Active cooling your leaf battery

[minispeed]

Here's what road and track did with the Tesla on the race track

http://www.motortrend.com/news/2013-tes ... -update-4/

Now it didn`t help turn a quicker lap although they didn`t get the warning the second time they did give up the warm up lap too.

It would get expensive to use that much ice every day though. You could stock up on ice packs but you`d have to have a freezer where you park the car and it would be a lot of work.

I think your best bang for you buck is to tint the windows as dark as you can and if the car is a dark colour use a vinyl wrap to turn it (at least the roof) white.

[Andrejun]

I have experience with mineral oil as a coolant, 0 issues with corrosion, 0 electrical issues overall it just works. Only issue is that the oil wicks through any multi strand cables that penetrate the oil/ air layer.

I don't know how much empty volume is in the pack, but density is around 7.5 lbs/ gallon.

Price for medical grad mineral oil is about $15/ gallon.

One thought would be a sump and a dribble over all of the batteries when returned from the radiator. I'm going to guess that a few gallons would be adequate.

[LeftieBiker]

Best of luck with that, and don't forget to post pictures!

[KillaWhat]

I confess I did not read every post on here about this subject.

I’ve got a bunch of engineering degrees, and this subject has come up in my life as well.

Conceptually, with any radiator or heat dissipation system, the BEST theoretical outcome would be cooling to ambient temperature, and that’s a theoretical goal only.

If it's 100F out, then you are not going to cool anything below 100F?

You need to introduce an active cooling process or thermal exchange process, either solid state thermal panels, such as those used in tiny portable 12volt fridges, or an air conditioner compressor system.

Just FYI, there ARE insulating fluids used for direct contact cooling of computer system components.
The CRAY cruciform systems used fluorinert, a 3M product that was used in direct contact with the processors. It’s surprisingly available. Interesting thought.

I guess if it was me, and I HAD to figure out a way to do this, I would “glue” a bunch of Peltier Thermoelectric Cooling/Heating modules directly to the battery housing, remove the under-car covering, and heat-sink the crap out of "hot side" of the modules.

Easy to come by..... here is the E-Bay search.
http://www.ebay.com/sch/i.html?_from=R4 ... e&_sacat=0

Air flow across the heat sinks would improve efficiency obviously.
Insulating the battery housing would help, but then you trap the heat IN when not actively cooling.

IF you stick enough Peltier modules to that battery case, you WILL get a frosty battery housing.

It’s super simple, solid state, no moving parts, no fluids, no pumps….. Maybe heat-sinks with fans?

Good luck

[TomT]

I am SO glad that I don't have to concern myself with such considerations anymore! Now I just charge and drive without worrying about it.

[LKK]

"Just FYI, there ARE insulating fluids used for direct contact cooling of computer system components.
The CRAY cruciform systems used fluorinert, a 3M product that was used in direct contact with the processors. It’s surprisingly available."

I've used this stuff in an old fashioned high voltage, high power transmitter that had to be packaged in a small volume. The fluid was cooled using an external A/C. This stuff is really expensive, if I recall correctly about $90/liter and was much heavier than water, more like latex paint. Worked great fending off anti-ship missiles, not sure if its use in a consumer product like a car would be feasible.

[KillaWhat]

I've used this stuff in an old fashioned high voltage, high power transmitter that had to be packaged in a small volume. The fluid was cooled using an external A/C. This stuff is really expensive, if I recall correctly about $90/liter and was much heavier than water, more like latex paint. Worked great fending off anti-ship missiles, not sure if its use in a consumer product like a car would be feasible.

That's funny- anti-missile applications. Non-reactive gooey armor.
Yes, like most high-end stuff it can be expensive when used and purchased for it's original purpose .

I too am not sure flooding the battery module with liquid is the best way to go, but this IS the sort of thing flourinert was designed for.

I've seen the stuff on e-bay for cheap.
God bless the "surplus" market.
And It comes in several forms/ grades/ Viscosities if you want your cooling less gooey.
I would think the viscose stuff would be perfect.
Don't want it sloshing around under road conditions.

Fluorinert FC-3283
Fluorinert FC-3284
Fluorinert FC-43
Fluorinert FC-40
Fluorinert FC-70
Fluorinert FC-72

Again, I would chose the "all-in-one" solution of the Peltier modules.
We used to install them on components that had to stay cooled under adverse conditions.
The ones we were supplied with had a peel-and -stick 3m adhesive on them that I couldn't believe worked, but we never had one come loose even after 100's of hard aircraft landings.

[XeonPony]

Pelts have hideous efficiency how ever, they been heavily looked at for both thermal generators, and for refrigeration with off grid systems, but the power to thermal transfer ratio is so pathetic they are not worth a look.

You can get cheap 12v dc compressors that have a way better cop

http://www.appliancedesign.com/articles ... ompressors

and they are fairly cheap.

you got 3 choices of good refrigerants

Diflouro ethane (R152a)

1,1,1,2 Tetraflouroethane (R134a)

Cyclo Propane (R290)

Only real "safe" rated one is 134a but the other two offer the better performance and efficiency

[Evoforce]

Pelts have hideous efficiency how ever, they been heavily looked at for both thermal generators, and for refrigeration with off grid systems, but the power to thermal transfer ratio is so pathetic they are not worth a look.

You can get cheap 12v dc compressors that have a way better cop

http://www.appliancedesign.com/articles ... ompressors

and they are fairly cheap.

you got 3 choices of good refrigerants

Diflouro ethane (R152a)

1,1,1,2 Tetraflouroethane (R134a)

Cyclo Propane (R290)

Only real "safe" rated one is 134a but the other two offer the better performance and efficiency

That looks like it could be a good start.

[miscrms]

I would think any cooling solution you could come up with would be very hard to compete with the built in AC in terms of both simplicity and efficiency if ambient is high enough to warrant active cooling.

At the simplest, I would think relocating the HV disconnect (or modifying the battery case adjacent to it) and adding inlet/outlet ducts to the top of the case through the existing hole in the floor would be a good start. These could even be sealed between the battery case and cabin to maintain water tight. You could probably run a duct straight from the existing foot outlet into the new battery inlet. Return would just be into the cabin. While parked you could run on foot vent only and/or close all the other vents manually to direct most of the air down into the battery. Run on its lowest setting, I would imagine power consumption would be fairly reasonable while still keeping the battery temp down. If cabin temp is considerably above ambient, using the fresh air intake might be better than recirc. For driving use you could run mixed dash/foot to mix cabin and battery cooling.

For even better performance parked you could probably duct the battery outlet back to the HVAC inlet. Maybe with a simple manual gate between cabin intake and battery for parked vs. driving. Then at least when parked the AC would only be pumping out the heat from the battery, not the cabin insolation as well. One step further, you could add a second switchable cabin air temp sensor in the battery case, and allow the Auto AC mode to maintain the air temp inside the battery rather than running it constantly on a low setting. Lots you could probably do there with CAN spoofing too if you wanted to get fancy, like just reporting the battery temp sensors back as cabin air temp?

This is pretty much what I'm planning to do with my conversion based on a wrecked Leaf. The battery will be inside the cabin, so at a minimum ambient will be cabin rather than external. I plan to experiment with ducting back into the rear hatch where the battery will be and see how much difference it makes. I generally have access to covered parking at work and a garage at home, but if needed I'll also have the option to run the AC on low while parked. My 2012 battery is down to about 85% capacity, hoping I can keep the Phoenix heat from killing it as I don't think I'm going to be a warrant replacement candidate

Rob