Long Distance Travel Battery Thermal Concerns

[kiev]

... The i-MiEV really wasn't designed for travelling more than 100 miles a day.

i totally agree--the seats are very uncomfortable and any more than 30 miles at a time is painful. Plus lack of arm rest and cruise control is another PIA.

 

[JoeS]

... The i-MiEV really wasn't designed for travelling more than 100 miles a day.

i totally agree--the seats are very uncomfortable and any more than 30 miles at a time is painful. Plus lack of arm rest and cruise control is another PIA.

:shock: In the numerous 150+-mile days in the i-MiEV, I hadn't even noticed those perceived deficiencies. Perhaps my standards are different than yours, and I certainly would not characterize the seats as "very uncomfortable" nor the other two missing items as "PIA".

Back on topic, what would be nice is that whenever any of us do anticipate spending a long day driving, then perhaps we can record the CaniOn readings and post them like RobertC did. Starting and ending and ambient and battery temperatures, charging duration and power levels, and average speeds and type of terrain. It's the cumulative effect of incessant driving-and-charging that's the concern.

It also occurred to me that topography will have an impact on battery temperature: driving an average 40mph on the level is very different than climbing 2000' at 40mph followed by regenning at 40mph on the way down.

 

[RobertC]

While I can agree with that, how much effect is had by the AC blowing cold air into the pack while quick charging?

In order to have any heat transfer from the battery to the surrounding air, the air must be at a lower temperature than the battery, so blowing cold air while DC Quick Charging is better than allowing the hot air to build up in the battery compartment. While driving, the 88 LEV-50 batteries are generating their own internal heat from the current passing through them and their shape (rectangular prisms without much surface area) limits the amount of heat they can dissipate to the surrounding air.

Back on topic, what would be nice is that whenever any of us do anticipate spending a long day driving, then perhaps we can record the CaniOn readings and post them like RobertC did. Starting and ending and ambient and battery temperatures, charging duration and power levels, and average speeds and type of terrain. It's the cumulative effect of incessant driving-and-charging that's the concern.

I drove 190 miles in May 2014, stopping four times to DC Quick Charge, with approximately 1 hour of charging and 5 hours of driving.
http://myimiev.com/forum/viewtopic.php?f=9&t=2175
My beginning battery temperature was 17ºC (62.6ºF) and my ending battery temperature was 39.3ºC (102.7ºF). The ambient temperature was about 70ºF that day and I averaged around 40mph on mostly flat terrain. Bottom line is that if you keep pumping amps through your battery it's going to get hot. Electrical equipment and electronics that cannot tolerate high temperatures have heat sinks, the MiEV batteries do not.

BTW, it was my intention when I started this thread to discuss concerns about using the i-MiEV for continuous long-distance travel and not the occasional CHAdeMO quick-charge zap.

I only drove 190 miles as a test, as most of our family's single-trip driving is less than 50 miles. (98% of all single-trip journeys in the US are under 50 miles). We put about 15,000 miles a year on our two i MiEV's taking short trips.

With a range of 62 miles, the Mitsubishi i MiEV was not designed nor intended for continuous long-distance travel. It was designed for short trips. The high cost of using DC Quick Chargers helps discourage frequent usage and that helps the chargers be available for those wishing to use their EV's to take the occasional long trip. I found it inconvenient to keep stopping to quick charge on my 190 mile trip, and for there to be widespread adoption of electric vehicles it is important that charging is convenient. Our family loves how convenient the MiEV is: easy to charge at home, easy to park, zippy in traffic, and great for hauling cargo. The upcoming Tesla Model 3 with a projected range of 200 miles would be much better suited for those needing to take more frequent long trips.

 

[rkarl89203]

OK.
I understand.
No fun allowed.

 

[JoeS]

OK.
I understand.
No fun allowed.

Sincerest apologies if you took offense. I don't think any was intended. Here's some really long-distance fun in a C-Zero (none-the-worse for wear):

http://www.thechargingpoint.com/news/Around-the-world-in-a-Citroen-C-Zero-electric-car.html

 

[rkarl89203]

The downright unfriendliness of this particular thread is stunning. I simply told of my experiences and was inferred that I was running the car hard to 'make the battery fail.'
Really?
Seriously?
I am an I-miev booster.
I am PROUD of this car.
Gone from this thread but cmon guys, it's OK to actually enjoy our cars.

 

[Don]

The downright unfriendliness of this particular thread is stunning. I simply told of my experiences and was inferred that I was running the car hard to 'make the battery fail.'

