Cooling an electric vehicle battery. (2023 Update)

The same time Tesla knew to control the temperature of their batteries. That is fundamental of not just lithium but all batteries. Batteries are electrochemical and chemical reactions are very temperature dependent.

Yes, I have no doubt. That is my point.

At least i don't drive into flashing red and blue with FSD.

Thermal inertia means that the temperature probably won't go up much.Batteries have got quite a lot of thermal mass.

ICE vehicles produce a lot more waste heat. Thermal inertia doesn't help nearly as much.

The whole point about heat pipes is that heat is transferred as latent heat of evaporation in vapour that has boiled off the hot surface and condenses at the heat sink.

The vapour has a lot lower viscosity than any liquid coolant, and flows a great deal faster - the limit seems to be speed of sound in the vapour - and it is transferring an order of magnitude or two more heat in each unit mass of vapour.

You could certainly use a pump to transfer liquid back from the heat sink - where it would condense - to the hot spots which is is cooling by evaporating.

The small heat sinks used to cool electronic devices don't bother - they just let it wick back along the inner surface of the pipe that carries the stream of vapour in the other direction. You got to keep the heat-pipe vacuum tight - any non-condensible gas in the path slows down the vapour flow rate horribly. Hydrogen and helium have a nasty habit of diffusing in if there is any around, but it doesn't happen fast.

Makes a fuss about the mechanisms they use to control battery temperature. Pumping coolant through batteries is an obvious way to do it, but I'd not heard about it.

It's also a whole lot messier than a heat pipe. My 1996 paper spells out how I initially made exactly the same mistake in the original design of our thermostat and I'd been away for a few months before Douglas Stewart had the bright idea of cooling our Peltier junction with a heat-pipe assembly rather than circulating water.

I would have loved to have come up with the idea, but we'd been busy putting together something that worked rather than making tricky changes that might - and in fact did - make it work better.

It certainly strikes me that way.

SL0WMAN doesn't understand batteries or electric vehicles much, that is clear. Most of the energy loss in electric cars is in the electronics, not the battery. For example, charging accounts for up to 25% of energy loss:

Energy loss in the battery is the result of its internal resistance, which is, by design, very low. Here is a more intelligent review of the losses (scratch "more'): car manufacturers keep battery temperatures down because heat literally destroys the batteries. The Leaf did not do this and suffers from much faster battery degradation than Tesla.

It's a matter of how much money you are throwing at the cooling issue. Leaf opted for simplicity and safety and completely sealed the battery. Since it had relatively low incidences of fire, we might be able to relax the safety concern. Namely, opening accesses from the top cover.

This guy has the right idea of blowing A/C air into the HV cut-off port, but not going far enough. Modifying or simply removing the top cover would allow cold air to blow in from the center and out of the sides.

Neither does Flyguy, but Flyguy is much too stupid to appreciate how little he understands.

I was talking about the power put into the battery and subsequently taken out again. What the car does with it after it has left the battery didn't come into it - that heat is dissipated elsewhere, and isn't interesting in this particular context (which Flyguy seems to have ignored - that sort of stuff is too complicated for him to follow).

" Roughly halving the peak temperature inside the battery should make them last longer" expresses much the same sentiment, but Flyguy can't understand this.

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Not sure why you are talking about ICE in a conversation about battery temperature. The point is there are situations where the discharge of the battery causes significant heating of the battery constrained only by the power being used by the vehicle. The thermal mass of the battery won't prevent temperature rise any more than when charging. With a higher discharge rate than is allowed during charging the discharge is the situation that can cause more damage to the battery and sets the requirement for cooling. There are plenty of mountains that tax a vehicle's power capacity, doubly so when towing.

Yes, we all know how heat pipes work.

So why aren't they using heat pipes in auto batteries? Because the issue you are talking about is not what is important. You don't address the issue of getting the heat from the heat pipes into a cooling system or the environment. The heat pipes in PCs terminate in relatively massive heat sinks that in turn dissipate the heat to air that is blown across large heat sinks. That's not practical in an auto adding increased weight. Instead they would use a water block and end up with a water cooled battery anyway. Heat pipes would not be solving any problems EVs currently have.

