JoeS
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Location: Silicon Valley, California

Re: Battery temperature management

Fri Aug 02, 2013 11:15 am

siai47, I appreciate your posts and and enjoyed your description of the cooling diversion, as well as the jaraczs' photographs of the battery ducting. I also understand your frustration with having purchased a second iMiEV, only to find that it is missing all the battery ducting that your previous leased vehicle had. Your concern is quite evident in your various posts on this subject.

I submit that perhaps our iMiEV situation is less dire than the Nissan Leaf's. So far, the iMiEV seems to me to be a pretty-well-engineered car. Mitsubishi had significantly-more experience with electric cars than Nissan when they placed it on the US market, and I seem to recall reading somewhere that the iMiEV's cell internal resistance is less than the Leaf's (resulting in less internal heat generation under load). Mitsu's concern with batteries seems to be more related to low temperatures than high, perhaps a result of a battery chemistry formulation more favorable to high temperatures than Nissan's(?). The absence of forced-cooling (except for CHAdeMO-equipped cars) reflects this. Since, as was pointed out, the addition of this cooling ducting would have been a minimal cost item for them, I would think that their internal benefit-cost analysis would have erred to the conservative if they thought there might be an issue.

Nothing so far points to an iMiEV capacity-loss that Nissan has experienced with their Leaf in the extremely high temperature southwest US environment - quite frankly, even their situation is quite limited, and the Leaf owners' paranoia over losing some capacity is perhaps a bit overblown, IMO, they having the advantage(?) of vehicle instrumentation that can make them nervous. Reality is, that unless we have a fixed daily commute that pushes the iMiEV's range limits, it's really hard to quantify any capacity loss because of all the other variables that can affect range. Time will tell…

My reason for posting this is to try to allay an possible concerns that non-techies might be having as a result of this discussion. So far, nothing is pointing to any battery issues with our iMiEV, at all.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
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Vike
Posts: 401
Joined: Sun Jun 10, 2012 8:25 pm
Location: Albuquerque, New Mexico

Re: Battery temperature management

Fri Aug 02, 2013 11:38 am

JoeS wrote:My reason for posting this is to try to allay an possible concerns that non-techies might be having as a result of this discussion. So far, nothing is pointing to any battery issues with our iMiEV, at all.

Thanks for that. But though I bought my i-MiEV w/QC, this is still among the more depressing threads I've read in quite a while. Some of us (i.e., moi :oops:) could get pretty snooty at times about Nissan's battery-baking sealed box, contrasted with the clearly better thought-out air cooled/heated Mitsu battery pack. For it to turn out that this was just ignorant marketing hype, extolling the virtues of features that were in reality both less consequential than claimed and less widely available, is as much a black eye for MMNA as it is an embarrassment to those who believed their pap. And not to put too fine a point on it, but . . . now that we know they lied to us about this, one must wonder what ELSE they might have lied about.

Given the very misleading marketing materials and poor communications, if these cars do develop heat-related problems (which I dare hope they will not), Mitsubishi may find themselves on the wrong side of a (relatively tiny) class action lawsuit.
2012 Silver ES w/QuickCharge+DRL/foglights, Eaton Level 2 EVSE, since 9/9/2012

siai47
Posts: 363
Joined: Fri Jun 14, 2013 5:54 pm

Re: Battery temperature management

Fri Aug 02, 2013 2:26 pm

This discussion wasn't started to try to alarm anybody about how their I-MiEV will or will not perform in hot weather conditions. I started it after I had read several threads that mentioned the battery cooling system that was thought to be standard equipment on all I-MiEV's. I leased the first I-MiEV with the optional battery warming system and quickly discovered that it could be easily modified to allow cooling (manually controlled) if desired. Everything I had heard about the I-MiEV, had seen in sales literature and found on the internet seemed to point to the fact that at a minimum, there was a battery "fan" in the traction battery enclosure. I live in central Florida and in addition to the leased I-MiEV I had a leased 2012 LEAF which has now been replaced with a 2013. My mistake was to buy an additional I-MiEV and assuming all cars had some sort of cooling system. I was really suprised to find out the truth. I honestly believe that even the dealer thought this was the case. It wasn't until I got a service manual and technical information manual and went over the salesman's books that I found out the truth. Am I dissapointed? A little. Am I mad? No. I have owned several other EV's in my life including a Rav4-EV and a couple of Chevrolet S10-E's. Both had some sort of thermal management system that can be a blessing or a curse. The air-cooled Rav wasn't much of a problem and could be used in a closed garage. The S10's were nigthmares as the active system (Freon refrigerated) would run anytime the vehicle was plugged in even when not charging. It was impossible to park it in a closed garage and not come out later to find the A/C system cranking and the garage well over 110 degrees on a normal summer day. I felt I had found the perfect solution where I could park the I-MiEV in an air conditioned garage and then if the need to keep the pack cool arouse, I could provide cooled air to it. This works well on the leased car which I have been driving. The one I bought had 30 miles on it when I bought it---it now has 90. I am going to adapt something to cool the pack before I start to drive in hot weather. I know the Li-ion batteries (in fact all batteries) are happier at cooler temperatures. If you read Yuasa literature about the LEV-50 (which is the basis of our battery pack) they live a lot longer and produce the most energy at no more then 77 degrees--this is a fact from their own documents. The cycle life and calendar life also improves as you lower the temperature below 77 degrees. I have also found that a temperature above 86 degrees triggers the A/C into operation during QC. Therefore I need to minimize temperatures much hotter than that to insure long life. I know we have a 8 year battery warranty and that batteries degrade over time. With the short range that we already have with the I-MiEV I would hate to lose 20% or more faster then necessary. In summary, my intention wasn't to alarm the owners that come to this site, but to inform them that for those who have the warming system or QC have a simple way to possibly extend the life of their pack without any out of pocket expense or anything that could not be reversed and cause a warranty issue. It would be fine to lock this thread if you want or leave it open to further opinion.

