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The Battery Pack for Mitsubishi’s i MiEV
14 May 2008
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| The battery pack of the i MIEV. Click to enlarge. |
At the Advanced Automotive Battery Conference and Symposium 2008 in Tampa, Florida (12-16 May), Takuha Miyashita from Mitsubishi described the characteristics of the lithium-ion battery pack that Mitsubishi, in partnership with GS Yuasa, developed for the i MiEV (earlier post).
The i MiEV is powered by a compact 47 kW motor that develops 180 Nm (133 lb-ft) of torque and a 330V, 16 kWh lithium-ion battery pack. Top speed is 130 kph (81 mph), with a range of up to 160 km (100 miles) under Japanese 10-15 cycle driving conditions.
GS Yuasa Corporation, Mitsubishi Corporation (MC) and Mitsubishi Motors Corporation (MMC) launched a joint venture—Lithium Energy Japan—last December to manufacture large-capacity and high-performance lithium-ion batteries. (Earlier post.)
Battery-maker GS Yuasa is the majority shareholder with 51%; MC holds 34% and MMC holds the remaining 15%. Initial production is targeted at 200,000 cells in fiscal year 2009.
The 16 kWh i MiEV battery pack is installed under the base floor. The pack consists of 22 cell modules connected in series at the nominal voltage of 330 V—the high voltage helps deliver high power. There are two types of modules to enable efficient use of the limited space. Two 4-cell modules are vertically placed at the center of the pack and 10 8-cell modules are placed horizontally.
| Specifications of the i MiEV Li-Ion Cell | |
|---|---|
| Dimensions | 43.8W x 113.5H x 171D [mm] |
| Weight | 1.7 kg |
| Rated capacity | 50 Ah |
| Nominal voltage | 3.7V |
| Specific energy | 109 Wh/kg |
| Energy density | 218 Wh/L |
| Specific power (60-sec pulse at 25°C and 50% SOC) |
550 W/kg |
| Max output current @ 25°C | 300A |
Mitsubishi and GS Yuasa developed the cell for both high specific energy and high rate discharge. The newly developed prismatic cell used in the i MiEV pack has a specific energy of 109 Wh/kg and specific power of 550 W/kg. Energy density is 218 Wh/L. The entire pack has a specific energy of 80 Wh/kg.
The cell—and pack—feature high capacity retention at constant current discharges. Capacity at the high current of 200A is slightly less than at the lower rates (93.9% of capacity).
When discharged with an ambient temperature of 25° C, the pack is capable of delivering the maximum power from 80% DOD. Even at 0°C, the pack can deliver the maximum power from 70% DOD and enough power for propulsion from 90% DOD.
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| Pack capacities at 25°C. Click to enlarge. | 60-sec pulse power of pack. Click to enlarge. |
Mitsubishi tested the cycle life of the pack under standard (50 A) and quick charge (120 A) conditions using the JC08 driving pattern and found that the pack retained 84% of capacity with quick charging and 83% with standard charging after 1,000 cycles.
Development of the i MiEV EV concept began in 2005, and Mitsubishi is currently field testing units in Japan in cooperation with electric utilities, with market introduction slated for 2010. The company is also targeting market introduction in Europe and North America.
May 14, 2008 in Batteries, Electric (Battery) | Permalink | Comments (41) | TrackBack (0)
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Comments
Looks like 2010 is shaping up to be the big year for plug-in vehicles. Not sure what could derail the mass selling of plug-in cars and trucks in 2010. But considering recent history, I will believe it only when I can BUY one and keep it.
Posted by: Lee | May 14, 2008 8:25:51 AM
All the new cars are great but what about the
retrofit market? I have 2 vehicles that are paid off
and in good condition.
Is anyone designing EV retrofits? Gas just hit 3.99 a gal this AM. I can see 5.00/gal which means an investment in NON gasoline alternatives can now be looked at.
Something like an older Saturn SL1 or any cars with lower curb weight seems like good candidates.
Posted by: BobT | May 14, 2008 8:56:01 AM
Initial production is targeted at 200,000 cells in fiscal year 2009.
Obviously a lie -- Dr. Anderman says industry-wide production won't reach this much even by 2012. How can a single battery maker produce this much in 2009? Do they really expect us to believe such wild claims? Dr. Anderman is never wrong!
BTW, the battery curve shows noticeable degradation up a 3% highway grade, but many long grades in the US west are 6%. Of course i-MiEV is more of an urban runabout so 3% may be a reasonable design parameter. I still wonder if a 60-80 mile real-world range will sell in the US, though.
