Investor Engineering Discussions

[jerry33]

Ha. I take your bid, and raise it: Unless said resistance heater is inside a sealed box, and maybe not even then, some heat will be lost to conduction/radiation/whatever and not delivered to what one desires.

There is always energy loss when energy is converted from one form to another.

 

[navguy12]

Ha. I take your bid, and raise it: Unless said resistance heater is inside a sealed box, and maybe not even then, some heat will be lost to conduction/radiation/whatever and not delivered to what one desires.

…and somewhere in Mark Jacobson’s book No Miracles Needed, How Today’s Technology Can Save Our Climate and Clean Our Air, he agrees with you. Can’t find the exact page or quote, but in his modelling math, his COP for resistance heat is less than 1…IIRC, something close to .98

 

[mongo]

There is always energy loss when energy is converted from one form to another.

Ha. I take your bid, and raise it: Unless said resistance heater is inside a sealed box, and maybe not even then, some heat will be lost to conduction/radiation/whatever and not delivered to what one desires.

Sure, but that's a systems level issue
Unless the heater is converting energy to matter, all the energy consumed eventually turns to heat.

 

[jerry33]

Sure, but that's a systems level issue
Unless the heater is converting energy to matter, all the energy consumed eventually turns to heat.

This is pedantic, but resistance heating changes electricity into heat, so there is a state change.

 

[mongo]

This is pedantic, but resistance heating changes electricity into heat, so there is a state change.

Sure, I didn't say there wasn't, but the use of electrical potential to increase kinetic energy can't result in the loss of energy (in any form). Low frequency kinetic turns into heat via friction. RF/ light (assuming a sealed box) will eventually convert to heat.
(This is all being silly)

 

[mongo]

I'm somewhat versed in acoustics as a hobby for a long time, It's impressive how inefficient most (if not all with some really rare exceptions) speakers are

For example, this is an automotive 8" subwoofer in a ported enclosure, yes, you read it right, don't even reach 10% efficiency and that is over a narrow frequency range, overall it is on the 2 to 3% average efficiency, and this is with all the gain a vehicle cabin provides, in residential or comercial applications where you have less boundary reinforcements, you usually don't break 5%

The inefficiency of a amplifier is dwarfed by the inefficiency of speakers

View attachment 1014071

Needs a better impedance matching network, might I suggest a horn?

Whereas lost power on the amplifier is heat, some (much?) of the waste energy in a speaker comes from accelerating and decelerating the cone. That generates less self heating.

Humm... regenerative audio amplifiers? Nah, Q is probably too low.

 

[GhostSkater]

Needs a better impedance matching network, might I suggest a horn?

Whereas lost power on the amplifier is heat, some (much?) of the waste energy in a speaker comes from accelerating and decelerating the cone. That generates less self heating.

Humm... regenerative audio amplifiers? Nah, Q is probably too low.

Need to invent a space compacting device, so we can fit big horns on cars, and this is coming from someone that has a 6.5 feet tall horn subwoofer in his bedroom

 

[wws]

Need to invent a space compacting device, so we can fit big horns on cars, and this is coming from someone that has a 6.5 feet tall horn subwoofer in his bedroom

There was an Altec Lansing ad back in the day that had a drawing of a convertible with a pair of A7s in the back seat.

 

[Tronguy]

Need to invent a space compacting device, so we can fit big horns on cars, and this is coming from someone that has a 6.5 feet tall horn subwoofer in his bedroom

Been done. Blues Brothers. From Pininterest:

 

[mongo]

We need superconducting amps.

That wouldn't help, an amp needs partial blocking, otherwise it's just a switch.
If there was a rapidly switchable superconductor, that would be interesting.

 

[GhostSkater]

That wouldn't help, an amp needs partial blocking, otherwise it's just a switch.
If there was a rapidly switchable superconductor, that would be interesting.

Ok, superconducting speakers, that would definitely help, ignoring the huge complications

 

[scaesare]

That wouldn't help, an amp needs partial blocking, otherwise it's just a switch.
If there was a rapidly switchable superconductor, that would be interesting.

Yeah, I was thinking of just the resistive losses for components for which that was just an unwanted byproduct...

 

[GhostSkater]

Yeah, I was thinking of just the resistive losses for components for which that was just an unwanted byproduct...

Resistive losses in a class D amp is applied to milliohms order of magnitude, while on the speakers it's ohms

Not saying there isn't improvements to be made, but amps are already close to 90% efficient

 

[mongo]

Yeah, definitely need a the equivalant of a HVJB in there.

Which makes me wonder, do CCS vehicles leave their on-board charger outputs connected to the pack diring DC fast charging? In other words, are those currently inactive chargers seeing 400-800V on their output terminals from the DCFC?

(probably should go to the engineering thread)

I believe so. It allows the charger to monitor the full pack voltage and to do otherwise would require more contactors (lower power ones, at least).

 

[scaesare]

I believe so. It allows the charger to monitor the full pack voltage and to do otherwise would require more contactors (lower power ones, at least).

Good point.

And the HVJB only switches the NACS connector to the pack, and now that I think about it, when I opened up my charger I don't recall any contactors on the outputs... so CCS chargers are probably similar...

 

[transpondster]

Just something random that I just noticed, Tesla does have different charging times for different regions depending on which cells are being used there, which is obvious they would but might be a good way to find out which battery pack goes where

For example, in the US Model 3 charges 51.3% in 15 minutes, in Europe it's 44.8%

Someone asked a while ago where from the vehicles for Chile will come, the percentage in 15 minutes there is 44.8%, so it the information is correct, they will be Shanghai made with LG cells

Weirdly enough, for Model Y is 39.7% in 15 minutes, unless now there is one more battery pack with LG cells into the mix that charges slower

You are probably seeing LG vs Panasonic, not regional differences for the same packs.

 

[GhostSkater]

You are probably seeing LG vs Panasonic, not regional differences for the same packs.

Yep, this is my point, knowing the charge times allows us to know where vehicles are coming because, at least until recently the was no LG packs in the US

Which makes it more weird now, because US Model 3 with LG cells shouldn't charge faster, which might mean it's back to having Panasonic cells?

 

[Buckminster]

https://twitter.com/x/status/1758259035499798896

Clean and tidy

 

[navguy12]

https://twitter.com/x/status/1758259035499798896

Clean and tidy

I’m only familiar with my vacuum tube powered, steam driven May 2018 build TM3.

What is this cylinder that appears at the base of the port side frunk hydraulic strut?

 

[Dikkie Dik]

I’m only familiar with my vacuum tube powered, steam driven May 2018 build TM3.

What is this cylinder that appears at the base of the port side frunk hydraulic strut?

View attachment 1018984

I believe there’s one on either side, in case of an pedestrian impact the hood of the car is raised to create more space underneath to cushion the blow.


Edit:

https://www.tesla.com/ownersmanual/model3/en_eu/GUID-FCD87BBA-BA45-4955-8E3A-2FEBBA7DE9FA.html