Battery temperature management

[Vike]

Well, when it comes to the i-MiEV's lack of active air cooling, I've decided to:

- Stop picking on LEAFs and their missing battery cooling systems; we're in the same boat

- Do more of my driving with A/C off and the windows open; better for the battery and I prefer it anyway (but of course I'll continue to use A/C whenever that's more comfortable)

- Order in a set of wind deflectors; I like the way they look and they'll let me crack a window for air while still keeping the sun off

- Stop worrying about it; won't help, probably not a problem anyway

 

[siai47]

Vike, I noticed you have QC in your ES. You could easily cool your battery with the A/C system if you wanted to.

I found an interesting post from High-Tech Industry in Japan that's over a year old talking about a successor to our batteries which is called the LEV50N. One of the items mentioned is "The new product has higher durability in a hot environment----" It appears that these went into production after our cars were built and might be found in the new PHEV offerings. Link:

http://hightechindustryinjapan.blogspot.com/2012/03/no-458-longer-lasting-lithium-ion.html

 

[JoeS]

siai47, thank you for this link. Ooooh, batteries with high-temperature tolerance AND lower cost - maybe that's Mitsubishi's secret weapon for the future?

 

[aarond12]

I'm opening this can of worms again, because of yesterday's drive. I have an ES without CHAdeMO.

Yesterday, we had a typically hot Dallas day. I was on the freeway around 70-75 MPH with the air conditioning on. The temperature gauge showed 104°F (40°C).

When I pulled into the house, we had a lot of things to unload from the car. I left the car "running", but turned off the A/C. The fan in the front of the car, which typically shuts off immediately when I turn off the A/C, stayed on for another 5 minutes or so. Inside the car, I could faintly smell the odor of antifreeze (coolant).

Are we *certain* the ES doesn't use the A/C to cool the battery?

 

[siai47]

The electronics are liquid cooled in this order---Charger---inverter---motor. What you heard is the radiator/condenser fan running to cool off the antifreeze circulating in the coolant loop. It will run for a while to get the system cooled down. There is no battery cooling while driving regardless of what options you have on your I-MiEV. If you are smelling coolant, check the level of coolant in the bottle on the left side of the motor compartment (under the lid) and make sure it is up to the "full" level. If I was driving in temperatures like you are seeing, I would put a fan under the car in the garage to blow air underneath it to cool the battery some by convection.

 

[aarond12]

If you are smelling coolant... I would put a fan under the car in the garage to blow air underneath it to cool the battery some by convection.

I'll check the coolant level when I get home. This was the worst conditions I've driven the car in before (heat-wise), so I wasn't too surprised to smell coolant. I have a fan to exhaust the hot air from the garage, so it doesn't get way too hot in there. Maybe I'll put my box fan in front of the car after a hot drive like this weekend's. I rarely take the i-MiEV on the freeway even on cooler days, so this shouldn't be an issue in the future either.

Edit: The coolant level is at exactly "full" on the reservoir. I guess it's possible the coolant expanded enough to go into some overflow (possibly dumped on the road?!) for me to be able to smell it.

 

[RobertC]

I charged my i-MiEV yesterday at a Blink DC Fast Charger from 40% to 80%.
The air conditioner ran to cool the battery starting at 40%, but stopped running at 68.5%.
The battery pack temperature went from 28.6 degrees C (83.4F) to 31.6 degrees C (88.9F). The outside temperature was 75F.

Battery temperature at 40%. (Using CaniOn)

Battery temperature at 79% (Blink Charger said 80%)

Amps History showing the DC Fast Charge.

The total charge time was 13 minutes.
The total gain in range according to the range remaining meter was 38 miles.
The i-MiEV charged at over 40kW for the first couple minutes, after which the charger ramped down.

 

[fjpod]

If I am reading this right, battery temp does not rise much even under DC quick charge?

 

[peterdambier]

From what I have learned (mostly evtv.me and Lithium Iron Phosphate) charging with 0.1 C (10 hours), 1 C (1 hour) or even 10 C (6 minutes) a charge to 80% does not raise cell temperature very much but a charge above 90% even at 0.1 C or less does dramatically. That is why some people think charging above the point where constant current is changed for constant voltage does reduce cell life and quickcharging is actually better for the cells.

