Charging the I MIEV @ 6.6 Kw instead the nominal 3.3

[fondi]

Can this be done by the dealer? Is it a software issue or the hardware on the I MIEV cannot take the 6.6 Kw current flow from a 240-30 amp EVSE?
This would reduce the charging time from 7 hours dow to 4 hours like the 2012 Nissan Leaf.
Thank you in advance.

Fondi
:|

 

[JoeS]

I'm confused: since when does the Leaf have a 6.6kW charger? Also, their charge time from empty is longer than ours because of their larger battery pack, even though their charger is slightly more powerful.

To answer your question, our iMiEV draws a little over 3kW and the charger hardware design is limited to around 15A as far as I know. Definitely not a dealer-adjustable item at this point in time.

The Leaf's charger is slightly more powerful than our iMiEVs, as I measured around 3.6kW going into my neighbor's Leaf.

 

[FiddlerJohn]

...reduce the charging time from 7 hours down to 4 hours...
:|

It's the hardware. The charger hardware in the iMiEV can't do any more than 3.3 kW. The software knows it and tells every EVSE it meets.

If you are L2 charging more than 5 hours most nights, you're in trouble. The iMiEV battery doesn't like to be deep cycled every night.

I plan to dip below 3 bars (SOC~12% for 2 bars) for as little time as possible.

 

[fondi]

Thanks for the reply guys.

Fondi

 

[fjpod]

...reduce the charging time from 7 hours down to 4 hours...
:|

It's the hardware. The charger hardware in the iMiEV can't do any more than 3.3 kW. The software knows it and tells every EVSE it meets.

If you are L2 charging more than 5 hours most nights, you're in trouble. The iMiEV battery doesn't like to be deep cycled every night.

I plan to dip below 3 bars (SOC~12% for 2 bars) for as little time as possible.

I've read the imiev lithium batteries are better suited for more frequent chargeing cycles than other manufacturers. If ones drives the car 70 miles per day and needs a nearly full charge every night, how is that bad?

 

[FiddlerJohn]

I've read the imiev lithium batteries are better suited for more frequent charging cycles than other manufacturers. If ones drives the car 70 miles per day and needs a nearly full charge every night, how is that bad?

You are correct. The iMiEV batteries are different and better suited for more frequent charging cycles than other manufacturers. Maybe more the twice the charging cycles, but that was in a lab report not the real world. Lithium batteries are stressed by deep cycles and storage at full charge. That will age the battery more quickly than less deep cycles and less time at full charge. By "age," I am referring to the natural loss of capacity over time. All lithium batteries loose capacity over time.

I expect to loose about two percent capacity per year even though I minimize deep cycles and storage at full charge.

 

[fjpod]

I've read the imiev lithium batteries are better suited for more frequent charging cycles than other manufacturers. If ones drives the car 70 miles per day and needs a nearly full charge every night, how is that bad?

You are correct. The iMiEV batteries are different and better suited for more frequent charging cycles than other manufacturers. Maybe more the twice the charging cycles, but that was in a lab report not the real world. Lithium batteries are stressed by deep cycles and storage at full charge. That will age the battery more quickly than less deep cycles and less time at full charge. By "age," I am referring to the natural loss of capacity over time. All lithium batteries loose capacity over time.

I expect to loose about two percent capacity per year even though I minimize deep cycles and storage at full charge.

So, if you are correct, wouldn't it be "healthier" to charge the miev, or any EV for that matter, slowly, with simply a 110 volt charger? Assuming one has the time to wait, of course.

 

[fjpod]

Found this about the imiev traction battery:

More Powerful, Faster Charge Time
Toshiba says the SCiB pushes the life of the lithium-ion battery to a new level by supporting two-and-a-half times more charge/discharge cycles than a typical lithium-ion battery. Recharging is also notably better. Charged with the highest current available with the so-called CHAdeMO charging technology, which is widely seen as the emerging standard for fast charging electric vehicles, an SCiB reaches about 80 percent of full capacity in some 15 minutes, about 50 percent in 10 minutes and about 25 percent in 5 minutes. All times are for a battery with a capacity 10 kilowatt-hours. A Nissan Leaf, for example, uses a 24-kWh battery and can travel approximately 100 miles between charges. By comparison, the SCiB requires half the charge time of a typical lithium-ion battery charged under the same conditions. The SCiB also generates little heat while recharging, eliminating the need for power to cool the battery module.

