Don
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Re: Supplemental cooling for the charger.

Thu Jul 19, 2018 3:40 pm

There is an OEM fan on the radiator at the front of the car - Any thoughts on just making a mod to use that fan?

Many ICE cars have 12 volt cooling fans behind the radiator which are energized using a thermal switch on the radiator tank - When it gets hot enough, the fan comes on for long enough to cool things down until the coolant switch de-energizes. Something like this shouldn't be too hard to fabricate. Hook power to the thermal switch 24/7 and just let it do it's thing . . . . the fan would automatically run anytime it's needed

If the charger is water cooled, I like the idea of making that work, rather than blowing air on it

Don
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Aerowhatt
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Re: Supplemental cooling for the charger.

Thu Jul 19, 2018 5:47 pm

Don wrote:There is an OEM fan on the radiator at the front of the car - Any thoughts on just making a mod to use that fan?

Many ICE cars have 12 volt cooling fans behind the radiator which are energized using a thermal switch on the radiator tank - When it gets hot enough, the fan comes on for long enough to cool things down until the coolant switch de-energizes. Something like this shouldn't be too hard to fabricate. Hook power to the thermal switch 24/7 and just let it do it's thing . . . . the fan would automatically run anytime it's needed

If the charger is water cooled, I like the idea of making that work, rather than blowing air on it

Don


So far my data clearly shows that the fluid cooling of the charger is not designed that well. Sure it helps to blow air through the radiator and/or run the circulating pump full time too while charging. Even with these steps the charger still runs hot. Cooling the charger directly with air actually brings the coolant temperature down more than blowing air through the radiator does. Are you drawing some other conclusion from those numbers? When the car is in ready mode the radiator fan works just as it does on an ICE car as you described. However if the design of the chargers fluid cooling is less than adequate (which the data shows) you would need to refrigerate that fluid to do a good job of cooling the charger down.

Aerowhatt
2014 cool silver ES, acquired new 4/2015 (42.7ah at ~26K miles)
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Don
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Re: Supplemental cooling for the charger.

Thu Jul 19, 2018 7:49 pm

There must be much more heat generated when driving the car, cooling the motor and the inverter - I can't believe the cooling system that handles that cannot handle the charger alone. In your tests, do you think you were moving as much air through the radiator as the stock cooling fan would? If the water cooling loop can't adequately cool the charger alone, then Mitsu really missed the boat . . . . which is a tad hard to believe

Don
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jray3
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Re: Supplemental cooling for the charger.

Thu Jul 19, 2018 10:11 pm

While driving, the waste heat loads should be higher, yes, but there is more than just the radiator fan at work. The turbulent air in our motor bay has to provide some cooling as well, compared to the hot stagnant air during a recharge. I'm just glad I never got around to making that rear belly pan for aerodynamic improvement!
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Don
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Re: Supplemental cooling for the charger.

Fri Jul 20, 2018 11:41 am

For now - Until we find a way to energize the OE radiator fan - I'm using this blower on medium speed placed in front of the car. It forces at least 90% of it's air into the radiator with almost none hitting the bumper cover

https://www.samsclub.com/sams/pivoting- ... roduct_1_5

That's 435 cfm compared to the 50 cfm that Aerowhatt found decreased the fluid temperature by 9 degrees. Lots more air should provide lots more cooling. I still think some sort of switch to energize the OE fan (as siai47 suggested) is the ultimate answer. I think it's position mounted on the radiator might be even more efficient than blowing air in from the front

Edit: After charging L2 @ 12 amps for an hour, with the car sitting outside in the 95 degree afternoon sun (pretty much a worst case scenario) the inverter isn't hot - I don't have a non-contact thermometer, but I can put my hand on it anywhere comfortably and keep it on there for as long as I care to. It's for sure warm (to be expected) but it's not hot. The DC to DC converter on the other hand is quite hot . . . . too hot to leave my hand on for very long. Since they made no effort to cool it, and it sits atop the inverter, I hope it was designed to run hot. The coolant pump is cycling normally and only stays running for a minute or so when it does kick on, so I think the car's cooling system is probably operating as it should - I think it's pretty apparent that it needs a radiator fan though

Edit 2: Checked it again after another hour. The inverter does feel a little warmer to my hand. The coolant pump is kicking on after about a minute and running for about 30 seconds. By far, the coolest thing back there is the coolant hoses - A little warmer leaving the inverter than on the incoming side, but considering it's 95 degrees outside, the hoses don't feel much warmer than that to me - Much cooler than the inverter itself. If we don't come up with a better solution, I'll be using this fan for all my summertime L2 charging

Don
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JoeS
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Re: Supplemental cooling for the charger.