RobertC
Posts: 292
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Location: Winter Garden, FL

Re: Battery temperature management

Fri Aug 02, 2013 2:39 pm

Vike wrote:
JoeS wrote:My reason for posting this is to try to allay an possible concerns that non-techies might be having as a result of this discussion. So far, nothing is pointing to any battery issues with our iMiEV, at all.

Thanks for that. But though I bought my i-MiEV w/QC, this is still among the more depressing threads I've read in quite a while. Some of us (i.e., moi :oops:) could get pretty snooty at times about Nissan's battery-baking sealed box, contrasted with the clearly better thought-out air cooled/heated Mitsu battery pack. For it to turn out that this was just ignorant marketing hype, extolling the virtues of features that were in reality both less consequential than claimed and less widely available, is as much a black eye for MMNA as it is an embarrassment to those who believed their pap. And not to put too fine a point on it, but . . . now that we know they lied to us about this, one must wonder what ELSE they might have lied about.

Given the very misleading marketing materials and poor communications, if these cars do develop heat-related problems (which I dare hope they will not), Mitsubishi may find themselves on the wrong side of a (relatively tiny) class action lawsuit.


The i-MiEV battery was developed by Toshiba and uses lithium titanate oxide in its anode.
http://www.toshiba.co.jp/about/press/2011_06/pr1603.htm
The following line is in the press release:
The SCiB™ also generates little heat while recharging, eliminating the need for power to cool the battery module.

The Leaf uses lithium manganese oxide. Here's a comparison test of A123's new battery that shows the Leaf's battery does not do well in the heat.
http://insideevs.com/a123-updates-next-gen-nanophosphate-ext-batteries-solves-lithium-battery-heat-issues/
The following line is in this article:
The competition, which is clearly the LMO (lithium manganese oxide) cells found in the Chevy Volt and Nissan LEAF , faired much worse, losing over a third of their capacity.
I still hold out hope that our batteries will stand the test of time.

It's also interesting to note that only the Mitsubishi Motors North America website makes these false claims about battery cooling.
I looked at Mitsubishi websites in the UK, France, Germany, Australia and Japan, and I do not see these claims on their websites.
I don't think that the battery cooling claims were on the website a year ago when I bought my i-MiEV.
I think that MMNA's website has been updated to make these battery cooling claims.
Perhaps MMNA just doesn't know that much about the i-MiEV.
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alohart
Posts: 377
Joined: Wed Apr 25, 2012 10:15 am
Location: Honolulu, HI, and Uppsala, Sweden

Re: Battery temperature management

Fri Aug 02, 2013 3:17 pm

RobertC wrote:The i-MiEV battery was developed by Toshiba and uses lithium titanate oxide in its anode.
http://www.toshiba.co.jp/about/press/2011_06/pr1603.htm
The following line is in the press release:
The SCiB™ also generates little heat while recharging, eliminating the need for power to cool the battery module.

This does not apply to i-MiEV's sold anywhere outside of Japan, and maybe not even those sold in Japan. The i-MiEV battery is manufactured by the Yuasa-Mitsubishi joint venture, GS Yuasa.

RobertC wrote:The Leaf uses lithium manganese oxide.

As does the i-MiEV.
Aloha,
Art
Honolulu: 2014 BMW i3 BEV (formerly 2012 i-MiEV SE)
Uppsala, Sweden: 2000 Honda Insight

Vike
Posts: 401
Joined: Sun Jun 10, 2012 8:25 pm
Location: Albuquerque, New Mexico

Re: Battery temperature management

Fri Aug 02, 2013 4:23 pm

RobertC wrote:The i-MiEV battery was developed by Toshiba and uses lithium titanate oxide in its anode.
http://www.toshiba.co.jp/about/press/2011_06/pr1603.htm
The following line is in the press release:
The SCiB™ also generates little heat while recharging, eliminating the need for power to cool the battery module.

