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Re: Supplemental cooling for the charger.

Fri Aug 10, 2018 8:07 pm

kiev wrote: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.

I'm not sure where you are referring to exactly. I'm not up for opening the OBC cover while it's still under warranty. Can you discern the difference from a good picture of the outside of the cover?

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Re: Supplemental cooling for the charger.

Mon Aug 13, 2018 10:03 am

Aerowhatt wrote:
jray3 wrote: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?

Yes, a template to trace sounds great, but I'd be good to go with a dimensioned drawing. I get your meaning about lesser fans- I had a couple die from minor mist in the Karmann Eclectric motor bay..
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Re: Supplemental cooling for the charger.

Tue Aug 21, 2018 12:01 pm

Another thought. Since the factory liquid cooling loop doesn't seem to be absorbing much of the heat generated by the charger, could it be that the cooling system needs to be flushed and new coolant installed? Chevy mandates this every 5 years for their Volts and our 2012's are probably all beyond the 5 year point by now. I'm just guessing, but I would think a good cooling system flush, a purge with clean water and a refill with the recommended anti-freeze could very well improve the heat transfer by 50% or more - Maybe this is all we really need? We went many years with no reported charger failures and now they seem to be dropping like flies . . . . and we know for sure the cooling system isn't functioning very well because the inlet and outlet coolant temperatures are nearly the same

I do know any heat exchanger with scum built up on the inside of the tubes would exhibit greatly reduced heat transfer. If we got it back working at OEM efficiency, maybe the problem is solved. What do you think??

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Re: Supplemental cooling for the charger.

Wed Aug 22, 2018 8:30 am

Don, yet another possibility, although IIRC it's the non-heat-sinked components that are getting hot that are the concern.

According to the i-MiEV Owner's Manual, the car uses "Dia Queen Super Long Life Coolant Premium", or an equivalent "high quality ethylene glycol based non-silicate, non-amine, non-nitrate, and non-borate coolant with long life hybrid organic acid technology". I've used the manual maintenance schedule to point out that only at 240 months (20 years!) does the manual specify to change the motor coolant and heater fluid.

Our i-MiEV cooling system does not undergo the dramatic temperature excursions to which an ICE vehicle is subjected, and thus perhaps is not subject to the same issues. If anyone does change the fluid, it would be nice if you could do a before/after thermal measurement.
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Re: Supplemental cooling for the charger.

Fri Sep 07, 2018 2:33 pm

Finally get a chance to poke around the on board charger/DCDC. Boy that thing can really get warm. It seems that one of the problem is that there is no way for the hot air to circulate, it gets all pooled into that canopy. Aerowhatt's fan is great but I would add a hose to duct cooler air lower down. First we would get better heat transfer with a wider delta-T, and there would be some convection a la ceiling fan affect.

For now, I just propped open the canopy lid when charging L2. The convection of the warmer air will be welcomed into the cabin as the weather is getting cooler here.

Another lazy person option for over night charging is to use a timer to stop/re-start charge every hour for half an hour or so.

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Re: Supplemental cooling for the charger.

Fri Sep 07, 2018 9:02 pm

pbui19 wrote: Another lazy person option for over night charging is to use a timer to stop/re-start charge every hour for half an hour or so.

If you go this route, I'd recommend not stopping the charging by just killing the AC input. PFC stages don't like interrupted AC, and the relay or contactor won't last long. If possible, effectively operate the J1772 switch, so the on board electronics does an electronic shut-down. That way, the cooling pump still operates while the charrger is resting, for extra cooling. Though you could kill the AC as long as it happens a half second or more after the J1772 switch is operated, to save power.

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Re: Supplemental cooling for the charger.

Mon Sep 17, 2018 3:58 pm

just found this thread... I'm so glad. I live in new orleans and often charge in the daytime, where sun shines down through my back window! I'll start charging at night.

i like the blower system, i would love to buy a kit if it becomes commercial or try to make my own.

so the fan power is pulled from a 12v always on source or 12v on during charging only?

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Re: Supplemental cooling for the charger.

Tue Sep 18, 2018 1:31 pm

ok i ordered the fan. Instead of a temp activated switch, is there a 12v source nearby that is on when the charger is on? that would do for me since its pretty hot here for a lot of the year and the fan is only a few watts.

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