I'm sorry, but I don't see that at all - I went back and read through every post, trying to see what you say you saw. I think it may be a matter of perception on your part

I don't see any 'unfriendliness' here toward you or anyone else. No one 'inferred you were trying to make your battery fail' - You asked what good is the car if you can't drive it and you got a great answer . . . . use it as you like, but keep in mind it wasn't designed for several days of long trips interspersed with several QC sessions per day (your planned 3,000 mile trip)

You came into this thread thinking that since you lived in the mid-west, there wouldn't be any battery heating issues for you, no matter how you used the car. I think you learned something from the friendly folks here - We all learn lots from those who have been monitoring their cars with Canion for the past 18 months or so . . . . I know I have

Don

 

[PV1]

Sorry if you took offense. I'm sure none was meant. Expressing opposing opinions without sounding rude or hostile is tough in text. The expression of how the sentence was said doesn't convey.

I guarantee there are owners that have a lot of fun with their cars, running temperatures and amperages that would make some of us cringe at the thought, and haven't experienced any issues. Many of us are taking extra precautions to try to make our packs last as long as they can. The most difficult thing at this time in the EV revolution is uncertainty of lithium ion and how long cells in different conditions will actually last. I think what scares us is the uncertainty of obtaining a replacement pack in the future, based on Mitsubishi's track history of how they treat the US i-MiEV market. If Mitsubishi can prove that driving habits drove the pack to failure, they may deny warranty coverage, whereas conservative driving has no doubt that driving habits didn't cause it.

For our batteries, a bad day in an EV beats a good day in a cell phone. To each his/her own. Have fun.

 

[Phximiev]

I think every iMiev owner should come to Phoenix in the summer. Today, it was 111+ and we were running around just fine (with the AC on full blast). Sure, we didn't want to go out....(cringe), but, we still got all of our trips done.

Then you wouldn't worry about heating up your batteries, ;-) , because both you and the batteries would be boiling.

Don't forget to bring your Budge's. You'll need them.

 

[Malm]

I' am having fun twice. :lol: . Having fun driving the car (geting 175 km mRR, doing one of the longest trips with one charge ever - 201 km, driving it to the highest point of Portugal), and I´m having fun understanding the car. And I love to share my findings with people all over the world. So, we are al having fun with our I-MiEVs.

 

[DonDakin]

Well I did another road trip. 302 KM (188 Miles) total distance four QC of about 30-80% about 65% highway and 35% secondary roads.
I would have loved to show another map but I forgot to enable the GPS on the phone so the tracking did not work.
It was from Montreal to Valcourt to visit the Bombardier Museum.

My first Multi quick charge trip. There is good QC coverage in this area the QC are spaced at about 50 KM or 30 Miles so no range worries.

I was able to manage battery temps by running the A/C into the battery as I was driving. The Battery temp trend was slowly climbing during the trip but I think it was controllable by driving slower/drafting on the highway and pumping in the A/C to the battery. I feel a little more confident that I could run the imiev on a longer run and manage the battery temp.

I averaged 62 KPH (39 MPH) moving and 46 KPH (29MPH) overall with the charge stops. Not steller but it was fun.

Here is a canion shot of battery temps you can see the cooling after each quick charge. The drop at the end was when I moved canion to the other imiev that had a cool battery already.

http://imgur.com/8bYb5ng

Don.....

 

[FrostyCanada]

Hello Don, do you manually direct the airflow to the battery pack like PV1, or do you let the car manage the flow as required?

Brian

 

[JoeS]

...I was able to manage battery temps by running the A/C into the battery as I was driving. The Battery temp trend was slowly climbing during the trip but I think it was controllable by driving slower/drafting on the highway and pumping in the A/C to the battery. I feel a little more confident that I could run the imiev on a longer run and manage the battery temp...

DonDakin, thanks for posting.

It took me a bit of head-scratching looking at your graph to understand that the battery temperature was rapidly spiking up during DCQC and that, with your judicious control, it was going down while you were driving.

Another question on the table:

Is there a mechanism whereby, DURING DCQC, it would be possible to force pump A/C air into the battery pack?

 

[Aerowhatt]

...I was able to manage battery temps by running the A/C into the battery as I was driving. The Battery temp trend was slowly climbing during the trip but I think it was controllable by driving slower/drafting on the highway and pumping in the A/C to the battery. I feel a little more confident that I could run the imiev on a longer run and manage the battery temp...

DonDakin, thanks for posting.

It took me a bit of head-scratching looking at your graph to understand that the battery temperature was rapidly spiking up during DCQC and that, with your judicious control, it was going down while you were driving.

Another question on the table:

Is there a mechanism whereby, DURING DCQC, it would be possible to force pump A/C air into the battery pack?

I find that even with the system pushing max AC into the pack for part if not most of the DCQC (which it does automatically) above certain battery temperatures (I believe the mid 80's F is where it kicks in right at the start of DCQC) the cell temps rise. Even with full AC provided by the system the battery temperature rises during DCQC. And without active cooling while driving afterwards like Don did, it will continue to rise.