Posted by: doggydogworld | May 14, 2008 9:05:11 AM
BobT
Please check with MIRA (England) for ICE to PHEV retrofits
Posted by: Harvey D | May 14, 2008 9:16:55 AM
note that the scale on the left in the first graph only goes down to 250 V, not 0...
Posted by: lensovet | May 14, 2008 9:17:39 AM
dog: LOL ... I can see that the "good" doctor is going to take flak for quite some time.
Posted by: Neil | May 14, 2008 9:20:02 AM
It seems that the total number of cells could be (2x4=8) + (10x8=80) = 88 and not 22, to get 330 Volts unless a step-up converter is used.
Regardless of the number of cells, this seems to be a workable power pack. It could power the new GM Volt-PHEV-40 and other similar PHEVs.
First generation PHEVs seems to be on the horizon for 2010/11.
Posted by: Harvey D | May 14, 2008 9:27:47 AM
Yes, it's 88 cells. Power density is less than the Volt spec. Cycle life may also be an issue.
Is this battery lithium-cobalt-oxide? Kind of scary.
Posted by: doggydogworld | May 14, 2008 9:55:50 AM
In regards to MiEV climbing a steep grade slope, below is a link to the video.
Quote from a blog:
Unless I am interpreting the numbers incorrectly, it looks like the engineers take the iMiEV on a hill-climbing test run, from 663m (2,175 ft.) to 2,450m (8,038 ft.), a total vertical ascent of 1,787m (5,863 ft.) over a distance of 28.7km (18 miles).
Note:
Since I'm not allow to post links, please google the title: "iMiEV on display at Beijing Auto Show, climbs to summit in new video"
It has the link to the high quality video.
Posted by: Charles S | May 14, 2008 9:58:22 AM
[Well, I tried to post information about iMiEV climbing up the hill, but kept on being rejected due to spam filter.]
Mitsubishi site has a video of iMiEV traveling up some mountain roads. It was described as a vertical ascent of 1,787m (5,863 ft.) over a distance of 28.7km (18 miles). All that is on one charge.
Another site mentioned that he thought it had recharge all the electricity used from gliding downhill. I'm not sure I see that in the video, but overall, I'm pretty impressed.
Maybe the GGC will release my previous comments, and you can follow the links... Otherwise, oh, well...
Posted by: Charles S | May 14, 2008 10:04:13 AM
Looking forward to Mitsubishi releasing this little car here in the US. It would really be perfect for a City car (New York, Chicago etc.) and I hope they sell a ton of them. Unfortunately, the range and rear wheel drive means it won't be able to replace my commuter car here in the upper Midwest, although I'll still be seriously tempted..it is a cute little thing.
Posted by: Sasparilla | May 14, 2008 10:11:10 AM
I have to take back my comment on the range, if Mitsu can really deliver 100 mile range (real driving conditions, like with the air conditioning or heat on), this could replace my commuting car (I'd probably grin and bear the rear wheel drive since I don't drive every day). Come on Mitsu, roll this thing out and get it over here in the US.
Posted by: Sasparilla | May 14, 2008 10:42:36 AM
22 cell modules it says - so each module has 4 cells, probably with a common temperature sensor for the module. So 200,000 cells divided by 88 cells give us 2300 batteries per year.
Posted by: Emphyrio | May 14, 2008 11:18:35 AM
anyone else think its strange that the battery retains its capacity longer with fast charge than with trickle charge?
100miles x 1000cycles= 100,000 miles til 83% capacity. This pack is probably good for ~160,000miles before it becomes unusable.
If the chemistry is indeed lithium cobalt oxide (not advanced chem) then it should tell us the EVs are workable NOW.
Posted by: GreenPlease | May 14, 2008 11:25:10 AM
I doubt it is lithium cobalt if it is getting 1000 cycles in such an aggressive way... I wonder how many cycles you would get with shallow discharges?, lets say 10 miles daily.
Posted by: Herm | May 14, 2008 1:16:44 PM
That is a very heavy pack and a bloody large one too.
Alot of bev makers are squeaking into the 100 mile range as I expected they would by simply using absurd dod levels.. tho least this one isnt 100%.
Dont expect them to sell any more then they have to to make the various mandates as every one of these puppies is a big money loss and will likely require at least 1 pack replacement under warranty until they can improve the chem.
I only expect a few companies to realy try and push erevs and bevs and in the us all of them will wind up being made here due to the dollar and that locks these guys out for now unless they build plants in the us NOW.
Posted by: wintermane | May 14, 2008 2:07:46 PM
It is the nature of Lithium cells to do a "shallow" discharge.
A single cell is fully charged at 4.2 volts and if you discharge them below 3.0 volts, you may not be able to recharge them again.