Most important of all for real-world application, Toshiba claims, the SCiB delivers high level performance. The SCiB offers a higher effective capacity than a typical lithium-ion battery, in that more of the stored charge can be used safely before recharging the battery. This, combined with highly efficient regenerative charging during braking or coasting downhill, allows the SCiB to deliver a claimed 70 percent more driving distance per level of charge of a typical lithium-ion battery. This will allow for installation of smaller battery modules in vehicles and contribute to lower electric-vehicle prices, Toshiba says. The SCiB also offers high level performance in a wide range of temperatures, and continues to support rapid charging and excellent power output at temperatures as low as -30 degrees Celsius (-22 degrees Fahrenheit).

 

[FiddlerJohn]

1. ... wouldn't it be "healthier" to charge the miev ... slowly, with simply a 110 volt charger?

2. Toshiba says the SCiB ... The SCiB also generates little heat while recharging, eliminating the need for power to cool the battery module.

3. The SCiB offers a higher effective capacity than a typical lithium-ion battery, in that more of the stored charge can be used safely before recharging the battery.

Yes, I agree on all points; however:
1. The SCiB is designed to be charged and discharged with hundreds of amperes at over 300 volts. Over the life of the battery difference between a 1 kW and 3kW charge rate is insignificant for longevity. The SOC and number of cycles is more important.
2. Notice that "Toshiba says" these things. Mitsubishi is silent but still uses the A/C to cool the battery. These are lab results and calculations. Your mileage will vary in the real world.
3. I'm convinced that the SCiB is best EV battery ever made, but I still intend to minimize unnecessary stress.

 

[Don]

I wouldn't want a 6.6 Kw charger even if it was free

I think there are several things one can do to improve battery life. Certainly avoiding regular deep cycles is a good idea . . . . not leaving it sit at 100% charge may be beneficial as well, but for sure slower charging rates are better than faster ones

If you need to drive it 100 miles per day or more, it's probably not the car for you as regular 'quick' charges are not a good idea. If you drive it 15 or 20 miles a day and can leave it on the 8 amp 120 charger overnight every other day, I think you'll probably wind up with a battery that lasts a long time

Myself? Ideally after 6 or 7 years my battery will fail under warranty and they'll replace it with one of the newer technology ones - Not likely however. I would guess if you got a warranty battery replacement, it would be with a refurbished L-ion battery which would last just long enough to cover the remaining warranty period

Don

 

[FiddlerJohn]

... leave it on the 8 amp 120 charger overnight ...

You are correct in using fewer charging cycles and not topping off the battery every night unnecessarily. That can reduce stress on the battery.

Another way to reduce stress it to minimize the time outside the 40% to 80% SOC range.

Below 40% SOC:
When I finally got home after getting lost on my 73.8 mile goose chase yesterday with 8 miles RR, I was eager to start charging at my highest rate (~3 kW) to minimize the time below 40% SOC. If I used the Mitsubishi supplied wall wart, the time below 40% SOC would have been much more.

When I brake the ECO gauge indicates charge of at least 50 amperes of current at 330 volts. That's 50 x 330 = 16500 Watts (16.5 kW) of charging. When I accelerate the ECO gauge indicates at least 150 amperes of current at roughly 330 volts. That's 150 x 330 = 49500 Watts (49.5 kW) discharging. That makes even 6.6 kW seem pretty small.

Above 80% SOC:
If I need a full charge, I can use the key FOB timer to minimize the time above 80% SOC. If I charge with three times the current (3 kW instead of 1 kW) I can reduce the time (and therefore the stress) over 80% SOC by a factor of three.

I don't know how much longer the battery will last by reducing the stress outside the 40% to 80% SOC range, but I know that a higher charging current (and a timer) can help me reduce the time outside the 40% to 80% SOC range.

 

[Don]

When I finally got home after getting lost on my 73.8 mile goose chase yesterday with 8 miles RR, I was eager to start charging at my highest rate (~3 kW) to minimize the time below 40% SOC. If I used the Mitsubishi supplied wall wart, the time below 40% SOC would have been much more.

