

Of course turning any heat on will immediately drop the RR to 70 km.

 

[Kuuuurija]

Was there 110 km during summer on the RR when new or was he 110 km actually driven? What's the maximum RR seen now in summer temperatures?

I have a 2011 C-Zero, although only 15000km driven (had 10k, I've put in 5k in a few months), and it regurarly shows 105 km on the RR after some city driving and a full recharge.

Of course turning any heat on will immediately drop the RR to 70 km.

110 km was actually driven.
I do not have any data about what was the maximum RR seen. Those cars were bought for social workers for everyday use, not for "who achieves max RR" competition.
Article says, that if the RR was initially 72 km, then after 30 km driven it dropped to 4 km. Main issue is, that actual range is dropping fast, car is almost useless after less than 3,5 years.

 

[JoeS]

This morning I took a relatively short drive in my new used i-MiEV, knowing it was going to be only about 15 miles. Even though I had forgotten to plug the car in last night, with 7 bars I figured I had plenty, although RR was indicating a disturbingly-low 20 miles IIRC. I was late, so I leadfooted all the way to my Jazzercise class (and its stunning blonde cheerleader…, but I digress).

Two stops after the class and I was ready to return home, disturbingly with 3 bars and five miles to get home and RR showing about six miles. Problem is that going home for me is uphill, so I really took it easy - this was in-town driving, no freeway. I got home with zero bars and RR=1 :shock: (but no turtle - I still have never seen it).

Pulled out CaniOn and it showed 11.0% SoC and 322v pack for the 14.9-miles! Air temperature around 60degF (16degC) - relatively mild due to the present Pacific storm. Here's the screenshot of the battery voltage:

Well, I decided to measure the L2 energy going back into the car using -
* kWhr meter
* T.E.D. (The Energy Detective)
* CaniOn

Results from 11.0% to 100%:
kWhr meter shows 12.8kWh
TED shows 12.93kWh
CaniOn :?

It took about 3 hours and 40 minutes to fill up. I would have expected six hours, based on past history with our other i-MiEV! RR was only 50 miles, reflecting my leadfoot driving.

CaniOn I didn't even look at the kWh and only took two screenshots (below) as I figured I'd have the data to download. Guess what - the bt_can database stopped on January 31, 2015 with only 12.2mb in it! :evil: I had done two thing:
1. I had inadvertently put the Android tablet into Airplane mode
2. I had upgraded to v.125 (see the CaniOn thread for further discussion)

Anyway, back to battery capacity: for the sake of argument let's say I put in 12.86kWh, ac input.

Using a charger efficiency of 88% from that Idaho Lab test report, that means that my pack, from 11% to 100% SoC, absorbed only 0.88*12.86 = 11.32kWh. Another way of saying this is that it took 11.32kWh to restore 89% of the battery's capacity.

Conclusion: 11.32/.89 = 12.72kWh is the pack capacity of my new used i-MiEV which now has 26,899 miles (hot climate car).

The TED screenshot needs a little explanation: the blue line is my L2 charger power draw. The first power draw is the other i-MiEV, whereas the second one reflects this recharge. It shows the magnitude, the requisite 'timeout' during charging, and the normal tapering during the final balancing. The red line is the voltage on one 120v leg of this split-phase circuit and the green line is my solar panels - today is a miserable rainy day (very very welcome here in California) so the panels are putting out zip. Ignore the yellowish line.

 

[Zelenec]

From my experience your result shows around 23% degradation.

16,6 kWh (from wall) 10% SOC to 100% SOC when my car was new.
12,8 .... your result after 27k miles
15,6 .... my last measured result last summer at 28k miles

Your consumption is a little higher due to longer charging time but not really so much to bring smile on face. I'm affraid your baby wasn't treated as needed before you bought her.

 

[tonymil]

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...ow-much-range-loss-for-electric-car-over-time

 

[JoeS]

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.

 

[jsantala]

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.

 

[pbui19]

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

http://www.academia.edu/6880205/Electric_vehicle_charge_optimization_including_effects_of_lithium-ion_battery_degradation

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]

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

 

[Vesilemb]

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]

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?

 

[JoeS]

Phximiev, thank you for posting. Anyone have an executive summary?

 

[Phximiev]

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/article/what_causes_lithium_ion_to_die

;-)

 

[JoeS]

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.