Electric Cars - the discussion continues.

[facthunter]

If it  could be done you'd have perpetual motion. Energy of low wavelength is not as useful as energy at a high temperature and the inevitable flow is from high to low(er). No amount of hot water will produce incandescent white hot filaments but such filaments can heat water but be waste of opportunity to do better things with it. Sunlight can be concentrated to make white hot SALT which is far more useful that warm water in a swimming pool from black poly pipes on your roof  A SOLAR panel goes one step further and produces electricity directly. Nev

[Bruce Tuncks]

Nev alluded to the second law earlier. Any heat engine has a maximum efficiency denoted by the law that entropy must increase.. Entropy is roughly the transferred heat divided by the kelvin temperature. In the real world, efficiencies of 25 % are usually the max possible. The greater the difference in temperature between combustion ( or high temperature working fluid ) and the exhaust then the greater the efficiency...  this is why diesel engines get better mileage.

Electric motors are NOT heat engines and don't follow this rule. But the generators at the power station, driven by turbines, do.

[facthunter]

 Indeed. Heat change achieved equates to efficiency in all CARNOT cycle engines. Thats why jet engines go for increasingly higher Turbine temperatures and higher pressure ratios..  You don't have to build and test new steam engines though. You can determine the efficiency before they are built and not bother.. (Much as I love their character). IF you DO distilling you will understand things better as the distilling process is dependent on it.. Your old cement mixer engine will not overheat as along as some water is still in the tub surrounding the hot parts, boiling away. .  Nev

[spacesailor]

The heat exchanger uses the colder water ( in the water tank ), to help condense the end ' low pressure, wet steam vapor  , into into distilled water. then pumped into the water tank, saving most of the wasted water, that would have been discharged to the air .

spacesailor

[facthunter]

That's a sealed system I mentioned way back. That saves having to provide quite a lot of water.  Nev

[red750]

US farm machinery manufacturer John Deere allows farmers the right to repair tractors

 

https://www.msn.com/en-au/money/markets/us-farm-machinery-manufacturer-john-deere-allows-farmers-the-right-to-repair-tractors/ar-AA169fNa?rc=1&ocid=winp1taskbar&cvid=764851e525e5409de01106cd4ca04b97

[red750]

On electric vehicles in general, some frightening videos on electric buses.

 

 

https://www.youtube.com/watch?v=5r-yN8SugWM

 

https://www.youtube.com/watch?v=Xlyh6z12zgw

 

[onetrack]

There's definitely been a worrying increase in Li-ion battery fires here in Australia, that has the firies concerned.

 

A lot of the problems, though, are related to using the wrong type of charger, overcharging, and leaving the charger unattended.

[facthunter]

Maybe an overtemp relay? Nev

[nomadpete]

Every BMS (battery monitor system) monitors battery temp, and voltage. Even on single AAA cells.

Bigger batteries have BMS also watching charge current, and individual cell voltage.

We even do this with lead acid batteries in telco repeaters. But especially, with Lithium Ion ones. Also, some BMS are set to cut charging off at 90% in order to give max cycling life to the battery.  So in theory they should never get to thermal runaway.

 

I wonder if these fires are a result of BMS faults rather than battery faults? A bit difficult to do a forensic investigation after such intense fires though.

[nomadpete]

If I have the option I will hold off buting a EV until the next gen of battery technology comes out.

 

I'm looking forward to it.

[kgwilson]

LiFeP04 lithium batteries do not have the possible thermal runaway problem. These are being used in a a large number of EVs now. Even so standard Lithium batteries do not have this problem very much and as far as cars are concerned EVs are far less likely to catch fire that ICE cars. A study in 2020 found that fires per 100,000 sales were. ICE 1530, Hybrid 3475, and Battery Electric 25. It is not even close. EVs are far more fire resistant than anything else. Hybrids are the worst by a country mile. Having a volatile fuel around a lot of electrics is a recipe for disaster as it seems to prove.

 

Once sodium ion batteries replace lithium the problem goes away as well as being at least 30% cheaper to produce.

[octave]

 

 

EV Fires: Less Common But More Problematic?

 

A lot of EVs are using LFP batteries which I believe are less likely to catch fire.    I have had a car catch fire whilst driving.   Back 1999 I was driving home from work on a warm summer evening when i started to smell smoke. I thought there must be a bush fire until U realized the smell was stronger inside than outside.   This vehicle was a Mitsubishi L300 (seat over the engine) I had to call the fire brigade and the vehicle was a right off.   

 

EV fires are much rarer than ICE fires however the results are often more dramatic. 

[Bruce Tuncks]

I have seen 2 model planes catch fire in the air. One came down in a gum tree and dropped flaming bits of foam on the ground underneath. One simply smoked and it was landed and taxied up to a powder fire extinguisher. These were both LiPO's, and not LiFe batteries.

[facthunter]

Even a lead-acid can overheat and short out if something goes wrong with the voltage regulator. I've had it happen in a tractor and my son recently rang me saying his battery was smoking and too hot to get at to remove it I told him to keep it cool with the hose, which worked fine. The energy has to go somewhere. New  alternator and battery and drive belt. Under $500 done by himself. The battery was quite old, so still don't know what happened first. IF it was in a plane.(Much the same stuff) it would be a different matter..Nev

[Bruce Tuncks]

I read that LiFe are not flammable but I reckon that if it were shorted out, the energy would make lots of fumes etc. I don't want to experiment myself, but the kid once hung a Li PO ( charged) on a fence and shot it. It made a satisfying firework he said.

