Radiator Cooling

[Phximiev]

This is an issue that I raised in the passive cooling topic last summer. As the temperature reached 113 or so yesterday and is predicted to be 115 to 117 today, this topic becomes pertinent again.

When you run the AC full bore, which is fine, then you get home or park and turn the AC off (but not the car), the "fan" in the front runs full bore from a minute or so (when the temp is just over 100) to 15 minutes+ or so (when the temp is 115+).

I used to wait for the fan to stop which indicated to me that things had cooled off enough to turn off the car. Yesterday, when the temp was 113, I tried a novel solution, that of spraying water on the radiator. This worked quite well and the fan turned off in a minute or so.

I tried it again this morning and the cooling effect worked as expected.

The question then is whether there is a way to increase the cooling effectiveness of the radiator rather than using a sprayer?

 

[Phximiev]

Hmm, surfed around and found these:

http://10engines.blogspot.com/2009/05/radiator-water-bag.html

I may be dating myself, but many moons ago, early 1960s, I went to a camp outside of Thoreau, NM. When traveling in the truck, the counselors used to hang these 'water' bags in front of the radiator to cool the radiator some. It worked.

Something to do with the flax fiber that, when soaked, would slowly leak, evaporate and cool.

http://wildcanvas-outdoor.com/flax-canvas-water-bag/

Perhaps a 'water' bag for the 'Miev?

 

[Don]

Those desert water bags cool the water in the bag via the evaporative process . . . . not the radiator they're hanging in front of. They used to be common sights in the southwest 75 or 80 years ago

I would *think* that in very hot climates if something on the iMiEV needed cooling after you shut it off, Mitsu would have programmed it to run the fan for as long as necessary . . . . with the car shut off

Don

 

[Phximiev]

I would agree, but for the fact that if you turn the 'Miev off immediately and the temperature shown is above 100 or so, then turn the 'Miev back on, the fans start up, which tells me that whatever it is that is being cooled hasn't completely cooled. This is what started me on this kick in the first place.

The fans do not run below 100 or so indicating that below a certain temperature, no extra cooling is needed at all.

This afternoon, the temp was 117 on the dial, hotter on the road; the AC on full blast. Once home, I turned the AC off and sprayed the radiator and the temperature dropped to 97. However, the fans continued to run this time suggesting that something else was still hot, leading to the following questions:

What all does the front radiator cool?
What else is causing the fan (or something else) to continue to cool?

As an after-thought, I also opened up the back and listened to the engine. Presumably the engine coolant was still running from the gurgling sound. I also noticed rust back there below the top components and on the axles. Anyone else seen rust in the back?

 

[mdbuilder]

Is there a radiator?

Thought it was just an a/c condensor. Suppose I could look, LOL .

 

[Phximiev]

Maybe it is?

 

[PV1]

There is a radiator and an A/C condenser. The radiator is there for cooling the antifreeze loop for the charger, drive inverter (MCU) and drive motor.

I'll have to check the technical information manual, but I believe the fan is temperature controlled based on the condenser temperature. My fan only seems to run at high speed when not moving. There have been several times where OVMS reports motor temperatures above 130 F and the fan doesn't run.

The car may be getting confused by the extreme outside temperature.

 

[Phximiev]

Perhaps so, but its hot again today (113), so when I got home, I just sprayed mist which dropped the temp and the fan stopped in about 5 minutes.

I did get asked by an elderly lady about the 'Miev while out, she was quite enthused (almost as much as us) about the car and thought her family was going to buy a Bolt later in the year.

 

[ed5000]

Phximiev, in your hot, dry climate it would be neat to install a mister in front of your AC condensed coil and the system "radiator". That would give you an extra, maybe 25% in cooling capacity (or more). The only problem is you would want to use a good quality water like distilled water to avoid mineral build up and you would have to make sure everything under there is water tight (like the cooling fan) but it would be a neat experiment.a

 

[PV1]

...and you would have to make sure everything under there is water tight (like the cooling fan) but it would be a neat experiment.a

I would hope that everything already is. These cars are used in rainy weather, so there would be a good deal of water spray coming in through the grille (especially with the rain I drove through yesterday). Mitsubishi even has a video of an i-MiEV driving through water that's up to the bottoms of the doors.

Distilled water would be a must for a mister. If you have a reverse osmosis system in your house, the water from one of those is suitable, as well.

 

[Phximiev]

A mister is a good idea; any idea where I can get one?

