Supplemental cooling for the charger.

[DkubusEV]

The box has a nichicon part number, and looking thru their website i found they take credit for the miev OBC. In fact they claim that it worked so well for Mitsubishi that Nissan converted over to using their design in the Leaf.

Here is a page from a product brochure:

So i would say that nichicon is to blame if there are any thermal issues. Wonder if we could buy them direct without getting middle-manned by Mits?

Very cool info

anyone ever get any information on removing the top speed limiter or the torque limiting that seems to occur? "re map" the MCU??
the Pikes Peak ImiEv Evolution apparently ran 3 imiev motors and they were all boosted up to 80kW and higher RPM...

my project isn't "normal" so more power for temporary bursts would be great.

 

[kiev]

A web search came back with a story that nichicon agreed to pay $42M to settle a USA Dept of Justice case that accused them of price fixing electrolytic capacitors. Later reports indicated that many more companies were included in this lawsuit. So it may be that there is not much e-cap support in the USA anymore...

 

[kiev]

Curiousity killed the cat.

Here is before charging started. The residual heat from driving several hours earlier still shows up in the coolant tube near the top of the picture.

About 30 minutes after start of charging with the cover in place:

and with the cover open:

About an hour after start:

under the cover:

Coolant line to the MCU:

Left the cover open for the evening charge session:

Be Thirsty (and Careful) My Friends,

 

[coulomb]

Curiousity killed the cat.

Nah, fascinating stuff.

I'm curious (am I in danger? ) about the hot rectangles here:

Are these merely because the cover is thinner at those points? I can't see any internal structures that would correspond to the hot rectangles. Unless the blue rectangle is the waffle plate™ showing through, but it seems unlikely to remain that sharp.

The mains cables really have fire in them, huh? At least from these shots with the cover on. It certainly seems that it's the magnetics that get the hottest. Of course, they can stand it, but they transfer a lot of their heat to the capacitors and semiconductors, which will age. Edit: however, the capacitors, at least the tops of them, seem quite cool compared to the furnace elsewhere.

 

[kiev]

Those rectangles are silver/aluminum labels on the cover which can reflect and give false readings. i probably should have covered them with black tape.

i did put black electrical tape on the caps which is supposed to allow a temperature measurement rather than a false reflection of the aluminum tops. Compare the before and after with cover off to see the caps and tape.

The big blue rectangle on the top is the external EMI filter bolted to the lid. It too has an aluminum label, as does the MCU located to the right of the OBC.


There is already a small ~1/2" vent hole in the front left side of the charger--it has a plastic (filter?) plug. So maybe another hole could be added near the right rear corner by the inductor to blow air in, and remove the plug to let it flow out.

 

[jray3]

Jay if I'm understanding your description of the motor bay hatch insulation on your 2012 it actually touches the top of the charger unit? The 2014 hatch definitely has some air space between the hatch sound insulation and the top of the charger. I would guess somewhere around 3/4 of an inch. The insulation is molded on the bottom side to provide this space.
Aerowhatt

Aero, I mistook the molded relief space to be in contact, but there's no rub marks or a dust shadow to confirm this, so yes- no contact.

How about some teaser photos of your blower prototyping? Wife's getting tired of me opening the motor bay hatch and cracking all windows during a recharge.. :roll:

 

[JoeS]

.. Wife's getting tired of me opening the motor bay hatch and cracking all windows during a recharge.. :roll:

Good to know there's more than one paranoid person worried about this issue ... need a quick-release for that motor bay cover and it's a PIA to move my carpet and spare tires out of the way... :roll: For now, at home I just have the fan blasting upwards and have abandoned the fan in front of the radiator after running over it (one of the drawbacks of backing into the garage)

 

[Don]

Yup - Paranoid!

I've been recharging only overnight now when it's cooler and since time is no longer of the essence at all I'm only using the OE 8 amp L1 EVSE. I think the big 435 cfm blower I have does a good job of moving air around and probably will make L2 charging safe, but it's a pain to stuff that under the back of the car every time I want to charge

Don

 

[Aerowhatt]

I don't think it's paranoia. Given the internal temps that Kiev has posted it's a valid concern.

I've gotten the blower airflow optimized and my wife is out of town this weekend. so I should get the bracket jig together and a few brackets made (she calls things like this "goofing off" so perfect timing ). Kiev has been generous enough to agree to taking new readings with this kit in place on his iMiev. I'm waiting to get delivery on the thermal switches to make them automatic. Currently, I have turned a switch up in the shop (wrong type for the environment, but right temperature rating) and wired the prototype on my car up with it. Really, really like hearing it kick in and do it's valuable work throughout the whole charge cycle. I haven't caught the end of the charge cycle yet so I don't know how long after the charge ends that the unit continues to run. I'm not worried about that though, only pulling 0.7 amps it doesn't put a dent in the 12V battery while getting cooled down enough to turn itself off.