Posted by: Lucas | May 14, 2008 2:56:21 PM
I understand the voltage characteristics of lithium cells.. by shallow discharge I meant only using 10-20% of the batterie's capacity instead of 80-100%.. that kind of usage would probably triple the life of the pack.. but the cells do age also, they may just die anyways in 3-10 years, even if you dont drive the car.
Posted by: Herm | May 14, 2008 3:35:15 PM
from a previous article they claimed 109wh/kg, or about 150kg for the 16kwh pack.. or equivalent to the weight of about 45 gallons of gas.
45 gallons of gas will be $200 soon :)
Posted by: Herm | May 14, 2008 3:39:32 PM
109Wh/kg is the cell itself.
The article states the entire pack is 80Wh/kg so closer to 200kg for the battery pack weight.
Posted by: Patrick | May 14, 2008 3:52:22 PM
The state of the dollar will not fundamentally change the market dynamics of Lithium batteries. Asian battery makers would still be able to assemble batteries at a better price point compared to US battery makers.
The impact would likely be carried by the automakers. They would have to go with smaller batteries than they would like, if they still care about prices.
Posted by: Lulu | May 14, 2008 6:05:11 PM
Remember the a123 batteries are 2/4td the weight and size snf they take up a huge space and are 160 kg after all the battery systems are counted. And we dont know the calander life of the cells.
As for making them in asia.. the dollar is already nuking profits and raising prices not to mention the fact oil is raising the cost of shipping...
Posted by: wintermane | May 14, 2008 8:41:05 PM
Let's see... Too much good news here. Let's catastrophize about money for a while. Hey, itza job.
Posted by: sulleny | May 14, 2008 10:31:41 PM
It will be a wonderful fad car for those who can afford it... but it likely over its life will eat 30 or more hybrid cars worth of packs... and be driven mostly by people who will still own hummers and highlanders... green all day black all night.
Posted by: wintermane | May 15, 2008 1:23:59 AM
The development of mass manufacturing for EV batteries such as this one will dramatically reduce the cost of HEV and PHEV batteries, leading to a reduction in HEV cost and wider adoption of HEVs and PHEVs.
Posted by: | May 15, 2008 4:54:14 AM
the market will allocate the distribution of batteries to hybrids and full blown BEVs, and it will do it most efficiently..
The best combination may be a short range BEV, lets say 20 miles, and an optional (hopefully removable) small generator... not the 50KVA monster that the Volt will use. Maybe 600cc like the original Mitsubishi car uses..or maybe smaller using a turbocharger. The important thing is that it must be optional, and while you are at it make the battery size optional also.. Versatility!
Posted by: Herm | May 15, 2008 5:34:25 AM
I like the layout of having the batteries under the floor. This low and center weight should bring the center of gravity to the bottom center of the car and really improve handling.
Also, it looks like they had the smarts to make the pack removable and easy to replace in the event that improvements in battery technology come to market.
I hope to see it available in my area soon.
Posted by: John Taylor | May 15, 2008 5:36:20 AM
I love this car. I don't know if I can wait to buy it though. I might get a Triac instead. $20,000 and available in a couple months.
Posted by: drivin98 | May 15, 2008 6:36:13 AM
For a small car with limited weight capacity, these batteries are disappointingly heavy, about 50% more than the Tesla's. Perhaps they're less expensive. Tesla's cost about $350 per Kwh storage.
If that cost were amortized over 100,000 miles (roughly 50 miles per day over six years), that would be a cost of about six cents per mile. The electricity would be two to three cents per mile, for a total "fuel" cost under 10 cents per mile, roughly the equivalent of 40 mpg at $4.00 per gallon. Drive less and your fuel cost goes up, since most of the cost is in the battery and not the electricity.
This doesn't count the cost of recycling. Modern day ICE drive trains are very reliable, and at the end of their life are easily recycled and are actually quite valuable as scrap. Batteries will be more problematic. There may be an end of life cost attached to a BEV.
Another problem to consider is that of running out of juice while far from home. It would only take a few powerless BEVs to totally block a freeway during rush hour. I would feel more comfortable with a built-in 5 Kw genset and two gallons of fuel for get-home power.
Posted by: fred schumacher | May 15, 2008 6:52:01 AM
@Fred,
Remember the deletion of the engine, coolant system, radiator, exhaust, emissions control systems, precious metal catalytic converter etc etc all offsets the "additional cost" of the battery, so it's not fair to look at the running cost of the battery alone. Rather you should look at the cost of the whole vehicle over 100,000 miles.
Also, remember that the servicing costs of an EV are going to be much lower than an ICE vehicle over 100,000 miles. That alone saves another 3 cents per mile for the EV.
Posted by: clett | May 15, 2008 8:03:55 AM
@fred:
Another problem to consider is that of running out of juice while far from home. It would only take a few powerless BEVs to totally block a freeway during rush hour.