Another curious discovery was the algorithm that was meant to charge to 80% actually charged 90%.

They have got new cells with another technology and are experimenting with these too.

You put in some 7 or 8 kilowatt hours and temperature climbed some 3 celsius. Ok climate control helped a bit but that still looks very promising.

Thanks for sharing.
Peter and Karin

 

[RobertC]

I charged today at a Greenlots DC fast charger in Mount Laurel, New Jersey (the second fast charger to open in New Jersey) located about 40 miles from my house. The traction battery was about 40 degrees F when I started charging, and the DC fast charger only charged in the 40 to 50 amp range for the first six minutes of the charge.

Heres a closer look. After about six minutes the battery started to charge at about 77 amps before ramping down as usual.

Previously while DC fast charging, the battery would immediately charge at between 110 and 120 amps as soon as I plugged in. I'm not sure why this time was different? I couldn't find any documentation that shows the i-MiEV DC fast charges slower at 40 degrees F.

Also, it looks like the i-MiEV always stops DC fast charging at 80% state-of-charge. You have to restart the DC fast charger to charge more than 80%.

 

[PV1]

I couldn't find any documentation that shows the i-MiEV DC fast charges slower at 40 degrees F.

40 degrees F is about 4.5 degrees C. I've found below 14 degrees C, the i-MiEV starts to reduce regenerative braking force, so it makes sense that it would limit DC quick charge. When the battery in mine is about 11-12 degrees C, regen is capped at 28 kW, and reduces more as temperature drops.

One morning, I was driving to work with more than 94% SoC in 5 degree F weather. When I went to slow down, I had almost no regen, only going a little less than halfway in the blue zone. :shock:

 

[DonDakin]

I think the lower the temp of the battery the slower the charge. Roberts post is the first data I am seeing of this.

I think the charge rate is governed by the car to a safe value depending in battery temp. At high temps the a/c comes on to cool the battery but at low temps the current starts lower and as time goes by and the batteries heat up the charge rate increases. I don't have any documentation to back this up but it's my theory. In quebec they are studying the charge rates for L3 chargers at cold temps. I think this is why they are taking so long with the rollout of L3. It would be interesting to see canion data for cold weather L3 charging. I would provide some data myself but I have yet to get to our only L3 charger in quebec which is 40 km away.

Don.....

 

[PV1]

I agree with this. If the temperature gets too low, the car will heat the battery if equipped. On the 5 degree F morning I mentioned above, I gave the car 6.5 hours to gain 5 bars on level 2, 13 amps. When I went to preheat the car in the morning, it was still charging, although very close to full. Apparently the battery heater activated, causing the long charge time. However, the battery was still quite cold.

Looking at the current graphs for QC, it would seem that smaller quick chargers, 40 kW or maybe 30 kW, could charge the i-MiEV just as quickly as a 50 kW model, since the charger only spends a few minutes at full power. 50 amps is only 17 kW.

Same here, if I was comfortable driving 47 miles in the cold to the only quick charger in range, I could provide some data. I'm not concerned with the car making it, it's the availability of the quick charger, since it seems to be turned off randomly.

Robert, what was your starting SoC?

 

[RobertC]

Robert, what was your starting SoC?

My starting SoC was 42%.

Same here, if I was comfortable driving 47 miles in the cold to the only quick charger in range, I could provide some data. I'm not concerned with the car making it, it's the availability of the quick charger, since it seems to be turned off randomly.

The other DC fast charger in New Jersey is 50 miles from my house. I can definitely make it there if I turn the heater off and use my electric blanket that plugs into the i-MiEV's 12V accessory outlet to keep me warm. I also find it helps to travel on a sunny day to allow sunlight coming through the windows to keep the car warm. I have applied Rain-X Anti-Fog to the windows and found that it keeps them from fogging up. The other DC fast charger in New Jersey is part of the Blink Network and I can check their app to make sure the charger is available before I leave.

