Active cooling your leaf battery

[Kramy]

Mineral oil is a good idea except that it would need 100~200 liters, since there's so much free space inside the pack

Err - are you sure about that? If true, yowsa, that's a lot!
https://chargedevs.com/wp-content/uploa ... y-Pack.jpg

I saw on a mineral oil cooled PC site that STEOil makes "tech-ready" (Electronics safe) mineral oil, and sell it in rather large quantities.

"Crystal Plus Tech Grade Mineral Oil 70T - 5 gal"
http://store.steoil.com/
http://www.steoil.com/msds-tech-data
http://store.steoil.com/categories/Crys ... t=featured

I was hoping one or two would do the trick. If it'd really take 10 of those, then ouch - that's nearly $1000 in mineral oil!

I see they offer it by the 55 gallon drum, though, and you have to call in for a quote. I just did, but it still came in over $500 before shipping. I have a feeling that if anywhere near 200 litres is required, it's going to make more sense to just save up for a new battery pack. (They'll drop in price within a few years, once Tesla is mass producing lithium ion batteries.)

Does anyone know how well the battery packs are sealed? It appears that if filling it up fully, a lot of oil would be in touch with the seal, and be located above it. Just wondering whether this idea would turn into a huge mess.

And to fill it up, the cover itself would have to be modded to include a sealable opening on top?

[WyrTwister]

FYI , electrical transformers have been filled with oil , for decades . I am sure it aids in cooling .

http://www.geindustrial.com/products/tr ... uid-filled

Weight is probably not an issue with stationary transformers .

However , the added weight for an EV would be a consideration .

God bless
Wyr

[Kramy]

FYI , electrical transformers have been filled with oil , for decades . I am sure it aids in cooling .

http://www.geindustrial.com/products/tr ... uid-filled

Awesome! Sounds like it's an idea on the right track.

Weight is probably not an issue with stationary transformers .

However , the added weight for an EV would be a consideration .

God bless
Wyr

Apparently 1 litre of mineral oil is somewhere around 2 pounds? Not sure exactly how much is required, but it probably would be like having another person or two in the vehicle.

Edit:

Mineral oil varies in specific gravity from 0.818 to about 0.920, depending on how refined it is.
So one US gallon weighs between 6.83Lbs to 7.68 Lbs...

From the midpoint:
5 gallons = ~19 litres.
19 litres = ~36.25 lbs.
100 litres = ~190.8 lbs.

[Andrejun]

Mineral oil is a good idea except that it would need 100~200 liters, since there's so much free space inside the pack

My theory would be to have it dribble over each cell with a few gallons at the bottom.

For whatever reason I never get notified of anything on this forum.

[Andrejun]

Or maybe some sort of rotating sprayer network (think lawn sprinkler) that would get some on each cell.
Probably easier to get a 1/4" or so piece of vinyl tube to the top of each cell. Pump in bottom of battery pack that heads to heat exchanger in the grill, then back in to the pack and distributed via above mentioned tubes.
Just a thought to keep system weight down in the 25 lb range.

[Kramy]

Active systems are more prone to failure, and possibly too energy intense depending on the flow required. The most obvious solution is to redesign the battery compartment to contain less airspace, then fill it to the brim, but I'm not an expert on moulding plastic, so that's not currently one that I could tackle.

I'm curious how much weight you would add by filling up the stock container completely?

-Kramy

[arnis]

Adding a reasonable solution (as an engineer):
make one (or two) holes (IP68).
Insert tubes (air in and air out).
Connect hose "air in" to climate control air output side (after temperature treatment) to "center vent" channel.
Hose must be pretty big, diameter at least 25mm (1").
Inside the battery divide "air in" in two (left and right side, vehicle front). Best to divide both sides in two: up and down.
So all together 4 air in holes.
In the back of the pack (behind the bigger stack) two hoses left and right connect together and
make one "air out" hose, same diameter. Add "one way valve". Air out must be purged inside
the vehicle, best near trunk air out vents.


Worst that can happen is that if vehicle will get in a flooded region (40+cm), it might ruin the battery (like iMiev).
But that is not really a reason, both ways vehicle will be scrapped.
Condensation should not be a problem, AC air is dry.

Air can be pushed harder if center vents closed/half closed.
Air will be heated in winter (not needed for hot regions, but also not bad).

[RockyNv]

I maintained electrical switch gear from the industrial revolution (built just prior to WWI) when I was head of maintenance for a number of woodworking plants in New England and those used PolyChlorinatedBiPhenols in a bath. Inside the bath there would be no insulated wires just bare metal bus bars so filling a case full of plastic parts, insulated wires, etc along with batteries that swell and burst when they fail may not be the best idea in the world. Imagine servicing a formerly 400 lb battery case full of oil contaminated with the lithium compound from the batteries that now weighs closer to 600 lbs or dealing with a fire from a lithium polymer battery soaked in oil.

The batteries in the Leaf are also like Gremlins in that you can have catastrophic failure if you get them wet so making more openings under the chassis to allow greater air flow would also increase the potential for water intrusion into the battery case causing a premature failure.

I was reading a warning that these cars needed to have the carpets and upholstery vacuumed more often than those with internal combustion engines, especially if you have pets that you transport, since cabin air vents through the battery case to cool it in the summer when the AC is running leading to the potential for the battery cooling vents from the cabin to get restricted or clogged by pet hair/dander if the car is not kept well cleaned. I have not confirmed the accuracy of this but that is what one "Leaf Expert" advised.

[arnis]

Nonsense. Leaf battery is not in any way connected with cabin carpets.
iMiEV has AC air cooled pack. Nothing happens with those vehicles (except Katrina Hurricane etc).

[sparkynz]

any one considered helium?,approx. the same thermal conductivity as mineral oil,very safe inert gas,used as a fire retardant and purge gas and cheap,small weight saving,i presume the battery pack has a vent somewhere which would need a work around.