To what end? Where is the advantage?

What are you talking about??? Teslas have water cooled and heated the batteries since day one a decade ago. I guess you've been out of the loop on how they operate.

Perhaps you aren't aware that every thermal design problem is not identical. In addition to the specific thermal requirements, there are the practical issues involved. I can't say what all the issues might be, but talking about the velocity of vapor in a heat pipe is only one, small issue in this matter.

Can you explain exactly what it would improve on? Is there any reason to think it would be practical in an EV application?

It is obvious that I understand them a hell of a lot MORE than you do! You have claimed that LIB don't burn, for example, provably false.

You don't know WHAT you are talking about. You change your story once I show you have your head up your ass.

Fuck you SL0WMAN - I STATED that very clearly, you idiot!

More snipping by the idiot who complains that I SNIP!

Do you have any evidence to say the Nissan battery has a lower incidence of fire than the Tesla batteries?

This is the sort of absurd stuff you are famous for. Just buy an EV that actually works properly.

There is only one known case for the Leaf. 21 for Tesla. 20 for Bolt.

Leaf:

1. September 1, 2015, Flower Mound, Texas

Tesla:

1. October 1, 2013, Model S, Kent, Washington
2. October 18, 2013, Modl S, in Merida, Mexico
3. November 6, 2013, Model S, Murfreesboro, Tennessee
4. November 15, 2013, Model S, Irvine, California
5. January 1, 2016, Model S, Norway
6. August 15, 2016, Model S 90D, Biarritz, France
7. August 25, 2017, Model X Forest, California,
8. May 8, 2018, Model S
9. May 10, 2018, Model S, Monte Ceneri. Germany
10. June 16, 2018, Model S, Los Angeles, California
11. February 8, 2019, Model S, Pittsburgh. PA
12. February 24, 2019, Model S, Davie, Florida
13. February 24, 2019, Model X, Lake Champlain.
14. April 21, 2019, Model S, Shanghai, China.
15. May 4, 2019, Model S,
16. May 13, 2019, Model S, Hong Kong.
17. June 1, 2019, Model S, Belgium.
18. August 10, 2019, Model 3, Moscow, Russia
19. November 12, 2019, Model X, Chester, England.
20. January 19, 2021, Model 3, Shanghai, China
21. July 2021, Model S Plaid

Leaf works fine with the simple topless fix.

"Known" cases. How many unknown cases of Nissans catching fire? Tesla always gets the bad press because it is the guy on top of the heap and everyone likes to find every problem with it. I believe there are 150,000 ICE fires each year in the US. None of these EV numbers indicate a "problem" in comparison.

If it works "fine", why does it need a fix?

Why not just buy a car that works without home brew, jury rigged modifications???

Same ratio as unknown Tesla fire. There are lots of "totalled" Leaf with battery intact. Not too many with Tesla.

It will work better.

Leaf works well enough for me. I just need to find the right time and place to do it. Lower the battery. Remove the cover. Make several taps into the modules. Remount the battery. Should take a day or two, mostly making the taps from the main battery to my spares in the door frame and under the hood.

The main concern is water getting into the HV switch port. I would cap the host when not in use. As shown in my accidental experimental incident, the Leaf floats on water. So, the risk of water flooding the battery is very low.

The key part of that is "for me". You seem to have tolerance for things no one else on earth has. You bought an EV with 50 miles of range or less and spend hours and hours sitting at level 2 chargers on trips over 100 miles. In some cases you have had to plug into 120V outlets. No one else in the world wants to deal with that nonsense. You are literally the poster child for range anxiety, sitting at a closed gas station trying to get another kWh on your car so you can get to the next gas station.

You are going to kill yourself with these mods to car. You are the sort of person they create the "idiot" laws for.

LOL!!!

Not anymore. There are at least 30 FREE FAST chargers in California. For those I use, there are 5 on 99, 3 on I-5, 2 on I-15 and 1 on I-58. I only need 3 to 4 L2 if i want to avoid paying for fast charging.

No need for this:

My taps will be 100V to 150V. If you are afraid of the little electricity, you are in the wrong news group.

You are proving my point. You don't even understand what I'm talking about, but that's par for the course.