Checking the PlugShare app, it looks like the DC fast charger in Warrendale, PA at the Eaton Power Systems Experience Center has been working recently. You could check with them before you go.

 

[Malm]

All my story in http://www.nissanleafpt.com/viewtopic.php?f=32&t=1556&p=19713#p19713, in this page some interesting (I think) data I collect of temperature pack evolution in quick charges. In English too.

 

[JoeS]

All my story in http://www.nissanleafpt.com/viewtopic.php?f=32&t=1556&p=19713#p19713, in this page some interesting (I think) data I collect of temperature pack evolution in quick charges. In English too.

Happy New Year, Malm, and thank you for the post. For those unfamiliar with the technique, it's usually possible to translate something by copy-pasting the URL into http://translate.google.com/

 

[Malm]

I think my English is a little better then that of translation tools (no sure) :? . Good 2014 JoeS, and to you all.

 

[MLucas]

I couldn't find any documentation that shows the i-MiEV DC fast charges slower at 40 degrees F.

40 degrees F is about 4.5 degrees C. I've found below 14 degrees C, the i-MiEV starts to reduce regenerative braking force, so it makes sense that it would limit DC quick charge. When the battery in mine is about 11-12 degrees C, regen is capped at 28 kW, and reduces more as temperature drops.

One morning, I was driving to work with more than 94% SoC in 5 degree F weather. When I went to slow down, I had almost no regen, only going a little less than halfway in the blue zone. :shock:

I'm confused by this. 14 degrees C is not that cold, unless you are referring to minus 14 degrees Celsius. I've been watching my battery temp on my MiEVCan and its routinely between 12 and 18 Celsius which is a nicely warm battery. Even on the coldest days my battery temp is more than enough for efficient use of the battery. I've never had a day where the regen has been reduced and we've had a cold winter here so far with -10 Celsius outside temp (14 F) being the coldest I've seen so far. Which means the battery heating system won't activate until its -15 Celsius.

 

[acensor]

I have seen several coments in other posts about battery fans and battery temperature management on the I-MiEV. It's not clear in the sales literature or listening to videos from Mitsubishi engineers but I-MiEV's do not have any traction battery fan unless you have one of the two options---either the battery warming system or the quick charge port. The fan isn't used for any battery temperature management except in very cold temperatures (warming system or quick charge option) or during quick charge (cooling via A/C operation). If you have either option, you will hear the fan start for a few seconds each time you plug in the EVSE. .....

I don't have the quick charge port on our SE ... And have not reason to believe it has a Barry warming system (was sold off a dealer lot in a mild climate region of central California.)

When I plug it in i hear hums that sound like maybe a fan. And periodically intermittently similar sounds if I walk out into garage while it's charging. No fan? Then what are those sounds?
I thought there was. I even thought maybe liquid based temp management was going in at batteries. Is the coolant liquid system I see signs of under front hood only for the cabin heater?

Alex

 

[PV1]

This video shows what the battery fan sounds like. Turn your volume up.
https://www.youtube.com/watch?v=7p30lMFfVPI

This is the cooling pump, which you'll hear when charging and sometimes while driving. This circulates liquid coolant through the charger/DC-DC converter, motor inverter, and finally the motor.
https://www.youtube.com/watch?v=b-JwaR4GIlE

There is a coolant reservoir under the front hood. This is for the coolant-based cabin heater. This is the reason it takes the heater a minute or two before providing heat. It has to heat up the coolant loop.

There is also a coolant reservoir under the rear motor cover in the hatch. This is the coolant loop for the charger/DC-DC converter, motor drive inverter, and the motor itself. This circulates coolant to a small radiator in the front of the i-MiEV. On hot days, the fan up front may come on. I believe it was mentioned earlier in this thread.

The battery itself is air-cooled only. Active cooling only takes place during quick charging. If your i-MiEV has either the cold weather package or quick charge package (premium package on SE), you have the ductwork going to the battery pack and you'll hear the fan on plugin. There is an easy mod to bypass the car's systems and either heat or cool the battery while driving. I'll post the thread link here unless someone beats me to it.