Interestingly, even though the battery temp is rising, the AC (to the pack) is turned off by the system for the last few minutes of the DCQC charge cycle. I've been looking for a logical justification for this. Any ideas?

Aerowhatt

 

[pbui19]

I too am looking for ways to keep the AC control during DCQC. It seems the default AC on mode is dependent on the charging current. Once the current has tapered, the AC goes off. Even if DCQC session is restarted, the AC only runs briefly. As the sensor peak over 35C, I get too nervous and have to stop the DCQC.

 

[Palm35]

I unplugged the servo controlling the damper, loosened the screws, and flipped the damper manually. Now, anytime I direct air to the floor, it automatically goes to the battery......

I am interested by this solution, but I haven't understand what you have modified (and where)!
Could you put some pictures or a drawing view?

 

[DonDakin]

Hi Brian,

Yup i do it manually as described somewhere here on the forum with a picture also.

Joe sorry i didn't explain the graph more. But it is as you mentioned a spike of about 4 deg c during quick charge and then a taper down while cooling the battery.

I dont remember exact numbers but it looks like mitsu allows the battery to go well into 40 deg c I dont know if any hot climate member with canion can give us some data as to when the pwm battery exhaust fan comes on.

I am trying to keep the battery below 30 deg c if possible or rather use 30 deg c as a target value.

I think you can do this when the air temp is around 25 deg c.


As for forcing the ac on during qc perhaps it is possible by hijacking the compressor on command from the ac ecu to the compressor i think it might get complex because at lower temps the the fan does not go on during quick charge.

I guess its possible but you would need to study the schematics and do a few tests to see if you could control the compressor and the fan with some wiring mods. I think the simple manual flap control goes a long way.

Don......

 

[JoeS]

I unplugged the servo controlling the damper, loosened the screws, and flipped the damper manually. Now, anytime I direct air to the floor, it automatically goes to the battery......

I am interested by this solution, but I haven't understand what you have modified (and where)!
Could you put some pictures or a drawing view?

Discussed in a number of threads -

In Reference section: http://myimiev.com/forum/viewtopic.php?f=19&t=2681

http://myimiev.com/forum/viewtopic.php?f=14&t=1515

Photo here: http://myimiev.com/forum/viewtopic.php?p=12965#p12965

 

[JoeS]

More questions than answers -

In cars with CHAdeMO there is a fan inside the battery pack. It briefly turns on every time a J1772 EVSE is plugged in.

Independently, the car has the ability to route either cooled or heated air down into the battery pack from the car's climate-control system.

It is unclear to me that when the battery pack fan kicks in that simultaneously the aircon turns on and directs air down into that battery pack. Is that the case?

Whenever I've used CHAdeMO, I, too, was bemused that the battery fan would turn off before the charging completed.

DonDakin, on the Australian i-MiEV forum IIRC there was a discussion of high temperatures being measured in battery packs.

 

[Aerowhatt]

More questions than answers -

In cars with CHAdeMO there is a fan inside the battery pack. It briefly turns on every time a J1772 EVSE is plugged in.

Independently, the car has the ability to route either cooled or heated air down into the battery pack from the car's climate-control system.

It is unclear to me that when the battery pack fan kicks in that simultaneously the aircon turns on and directs air down into that battery pack. Is that the case?

Whenever I've used CHAdeMO, I, too, was bemused that the battery fan would turn off before the charging completed.

DonDakin, on the Australian i-MiEV forum IIRC there was a discussion of high temperatures being measured in battery packs.

"It is unclear to me that when the battery pack fan kicks in that simultaneously the aircon turns on and directs air down into that battery pack. Is that the case?"

I have not ever witnessed the Battery pack exhaust fan (towards the rear of the car) run except for the case you mentioned plugging in a J1772 EVSE. During this process the damper up front to the cabin climate control is sealed shut. So another question, is there make up air for what the exhaust fan is pulling out, and if so where would it come from? I say there isn't as the battery pack is pretty well sealed.

During DCQC my battery exhaust fan has never run. But the cabin AC runs at max into the ducting to the battery case until near the end of the charge, then it turns off (prematurely IMO). Since the exhaust fan does not have an actuated damper (just a coarse foam insert to keep debris and insects out) it would serve as the warm air exit for the pack while the cabin AC is being pumped through. Also, watching Canion cell temps graph I see no difference in the cooling of the pack with max AC during, or not during DCQC, reinforcing my perception that the battery exhaust fan does not generally run during hot weather "normal" DCQC (even if the AC does). Perhaps it would run as well with really, really high battery temperatures??

Aerowhatt