Passive cooling ?

[Phximiev]

107 or so and pretty much duplicated the previous scenario. Ran the AC througout the trip, parked, turned off the AC fan and AC, and thereafter the other fan continued to run for several minutes. After the other fan stopped, the pump noise continued until I shut the car off.

One difference I did note (that I didn't note before) is that when the other fan was running (and again after I turned the AC off), it seemed/sounded like the AC was still working, but no air came out the vents.

I will listen tonight for the fan sound when I plug in.

 

[Phximiev]

Ok, I sat inside the iMiev and listened to the fan sound while my wife plugged in our TurboCord. I will compare this to the other fan sound tomorrow, but at this point it sounds the same.

 

[Phximiev]

2016 iMiev specifications on the Main Drive Battery:

http://www.mitsubishicars.com/imiev/specifications

If you open the Main Drive Battery topic, it says as to Cooling System: "Forced air ventilation".

Anybody have any idea what this means?

 

[PV1]

Forced air is air blown into the battery by fans. The cooling system does double duty by forcing air in with the cabin HVAC system and drawing air through the battery with the fan in the pack.

Based on your observations, the i-MiEV does seem to cool the pack when outside temperatures are above 100 or 105 F while driving.

There are three fans in the i-MiEV.
1. The radiator fan in the front which comes on with the AC while stationary, though it will keep running if needed while moving.
2. The cabin fan forces air through the vents and into the battery when the damper is flipped (controlled by the servo in the driver's footwell).
3. The battery fan in the battery pack draws air through the pack, assisting the cabin fan when cooling or heating the pack. This fan is heard every time the car is plugged into level 1 or level 2 charging stations, and while quick charging below 67% and 30 C pack temps.

I can post sounds of all three fans if you'd like. I actually have uploaded the battery fan already:
https://youtu.be/7p30lMFfVPI

and the coolant pump for the motor, inverter, and charger:
https://youtu.be/b-JwaR4GIlE

 

[Phximiev]

Ok, but is it the same in the 2016 model? I don't seem to recall seeing that same statement when I looked at any of the prior models.

And despite my observations, I would still really like to confirm (by Canion or some other test?) that when the temp gets over 100 the fan that I am hearing is actually cooling the battery. I am not quite sure how to do that.

 

[Aerowhatt]

Ok, but is it the same in the 2016 model? I don't seem to recall seeing that same statement when I looked at any of the prior models.

And despite my observations, I would still really like to confirm (by Canion or some other test?) that when the temp gets over 100 the fan that I am hearing is actually cooling the battery. I am not quite sure how to do that.

I have seen nothing to suggest that there is any difference between the 2014 and 2016 systems.

When you get home or to your destination in these very high temperatures.

1. Leave the key alone in ready mode
2. Put on the parking brake and put the Selector in PARK.
3. Exit the vehicle and move around towards the back of the car. There is only one fan back there (the battery case exhaust fan) Wait a few minutes as it may be cycling. As PV1 said it is the same fan sound you hear when connecting EVSE power to the car for charging. You should easily be able to tell if you are hearing the rear fan or the one(s) up front from outside of the car. Much harder to discern from inside the car!

It's hitting 99F and 100F here and I have been logging data and have been monitoring battery case temperature and the operation of the battery exhaust fan. So far I don't have definitive results but should in a couple of weeks or so. One "problem" that I have is that the battery always starts out at 76F to 80F because my garage is cooled (no I don't use extra electricity to cool the garage) Cooling it (the way that I do) actually reduces cooling costs for the home. But that part is off topic and a bit complicated.

Plus, I'm also logging data during regular driving of pack temperature rise rates with some of the cabin AC routed through the pack as some others have done in this thread. So my focus is split which makes drawing conclusions for both take longer.

My feeling is this. The manufacturers want to put in place remedies to keep you from destroying your battery pack. These are not necessarily the same as remedies to take really, really good care of it. My goal here is modify the parameters of "safe" battery temperatures that the car tries to maintain to a more conservative set which will not only prevent damage but will promote maximum longevity.

Aerowhatt

 

[JoeS]

I've extracted the following from a post that Malm made on another thread. He has evidently modified his ductwork and is showing that after extensive driving in 25C (77degF) ambient with aircon running that his battery pack is happily sitting at 18.6C (65.5degF).