Aerowhatt

 

[Aerowhatt]

So a bit of an update. I have had the updated bracket in the car most of the week and working in "automatic" mode. The thermal switches that I ordered for this project are set to arrive in tomorrows mail.

So far I'm pretty happy with the function (these are all L2 charges). With the temporary thermal switch, it comes on in the first 30 minutes of charging starting. Only about 5 minutes if it has just been driven with the AC cranking. Then at the other end of the charge it lingers, running anywhere from 20 minutes to 70 minutes after the charge ends before turning off. Definitely making a significant difference in the overall temperature of the unit during charging. Really looking forward to Kiev's imaging comparison for a more quantitative read on internal component temperatures.

View attachment VGV7iKdbSc+6z561KUrobA_thumb_178b.jpg

You can just see the blower under the bracket. It is held in place by the channel over the lip of the "hood" opening. And a single bolt in the existing threaded hole on the charger case.

 

[PV1]

Has anyone done temperature measurements on a reduced current level 2 charge? Does charging at 12 or 10 amps reduce the generated heat in the charger?

 

[Aerowhatt]

Has anyone done temperature measurements on a reduced current level 2 charge? Does charging at 12 or 10 amps reduce the generated heat in the charger?

As designed the OEM cooling system delivered the following results.

Under L-2 the case temperature peaked at 56F above ambient temp.
Under L-1 (12 amp) the case temperature peaked at 48F above ambient temp.
So charging L-1 only delivered a ~15% decrease in charger temperature rise.

I didn't check the temps at 8 amps L1 since I don't consider it a useful charge rate for our needs. Plus the high percentage of power going to overhead "vampire loads" rubs me the wrong way. Presumably 8 amp L-1 would run some cooler than 12 amp. I wonder though if that matters much though since most components are rated in "Mean TIME between failures". And L-1 runs the unit much longer than L-2 for each recharge?? I'm not sure that most people have the ability to do a lowered amperage L-2 charge but it seems as though the results would be similar to L-1.

Aerowhatt

 

[JoeS]

...You can just see the blower under the bracket. It is held in place by the channel over the lip of the "hood" opening. And a single bolt in the existing threaded hole on the charger case.

Aerowhatt, looks like a nice clean install. Speaking of clean, is that compartment merely the result of vacuuming?

 

[kiev]

The 2014 OBC looks different than the 2012--is there a small EMI filter box bolted to the lid toward the rear of the car?

If you get a chance to open the cover and snap a picture it would be interesting to compare the interior.

 

[Aerowhatt]

Aerowhatt, looks like a nice clean install. Speaking of clean, is that compartment merely the result of vacuuming?

Thanks JoeS, I think the brackets still look handmade . . . likely because they are handmade. It's a nice sturdy fit though.

As for the cleanliness under the hood. I've always done all of my own mechanic work on vehicles. They are just a lot easier and more pleasant to work on if kept reasonably clean. I use a low pressure compressed air stream to blow out of the bottom everything that that a vacuum with a soft brush can't reach. Then finish off with a slightly damp cloth or paper towel to wipe the obvious culprits. It only takes about 15 minutes per car and once every 6 months is plenty often enough in this climate.

Aerowhatt

 

[jray3]

Hey Aerowhatt, could you post a materials list and perhaps a drawing of your fan bracket? I'd like to get that cooling mod made while the weather is still so hot.

 

[Gorfllub]

Here is a thought to improve cooling performance.

Use an additive such as water wetter.

It definitely increases heat transfer both into and out of the coolant.

It's inexpensive and requires no setting up of any fans or anything.

Its not going to a be a life changing improvement, but it will indeed be an improvement.

I am definitely going to do it now that I think of it.

 

[Don]

Great idea!!

They claim an improvement of as much as 20 degrees, which in our case is a pretty significant improvement. One bottle should do 2 or 3 cars. I think I'll be doing it also. Every little bit helps!

https://www.redlineoil.com/waterwetter

Don

 

[Aerowhatt]

Great idea!!

They claim an improvement of as much as 20 degrees, which in our case is a pretty significant improvement. One bottle should do 2 or 3 cars. I think I'll be doing it also. Every little bit helps!

https://www.redlineoil.com/waterwetter

Don

"Reduces or eliminates bubbles or vapor barrier that form on hot metal surfaces to reduce coolant temperatures by up to 20°"


Yeah pretty unlikely that this will make a difference at the coolant temps on the iMiev. More geared toward the near vaporization temps found in ICE engine cylinder heads.

Aerowhatt

 

[Aerowhatt]

Hey Aerowhatt, could you post a materials list and perhaps a drawing of your fan bracket? I'd like to get that cooling mod made while the weather is still so hot.

Sure I will do that as soon as I can. Some life complications at present unfortunately. What would be best perhaps a template for the bracket? The blower used is critical a lesser one will not make the cut. I just got those temp switches in yesterdays mail. They came all the way from China which explains why they took so long. How the heck do you sell something shipped for $11. Ship it half way around the world and make any money?? Hope they aren't crap! Testing tomorrow or Sunday hopefully.

Aerowhatt