Fri Jul 20, 2018 11:48 am

So, yesterday was a busy day with a non-stop 65+mile round trip to SFO and by mid-afternoon when I returned home I had run the car down to two bars so I just left it sitting there to cool off, with CaniOn showing the battery pack at around 31°C (88°F). Plugged into L1 at around 10pm. Stuck a 6" fan in front of the radiator and placed an 8" fan underneath the left rear of the car, facing upward and left everything on all night long. I just wanted to move air and not let it stagnate, rather than force-cool. By 7:30 this morning (15 bars) here were my readings with an uncalibrated infrared non-contact thermometer -

Car chassis (we cool off nicely at night): 66°F (18.9°C)
Charger chassis top front right side: 95°F (35°C)
Charger chassis top front left side: 87°F (30.5°C)
Charger chassis top rear right side: 90°F (32.2°C)
Charger chassis top rear left side: 87°F (30.5°C)
EMI Filter case: 95°F (35°C) [Edit: had incorrectly called this the BMU and doghouse :oops: ]
Fluid hose (left side of Charger: 77°F (25°C)
Motor drive inverter chassis: 74°F (23.3°C)

Even with the air circulating (but not blowing cooling air directly onto the charger), this has resulted in a charger chassis temperature that is 29°F (16°C) above ambient, pretty-well corroborating Aerowhatt's readings. (Sigh) :geek:
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Aerowhatt
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Re: Supplemental cooling for the charger.

Fri Jul 20, 2018 5:58 pm

Don wrote:There must be much more heat generated when driving the car, cooling the motor and the inverter - I can't believe the cooling system that handles that cannot handle the charger alone. In your tests, do you think you were moving as much air through the radiator as the stock cooling fan would? If the water cooling loop can't adequately cool the charger alone, then Mitsu really missed the boat . . . . which is a tad hard to believe

Don


It's not the cooling system of the car. It is well engineered and delivers coolant back to the parts needing cooled at just a couple of degrees above ambient temperature and only 11F or 12F above ambient with the AC cranking full bore while being driven. So the cars cooling system is awesome. The problem arises inside the charger (in the design of the liquid cooling of the charger). The coolant coming out of the charger(while charging) is only ~ 1F hotter than the coolant going into it. There is not good transfer of heat from the hot components of the charger to the coolant loop. If you run coolant through a device that is 56F above ambient on it's case it should come out a lot more than 1F hotter than it went in. Remember Jray's original observation that the coolant outlet hose of the charger was warm but not hot, while the case of the charger would burn you? I measured mine's inlet hose and outlet hose in real time with an infrared thermometer. The heat transfer to the coolant in that charger is criminally pathetic.

Since the charger design does not allow for good transmission of the heat to the coolant it doesn't matter very much how much air is put through the radiator. Most of the heat from the charger never makes it to the radiator to be removed. Most of it is forced to migrate to the aluminum case. Ergo the best cooling (without redesigning the charger) is by cooling the case . . . as the data shows.

Aerowhatt
2014 cool silver ES, acquired new 4/2015 (42.7ah at ~26K miles)
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Re: Supplemental cooling for the charger.

Fri Jul 20, 2018 6:11 pm

JoeS wrote:BMU case (sits on top of Charger): 95°F (35°C)


Do you have a picture of the charger setup in the 2012? It sounds different than the 2014.

Aerowhatt
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JoeS
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Re: Supplemental cooling for the charger.

Sat Jul 21, 2018 5:10 am

Aerowhatt wrote:
JoeS wrote:BMU case (sits on top of Charger): 95°F (35°C)
Do you have a picture of the charger setup in the 2012? It sounds different than the 2014.t
Dunno what possessed me to call it the BMU. :oops: What I was referring to we've been calling the doghouse portion of the OBC/dcdc. Edit: Bumbling along, as kiev properly pointed out, it's the top of the EMI filter. :oops: :oops: Corrected my post.
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kiev
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Re: Supplemental cooling for the charger.

Sat Jul 21, 2018 7:43 am

During the course of dismantling jay's charger i discovered that the 'clear' plastic sleeving and black heat shrink tubing on the inductor and transformer wiring had somewhat melted and fused together. i don't know at what temperature that would occur, but it is likely greater than 360 F. i've never seen heat shrink melt while using a heat gun during application and it is rated at 360F max. i posted some pictures of the internal aluminum heat sink for the soldered board in the troubleshooting thread.

i connected to level 2 for charging this morning and measured some temperatures inside the box.

started at 8am, everything at ambient, 76F

checked at 9 am, ambient at 80F; 10am, amb at 83
water pipes
MCU 88; 94
OBC 89; 94
EMI filter top (joe's doghouse), 102; 114
side of obc case, 96; 98
large cap, 127; 144
large inductor rear, 208; 194
transformer rear, 195; 184
trans front, 165; 210
small inductor front, 174; 212
top board surge supp potting, 158; 165

So it's gettin all Hot up in Herre
Last edited by kiev on Sat Jul 21, 2018 12:37 pm, edited 1 time in total.
kiev = kenny's innovative electric vehicle

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