...Did you saw the temperature, 18,6 ºC? That was a trip in a summer day, 25º C outside.
More at http://www.nissanleafpt.com/viewtopic.php?f=32&t=1556&start=1960

What you do is copy that URL and then paste it directly into Google Translate.

Malm, could you perhaps give a brief description of your ductwork modification?

 

[Malm]

I have difficulties to explain it in English for you, but PV1 did exactly the same thing (if I understood correctly his words):

So PV1 said:
"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 never use the floor vents unless it's really cold out. If outside air is cooler than the battery, I simply run the fan on high, but if I need AC for the cabin, then I'll share it with the battery...at least on these 85-90 F days.

I agree that the i-MiEV is easy to manually cool/heat the pack, but we do have to watch the temps more closely than a liquid cooled pack, though it evidently will engage battery cooling at some point. I believe the Volt normally only cools the pack when charging (account from the driver of the company Volt)."

I only don´t know which one of us made this procedure for the first time, I began to do it in may 2014. And I usually don´t share cold air between the cabin and the battery, the cold air goes all to the battery, if the occupants feel to hot, then the solution is opening the windows. Since may of 2014, the degradation rate of my battery seems to be much lower. I see a big difference (20% loss in range) in the first three years, but can't see any loss in the last 15 months.

Adding to this, the car in the last 15 months stays outside by night, making the batteries colder in the morning, and in some hotter days, simply don't use it. But stills do many miles. Now at 81000 km, no one here did more, I believe.

In Portugal, we that have electric cars (mostly Nissan Leaf), call to the period of time between 2011 and 2013, the crazy years. We didn´t take any care about the temperatures, but then after 2 years, one bar of the Nissan Leafs disappeared (15% loss). Now even my friends that have a Nissan Leaf found ways to cool their batteries, and they do it often. Not as easy as with the I-MiEV, so they have some envy of me in this particular advantage.

No signs of cell failure until now, all charging to 4,1/4,105 V. Charges to 16 bars. 100% SoC most of the times. Turtle of 9,5% SoC, goes exactly to 0,0% SoC. Well, then it should be as a new one. No, because 100% SoC in my car is now significantly less energy then when it was new.

 

[JoeS]

Malm, thank you for confirming that your modification is the one described on this thread.

...I only don´t know which one of us made this procedure for the first time, I began to do it in may 2014...

siai47 described the mod in his 14 June 2013 post earlier in this thread: http://myimiev.com/forum/viewtopic.php?p=10701#p10701
jaraczs posted photos of his October 2012 exploration into the ducting, also earlier in this thread: http://myimiev.com/forum/viewtopic.php?p=10727#p10727

About that timeframe was a big AHA moment for us, with the realization that the i-MiEV has two different battery cooling schemes.

 

[Malm]

Yes, you are right JoeS, siai47 described the procedure for the first time. Only today I understood how he did it . Because I did it in a slightly different way (without loosen the screws), but the result is exactly the same. Not broken anything, like him .

Like someone said, there are many ways to get to Rome.

 

[JoeS]

... I did it in a slightly different way (without loosen the screws), but the result is exactly the same. Not broken anything, like him . Like someone said, there are many ways to get to Rome.

Malm, for those of us who still have not done the mod, have you described what you did somewhere? Pictures? Curious minds want to know...

I'm kinda tending towards a separately-powered switching scheme that Aerowhatt described...

 

[pbui19]

slightly OT:

so if the battery cooling fan only draws air from the cabin during charging, we should not charge with the car parked in the hot sun with the window up then ? the fan would just be sucking in hot air ??

 

[Malm]

... I did it in a slightly different way (without loosen the screws), but the result is exactly the same. Not broken anything, like him . Like someone said, there are many ways to get to Rome.

Malm, for those of us who still have not done the mod, have you described what you did somewhere? Pictures? Curious minds want to know...

I'm kinda tending towards a separately-powered switching scheme that Aerowhatt described...

No. The procedure is very similar to the one described by siai47. I advise to do it as him. I showed to alohart when he came to Portugal last year, usually I show this modification face to face, don't have any pictures or videos of it. If I have a problem in the future, the car will go to Mitsubishi as no modification has ever occurred.

 

[PV1]

slightly OT:

so if the battery cooling fan only draws air from the cabin during charging, we should not charge with the car parked in the hot sun with the window up then ? the fan would just be sucking in hot air ??

If the cooling system runs, it draws air from the fresh air intake. It won't pull air from the cabin. If the battery isn't too warm, only the fan will run, but I think around 30 C battery temps the AC will engage.