What utter nonsense! What about cars running out of gas? Is that a problem nowadays? Cars out of gas clogging highways? Don't you think electric cars will have a battery indicator? And an audible warning when the charge level gets low, WITH an indication of how many km's can be driven on the resting charge? The year is 2008, not 1908.
Posted by: Anne | May 15, 2008 9:20:33 AM
@ Fred: This pack is 200kg. Tesla's is 450kg. Perhaps you are speaking of per cell mass per unit storage. Remember also that Tesla uses 18650 sized cells (2-2.5Ah) and this is 50Ah, so at least 20X larger per cell. When you integrate many cells, it adds weight, volume, and cost. Another key issue is that the pack is only 16kWh, so these cells may have been designed with more of a power bent with thinner coating on the electrodes, giving away some of the possible energy.
I'm excited to see a large format lithium pack going into production. I think this will facilitate a large drop in battery system costs down the road.
Posted by: Ben | May 15, 2008 1:00:46 PM
Where did you get the info that Tesla's pack is $350 per KWHR ?
Posted by: me2 | May 15, 2008 1:11:08 PM
Driving past the line of people at the gas station must be worth at least $0.25 a mile :)
Posted by: Herm | May 15, 2008 5:11:19 PM
@FRED - know this
When a BEV runs low on 'gas' you park it. Half an hour later you get back in and drive off. A 16Kwhr Pb-acid battery may give you three or four miles before it becomes undriveable again.
T2
Posted by: T2 | May 17, 2008 12:45:36 PM
You guys do not accept that the weakness of human spirit has caused the apocalypse that looms before us! Your electric cars will not help! Your bicylcists are insignificant, your FCL bulbs will make no difference! You all are F*&^ked!! Because you are arrogant. You think you should save the world when you cannot save yourselves. Fools!! Doom is upon you. Folly will reap cataclysm! And now...standby for a commercial break...
Posted by: deden | May 18, 2008 7:49:38 PM
Deden,
you don't seem to include yourself in the human race as you keep referring to humanity in the second person. Are you an alien or have you just evolved to a higher plane?
Posted by: critta | May 19, 2008 2:52:16 PM
Be careful, deden might be God. Filling stations will eventually become charging stations, quick charges will take maybe 10 minutes, even 20 minutes we can get used to. The important thing is get the ICE machines in the barn with the horse and buggy.
Posted by: Peacefreak | Jun 9, 2008 1:14:30 PM
Electric cars must be forbidden by law. All electric motor driven cars should be plug-in-hybrid; then no one could complain about the limited range or the lack of cheap high range batteries. Very small engines with high power to weight have been built for model airpanes for years and modern technology could give them even higher speed and power. TZERO employed motorcycle engines for its plug-in-hybrid operation. You can buy a two horse-power engine at a local model airplane hobby shop. This it enough to move any automobile at ten to twenty miles an hour. There is no reason to fear being stuck on the road away from home. Yes the engines can be engineered to have higher horse-power, low emissions and high efficiency and also to run on any fuel. See OPOC or RCV. High efficiency single piston engines could have heavy flywheels for vibration control and peak energy storage. Electronic vibration and sound damping could make their operation unnoticable. In the future,perhaps, tiny efficient microturbines could be built. Most of these spare engines would not need to be run often, even with low capacity lead batteries.
Electric cars have been possible since the the lead-acid battery and automobiles were first put together a hundred years ago. ZEBRA batteries have allowed the existence of long distance electric cars for over ten years. Lithium batteries are not needed for electric cars. ..HG..
Posted by: Henry Gibson | Aug 7, 2008 3:06:31 PM
By the time your typical recharging station is installed,3 phase,oodles of amps capacity,don't be surprised in order for the filling station to recoup his investment and make a profit,he would probably have to charge at least 75 cent per KWH,and where does that put you trying to save on transportation cost?
Posted by: HHN | Aug 20, 2008 10:31:48 AM
The batteries can be charged from a standard 15 A/200 V car charger in seven hours :
15x200 = 3000 watts for 7 hours : 3KWh
66% of us use fossil fuels to generate electricity.
Modern coal fired stations (not latest designs yet to be built) assume 1000g per KWh
So MiEV from coal fired Power Plant: 131 g/km CO2
Compare that to the 1999 Audi A2 1.2 TDI: 81g/km and 93mpg (uk). The latter can run on biofuel (GEN2 would be best).
Some 1.6 billion people, about one quarter of the world?s population,
have no access to electricity today.
Good effort from Mitsubishi but overall where's the progress?
Posted by: ecojet | Nov 23, 2008 2:45:59 PM