I don't know how much longer the battery will last by reducing the stress outside the 40% to 80% SOC range, but I know that a higher charging current (and a timer) can help me reduce the time outside the 40% to 80% SOC range.

I'm not an electrical engineer (I haven't even played one on TV) but I doubt your logic here holds water - Slapping your highest available charge level on a severely depleted battery pack can't be 'better' for it than using the slow charging 'wall wart'

Fast charging generates more heat than slow charging and heat is always the enemy of batteries. Your battery was likely pretty warm when you returned from your drive. If I needed to fast charge it, I would have let it sit for an hour or so to cool off before I hit it with 3kw

Opinions may vary - Hopefully one day we'll have a real EE here to help us with such discussions

Don

 

[JoeS]

Opinions may vary - Hopefully one day we'll have a real EE here to help us with such discussions.Don

You don't need a EE - you need a chemist specializing in Lithium-xx battery design.

We have a number of different issues here, and FiddlerJohn's concern at leaving the battery at a low SOC and not wanting it to dwell there is different from the original topic of charge rates. I don't know the answer to FiddlerJohn's concern, although I personally prefer slow charge rates irrespective of SOC.

We recently had the chief scientist for a local Lithium battery R&D company give a presentation at a local Electric Auto Association meeting. After much discussion about rapid charging rates and battery heating I asked him point blank about the opposite: "Are there any issues in charging the battery too slowly?" After recovering from his shock at this seemingly-silly question, he allowed that there we no problems at all at the lower end and we could charge as slowly as we wished with not only no adverse effects but benefits from negligible battery warming from this charging rate.

At the upper end, do the math: yesterday we had a demonstration of the first truly high-powered CHAdeMO charging station at 50kW. If they are indeed stuffing all that power into our nominal 330v battery pack (which I doubt) that would mean 50,000kW/330v = 151.5Amps DC

By contrast,

Level 1 using the Mitsu (Panasonic) EVSE: 120vac*8A=960W
If we generously assume 90% charger efficiency, that means we have 864W available to charge the battery.
864W/330V = 2.6A going into the battery when charging Level 1

Level 2 EVSE: measured 3060W
90% charger efficiency means 2754W available
2754W/330V = 8.3A going into the battery when charging Level 2

Compared to the iMiEV's >100A regeneration current we've already measured and the CHAdeMO 150A charging possible, our low household Level 1 and Level 2 charging rates are an order-of-magnitude less.

The original question dealt with 6.6kW vs. 3.3kW, and the answer is that the onboard iMiEV charger is not designed to put in 6.6kW and in practice seems to draw a typical 3060W at exactly 240vac.

 

[fjpod]

I can live with 3.3. Right now I charge on 120 volt every second or third night. For what I use the car for, I rarely exceed 30 miles per day.

I can understand others that may need to recharge in the middle of the day. But remember, the more people charge in the middle of the day, the more stressed our electrical grid gets, especially in places like NYC. The more we have to burn dirty fuels to supply enough juice, the less environmentally sound EVs are. IMHO, EVs are designed to be charged at night when everybody is asleep.

 

[Don]

I was quite surprised to see that even using the 8 amp factory charge cord generates enough heat in the pack to have the cooling system kick in for 30 seconds or so every 4 or 5 minutes - I didn't expect that. I assumed such a piddly little charge would generate next to no heat

That said, at the first opportunity I'm sending the factory cord off to EVSEupgrade.com to have it modified for 13 amps. Based on what we've seen so far, that will probably be enough for 95% of our needs. I do have a 240 plug available in the garage for those rare times when I need it recharged more quickly

We drove it a total of 70 miles over the past 3 days, down to 2 bars and 11 miles remaining - Mostly around town at 40 or 45 but also about 4 miles down the freeway . . . . all with the A/C operating comfortably if somewhat frugally. Anyway, the recharge at 8 amps took 17 hours. Extrapolating that to a 13 amp charge should be something under 11 hours and that would work for us almost all the time

We always charge overnight, though we pay the same rate for electricity no matter the time of day - Right at 12 cents per kwh. I suspect in the not too distant future, we will have different rates for day and night . . . . we have a pretty big A/C load here along the Gulf Coast

Don

 

[Vike]

Found this about the imiev traction battery:

More Powerful, Faster Charge Time
Toshiba says the SCiB pushes the life of the lithium-ion battery to a new level by supporting two-and-a-half times more charge/discharge cycles than a typical lithium-ion battery. Recharging is also notably better....