If you guys would like, I can post a how-to video on the battery cooling mod. It's very easy to do and 100% reversible.

 

[JoeS]

If you guys would like, I can post a how-to video on the battery cooling mod. It's very easy to do and 100% reversible.

Yes, please, as it will add to the completeness of this thread. Thank you.

 

[Aerowhatt]

I'm kinda tending towards a separately-powered switching scheme that Aerowhatt described...

I'm still looking for that little plug (the match to the one that plugs in to the damper actuator) to make it easier. But it is very non invasive and takes less than 5 seconds to make it look like it never happened (just plug the OEM plug back into the actuator). The first time you turn on the key the actuator closes the battery duct damper as Mitsu intended for the service departments pleasure.

Watching the results on Canion and having high 90's and low 100'sF. for a week recently. I find that I'm unable to actually cool the battery much. But comparing it to not sharing the AC with the pack, there is a big difference in the end of trip temps. In other words keeping it from heating up would be a more accurate description when ambient temps are very high.

Caveat: I have the luxury of starting a hot ambient temperature drive with battery temps around 80F, 26C due to my garage situation. So I'm rolling into 100 degree ambient with 80 degree cells and they are also producing heat as they discharge. So maintaining or almost maintaining starting temp is not bad at all, given the starting parameters.

Another observation of note is that with the cabin blower on high and all the air going to the pack it cools less well than with the fan on medium? weird right? Not really, the battery pack duct is small and long and curvy. With the fan on high the back pressure on it is quite high which makes the blower fight to try and move more air. This beating up of the air actually imparts heat to it. This heat represents wasted electrical power too, since the fan motor is loaded down so much. Thats why, when the battery gets hot enough to worry Mitsu the system pushes AC from one end and pulls from the other end (battery case exhaust blower in the back) simultaneously. The rear exhaust blower lowers the air pressure in the pack helping to pull the AC in from the front. I'm not convinced that we can't fool this rear blower into running when we want it to (still working on that). So if running all the AC to the pack only, use mid blower speed, if sharing with the cabin use a higher blower speed.

Aerowhatt

 

[pbui19]

I removed the two screws and 1 electrical connector per siai47 and everything became obvious. One advantage of going the mechanical route instead of the electrical bypass, is that the damper can be set to partially direct air to cabin and to battery pack.

But I have to make it a point to set it to battery path when using QC, hum, not idiot proof...

 

[Malm]

:lol: I agree, not idiot proof. I forgot once, in a quick charge, to open it. After some minutes I looked to the temperatures and they where 4ºC hotter. If it wasn't Canion, hotter would became. Well, that's what happens with the Nissan Leaf every quick charge.

 

[pbui19]

I have removed the damper controller and mostly set the damper to direct the flow into the battery pack. My thinking is that I can control the flow using the console lower vent setting to meter the flow. Two surprising events happened and I am wondering if any one can confirm:

1. Upon QuickCharge, the AC doesn't turn on as normal ? haven't gotten around to check whether it was due to the electrical disconnect of the servo controller (the servo wasn't in the car). I now carry the servo and a volt meter to determine whether that middle 3rd wire is in fact a signal or some sort. But I haven't the chance to do a QC yet.

2. As temperature approached 98F today so I thought to turn on the AC using the remote to divert some cool air into the pack. But it seems all the cool air was coming out of the upper vents and none to the floor regardless of the damper setting. Without using the remote, AC flow is back to normal; but of course power is from the pack and not from the EVSE.

???

Thanks

 

[PV1]

I've found that the car doesn't always cool the pack when quick charging. If the pack is cool enough (below 30 C I believe), the car will only run the fans until roughly 66%, at which point they will turn off. However, if the pack is warm enough for the AC to run, it will stay running up until QC stops around 80%. Look for the AC light to be on while quick charging. The fans come on before the servo is flipped by the car. I'd test it after work tomorrow, but the quick charger in town here has been derated to 10 kW :evil: . The fans will not run at this charge rate.

The remote Cool option doesn't blow air to the floor. The controls in the car are overridden by the remote and quick charging. HEAT will run the fan on low and push heat to the floor, and Defrost will run the fans on high with heat going to the windshield. It will also activate the rear defroster and heated mirrors (if equipped, included on US 2012's with cold weather/quick charge packages, premium package, and all 2014/2016 models). Also, the remote preconditioning will error out if you try to activate it with the door open .