The Leaf uses lithium manganese oxide. Here's a comparison test of A123's new battery that shows the Leaf's battery does not do well in the heat.
http://insideevs.com/a123-updates-next-gen-nanophosphate-ext-batteries-solves-lithium-battery-heat-issues/
The following line is in this article:
The competition, which is clearly the LMO (lithium manganese oxide) cells found in the Chevy Volt and Nissan LEAF , faired much worse, losing over a third of their capacity.
I still hold out hope that our batteries will stand the test of time.


Confusion on this point is recurring, so the standard reminder:

Toshiba's SCiB has been an i-MiEV battery option for some time now, but only in Japan. SCiB tech stores less energy per pound of battery, but has greatly improved tolerance for being slammed with DC quick chargers. If you L1/L2 charge overnight in your garage, want maximum range between charges, and don't have CHAdeMO stations in your area (i.e., you're a typical American EV owner), SCiBs have little to offer, hence they're not offered in the U.S. While it's also been reported that SCiB can take more charge/discharge cycles and degrade somewhat less over time, over the expected life of a U.S. market i-MiEV neither of these qualities are likely to be enough to compensate for the initial lower energy density and shorter range.

In Japan, where there's a fairly well developed network of CHAdeMO stations, SCiB's reduced range can be worth it if you are able to take advantage of CHAdeMO to quickly top it off, especially since you can safely do that more than once per day if need be. Japanese customers can choose which battery technology they would prefer based on their circumstances; I don't know if SCiB is extra cost.
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RobertC
Posts: 292
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Location: Winter Garden, FL

Re: Battery temperature management

Fri Aug 02, 2013 4:26 pm

alohart wrote:
RobertC wrote:The i-MiEV battery was developed by Toshiba and uses lithium titanate oxide in its anode.
http://www.toshiba.co.jp/about/press/2011_06/pr1603.htm
The following line is in the press release:
The SCiB™ also generates little heat while recharging, eliminating the need for power to cool the battery module.

This does not apply to i-MiEV's sold anywhere outside of Japan, and maybe not even those sold in Japan. The i-MiEV battery is manufactured by the Yuasa-Mitsubishi joint venture, GS Yuasa.

RobertC wrote:The Leaf uses lithium manganese oxide.

As does the i-MiEV.


Documentation?
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RobertC
Posts: 292
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Location: Winter Garden, FL

Re: Battery temperature management

Fri Aug 02, 2013 7:06 pm

siai47 wrote:It's possible you could use the remote to pre-cool the battery. However, I am not up to speed on the remote, but is seems the remote causes the A/C (or heat) system to default to some pre-configured operation. I don't know if it overrides the positions of the dash controls.

I tried the remote AC and the dash controls are ignored and the cold air only comes out the top vents.
I would think that it would be possible to have the AC put cold air into the battery pack when charging at L1 or L2, maybe 5 minutes every hour, when the pack temperature is above 86 degrees.
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siai47
Posts: 363
Joined: Fri Jun 14, 2013 5:54 pm

Re: Battery temperature management

Fri Aug 02, 2013 7:25 pm

Small point--it is a Lithium Manganese dioxide cell. The LEV 50-4 and -8's that are in our I-MiEV's are a slightly modified cell that originated from the Yuasa LIM series of commercial Lithium batteries. The first clue that we don't have Toshiba cells in our pack was that the largest Toshiba cell manufactured when our cars were built was a 20 AH cell. It also has different voltage characteristics from the LEV 50. There is no combination of 88 Toshiba cells that would give us a 16 KWH pack at 360 volts. There are also some talk that the batteries in the 787 Dreamliner are the same as the ones in the I-MiEV. Although they are made by Yuasa, they are a Lithium Cobalt cell. Documentation for this came from a Yuasa technical report on the development of the LEV 50 cell and from the material data safety sheets for the cell. The last clue as to what cells we have is that I dropped the pack in one of my I-MiEV's and looked.

fjpod
Posts: 529
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Location: NYC

Re: Battery temperature management

Sat Aug 03, 2013 3:25 am

One has to think that if MM went through all the trouble developing the cooling/heating system, but only put it into their chaedmo cars, there must be a reason...like, normal battery temps while charging/discharging do not need temperature management...for the battery size and chemistry that we have. We would probably waste more energy cooling our batteries than it was worth.

Again, no hard scientific facts here, but just considering what a group of rational engineers might do.

Consider a Tesla for a moment. They need a thermal management system because they dump so much juice into those massive batteries, that the lights dim in Peoria when a single person turns one on. (OK, I'm stretching it a bit)...but they do use so much juice. The Tesla actually has two charging ports that you must use simultaneously to get any kind of a reasonable charging time. and I think they each pull something like 50 amps, 200 volts.

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