I just ran across this thread while searching for information on Mitsu's plans for deploying SCiB. As we've clarified elsewhere on this board (but repeating here just in case someone's run across this discussion during their research, as I did):

The current Mitsubishi i-MiEV does NOT use Toshiba SCiB batteries. The current batteries are manufactured by a joint venture between Mitsubishi and GS Yuasa.

Mitsubishi has signed with Toshiba to use SCiB in future EVs, perhaps including a future version of the i-MiEV. With any luck, if the i survives in the U.S. market, perhaps we'll see those in 2013/2014.

 

[yellowwaterdog]

If you are really concerned (I am not), avoid charging your Li-ion batteries to 100% SOC. The primary failure condition of Li-ion batteries is time at 100% SOC. Avoid storing a Li-ion battery at 100% SOC and it will improve (statistically) the durability.

BTW, 6.6kW L2 requires a new on board charger and supporting software -- definately not dealer installed items!

Oh, DC Quickcharging is controlled by the vehicle to prevent abnormal damage to the battery -- remember, all batteries wear out eventually.....again, I am not concerned and charge on a CHAdeMO charger frequently.

 

[EVMOTO]

Hi,
here are some facts about the i-MiEV:

The i-MiEV is sold outside Japan only with 16kWh battery YUASA
In Japan, the customer can choose between 16kWh Yuasa and 10.5 kWh Toshiba SCiB.
http://techon.nikkeibp.co.jp/english/NEWS_EN/20111103/200392/

The charger provides up to 3.3 kW and operates in the range of 100-265 V with a maximum of 16A
While the charger has to be cooled, but there is a water cooler and you can hear the water pump from the left back of the car.

The battery does not become warm in this charging method, because the charging current for the 50Ah cells is too small.

The battery only becomes warm when being charged with CHAdeMO. A maximum flow 125 A (50 kW DC)
During charging at CHAdeMO always an additional fan cools the cells. This fan is mounted in the battery. From the outside, you can hear this fan (on the left side below passenger room)

In addition in hot summer temperature the air conditioning is activated when the battery is too hot during charging. The cooled air is fed directly to the battery

I hope this gives some clarification.

 

[gatedad11]

Question about 80% charging:
It appears that Nissan recommends not regularly charging past 80% full. Reading this forum, there has been some reference to fact that it's better to not charge over 80% on a regular basis, too, but it doesn't seem to generate the same level of concern as I am seeing on the My Nissan Leaf Forum. Are the batteries that different? Is there less risk with the I's battery pack as compared to the Leaf's? Right now I charge on 120V overnight and wake up at 100%(which my car tells me is around 73 miles, typically). Any advice?

Thanks,

 

[MLucas]

Question about 80% charging:
It appears that Nissan recommends not regularly charging past 80% full. Reading this forum, there has been some reference to fact that it's better to not charge over 80% on a regular basis, too, but it doesn't seem to generate the same level of concern as I am seeing on the My Nissan Leaf Forum. Are the batteries that different? Is there less risk with the I's battery pack as compared to the Leaf's? Right now I charge on 120V overnight and wake up at 100%(which my car tells me is around 73 miles, typically). Any advice?

Thanks,

There is a lot of debate about this. The engineer's on this forum will come along and give you specifics. I need my 100% everyday, so I charge up. The owner's manual doesn't refer to anything about not charging past 80%. Also, the Leaf has a 'Battery Saver' function that will stop the charging process at 80%, we do not have that option. My thinking is that since Mitsubishi has not provided this function and does not refer to this in the owner's manual that it is quite okay. However, I would ensure you use it as soon as possible and not let it sit for too long at 100%. This has been mentioned many times in previous discussions on this topic. I delay my charge until early in the morning and then drive my car within a few hours of reaching full charge. If I plan to not drive the car for a few weeks, like while on vacation I'll let it sit with half charge. I believe storage is mentioned in the owners manual and refers to a half charge or there abouts.