I still think that a water bag, perhaps a custom one with holes, would also be a good idea.

But I am certainly open to ideas?

It's already hot again today.

 

[PV1]

A bag would get you a bit of cooling, but only until the water in the bag comes up to ambient temperature. To get the full benefit of water cooling the radiator, you need evaporative cooling, which means water directly on the coils evaporating into ambient air.

The thing is, with your outside temperatures, how hot is the battery pack :? ? I spent two days straight with AC going into my pack when it got into the 90's here. I could only imagine 100+ F.

I am unable to find any specifics on when the fan is supposed to run. I have both the service manual and the technical information manual.

 

[jray3]

I'll second a mister of distilled/deionized water on the condenser/radiator. Using a water mist fogger inside the car may work in a dry climate like Phoenix, with continued ventilation rather than much recirculation. In humid areas, a swamp cooler just makes things muggy.
The i-Miev air conditioning is much more effective than many gassers that I've driven. I wonder if it was oversized due to pack cooling during DCFC?

 

[Phximiev]

Ok, good considerations, but any suggestions as to where can I get a mister?

 

[Aerowhatt]

Ok, good considerations, but any suggestions as to where can I get a mister?

I wouldn't put a mister on it. It's not as hot as Phx here but it is hot and dry. The AC condenser coil is in front, of part (most) of the motor and electronics cooling radiator. So with the AC high on you get a stacked heat challenge. The radiator/AC condenser fan will run as needed. You will find that if you turn the AC off (pushing AC button in the center of the fan speed button) about two miles from your destination. The cabin fan stays on and blows cold air from the cold evaporator coils. The system will be significantly cooler when parking if you use this strategy. Spraying hot parts with water runs the risk of causing system leaks from repeatedly cold shocking the coils.

If the system were overheating you would get error/warning lights. It's working within specs and using the strategy above will save some power and cool the system off better before letting it sit, without causing stress to the system by cold shocking cooling coils.

Aerowhatt

 

[Phximiev]

Good advice, I'll try it.

 

[siai47]

Not that it hurts anything but you would be surprised how much heat is generated in the drive system during recharging from the internal charger. The motor which is in the cooling loop and also electrically part of the charging circuit gets quite warm. The coolant pump runs for several seconds and then switches off for a minute or so. This cycle changes (more pump time) as the system gets hotter. However, I have never had the cooling fan operate during charging so the heat in the system was not effectively being removed by the radiator. I used to place a small fan in front of the radiator when charging on hot days to blow air over the radiator and under the car. That really dropped the temperature of the motor, inverter and charger.

 

[PV1]

Never had the fan run on normal charge, either. The service manual does state that the fan could run on low during normal charge if necessary.

For fan operation while driving, mine's only ever run with the A/C while not moving, though I don't see outside temperatures over 95 F. Invariably, the coolant pump always seem to kick on when the car is put in Park. Bombing around town gets the system quite warm, but I still don't hear the fan run.

A mister would help with temperatures, but it doesn't seem that you're hitting the high temperature triggers. Overall, the design is pretty good, but I fail to see the reasoning why the A/C coil is in front of the radiator. It seems to me that this setup would reduce the cooling capability when the A/C is on, and unnecessarily heat the cooling system under certain circumstances. ICE vehicle I could understand as the hot radiator makes the A/C ineffective, but the i-MiEV's electric drive doesn't make nearly that much heat.

 

[Aerowhatt]

Overall, the design is pretty good, but I fail to see the reasoning why the A/C coil is in front of the radiator. It seems to me that this setup would reduce the cooling capability when the A/C is on, and unnecessarily heat the cooling system under certain circumstances. ICE vehicle I could understand as the hot radiator makes the A/C ineffective, but the i-MiEV's electric drive doesn't make nearly that much heat.

I agree it doesn't make sense for the iMiev. Most likely a case of doing as has been done without excessive thought about how different the system is from an ICE. Ideally the condenser coil and radiator would have independent airflows and fans. Which in the iMievs case could have been done.

Aerowhatt

 

[Phximiev]

Ok, tried the advice posted above. It didn't work in the 110 degree heat. The car heated up so fast that kids and wifey started to complain and despite gutting it out 'til we parked, the fan still ran for another 5-10 minutes in the parking garage in Scottsdale. Family left me sitting there as they were bored with the experiment.

I am still curious as to just why this is happening and perhaps will trot up to Mark Mitsubishi to pose the question to them.