I reckon Jabirus are correct in having the battery on the other side of the firewall than the pilot . I know of another plane where you sit over the battery.

[onetrack]

I read a major scientific article a number of months ago where they compared the Li-Fe battery to the Li-ion with regard to flammability.

The difference was substantial. The Li-ion would go off like a Roman candle, whereas the Li-Fe only smouldered heavily.

 

All batteries, when charged, contain substantial levels of energy, and it has to be dissipated somehow, when a major short is involved.

Lead acid batteries shorting out can produce some spectacular fireworks, and lots of heat. A lot of amperage on the rampage.

 

One of the major factors that people don't think about with Lithium battery fires, is the extreme toxicity of the smoke and chemical ingredients from a lithium battery fire.

In a confined area where the smoke and chemical fumes will congregate, this will kill you in a very quick period of time, as compared to the threat posed by actual fire and flame.

 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5577247/

[onetrack]

Now, Tesla is really ramping up the pressure on the other automotive manufacturers. At a very recent investor presentation, Musk is claiming major advances in Tesla technology, on multiple fronts.

 

1. They are now producing a new, incredibly efficient electric motor.

2. They have eliminated the use of rare earth metals in the construction of their vehicles motors and electronics

3. They have reduced the amount of electronics in their cars, whilst improving overall efficiency

4. They have reduced the level of heat being generated when their vehicles are operating

5. They have reduced their factory sizes by a staggering amount, via increased automation, AI and efficiency.

6. They are aiming at a vehicle cost of under US$25,000, and possibly even as low as US$16,000, according to some analysts.

7. They are bragging about how everything is done in-house, and as a result, they can keep reducing their costs, whilst increasing the efficiency of their cars (and now trucks).

 

They also point out that their battery is optimised for low cost manufacturing, rather than ever-increasing energy density, so the advances they have made in motor design and electronics efficiency, more than compensates for no major increase in battery energy density.

 

 

[Jerry_Atrick]

I'm gonna wait for John Cadogan's asessment.

 

[Old Koreelah]

On 7/2/2023 at 12:55 PM, onetrack said:

…All batteries, when charged, contain substantial levels of energy, and it has to be dissipated somehow, when a major short is involved.

Lead acid batteries shorting out can produce some spectacular fireworks, and lots of heat. A lot of amperage on the rampage.

This topic led to much discussion at my mechanic mate’s garage yesterday. Everyone had stories of Lead batteries exploding-and doing people immense harm- and Pb Acid batteries have had over a century to be perfected.

 

The Lithium battery packs used in EVs have a good safety record, but many of them are mounted right under the rear passenger seat. Some depend on being kept cool via an electric blower that sucks air from the cabin. Very few of the filter pads ever get replaced, so a blocked filter is a fire hazard.

 

Today I hope to finish installing the “battery ejector” on my camper. A big LiFePO4 battery behind the left wheel, suspended by three ratchet straps. If it catches fire, the polyester straps instantly melt and it drops and slides back onto the ground. 

Very unlikely for this battery chemistry, but it is a cheapie, so who knows how safe it is?
 

[red750]

Once again, simply posting what someone sent me, without comment. Far more intellectual minds here to disect it.

 

To all you great thinkers.

Ponder this:

 

Imagine Brisbane with a hurricane coming toward the coast.

 

The premier orders an evacuation. All cars head South. They all need to be charged in Newcastle.

How does that work? Has anyone thought about this?

 

If all cars were electric, and were caught up in a three-hour traffic jam with dead batteries, then what?

Not to mention that there is virtually no heating or air conditioning in an electric vehicle because of high battery consumption.

 

If you get stuck on the road all night, no battery, no heating, no windshield wipers, no radio, no GPS (all these drain the batteries), all you can  do is try calling 000 to take women and children to safety.

But they cannot come to help you because all roads are blocked, and they will probably require all Emergency Vehicles and Police cars to be electric also.

 

Later when the roads become unblocked still no one can move! Their batteries are dead. How do you charge the backlog of cars in the traffic jam? Same problems during summer holiday departures with possible heavy traffic jams. There would be virtually no air conditioning in an electric vehicle. It would  drain the batteries too quickly.

 

Where is this electricity going to come from? Today's grid barely handles users' needs now. Can't use nuclear. There’s only 50 years worth of Helium left in the atmosphere and we need that. Hydrogen is still too expensive  and hard to handle, Oil and coal fired is out of the question, then where?

 

What will be done with billions of dead batteries, can’t bury them in the soil, can’t go to landfills. Can’t get them wet, lithium explodes into raging fires. So don’t call the Fire  Services if you have an accident. The cart is way ahead of the horse.

 

There has been very little thought whatsoever to handle any of the problems that batteries can cause.

[Jerry_Atrick]

*sigh*

 

Your turn, @Marty_d 😉

 

Long weekend here to celebrate Chas' coronation chicken.. or something like that...

 

[edit]

But... current tech EVs and the current ownership model of cars will not solve climate change anyway.  So, it's sort of a moot post, anyway..

 

[edit][edit]

There are better ways to achieve emissions reductions, apparently:

 

Edited May 5, 2023 by Jerry_Atrick

[nomadpete]

We'll all be rooned...... Said Red

[nomadpete]

Just loved his summary of 'what a politician is'

[red750]

Waiting for a charging station...