Go Back  British Expats > Living & Moving Abroad > USA > The Trailer Park
Reload this Page >

Let's talk about cars

Let's talk about cars

Old Aug 24th 2020, 9:58 pm
  #7486  
Lost in BE Cyberspace
 
Steerpike's Avatar
 
Joined: Nov 2007
Location: Bay Area, CA
Posts: 13,193
Steerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Giantaxe
"Braking" puts the electric motor into reverse. The more you brake - either through the brake pedal or paddle shifters - the faster electric motor goes in reverse, the more the vehicle slows, and meaning the turbine (or whatever it's called on an electric vehicle) spins faster thus generating more electricity.

Here's a reasonable description:

https://auto.howstuffworks.com/auto-...ve-braking.htm


This is why hybrids have higher fuel economy in the city rather than the highway - the relatively frequent braking that is happening charges the battery making it available for subsequent acceleration. When you're on the highway you are typically braking less, so there is less opportunity per mile for regenerative braking. Another side effect should be that braking components - including brake pads - last longer. Regenerative braking doesn't remove the need for "regular" brakes - apparently it's not as effective as speed reduces towards zero - but it should reduce their use. I get approx 50k on my front brake pads on my BMW - will be interesting to see how long the Honda pads last for.
I'm familiar with the concept and the high level description in the article. We also have a Prius so I get to experience it first hand on a daily basis . As soon as you take your foot off the accelerator (and assuming you are going downhill for the purposes of this discussion), you 'coast' or 'roll', and the wheels become generators and the generated electricity is fed back into the battery. On the prius, you see this graphically on the dash display.

Here's what I'm not clear on. Let's make a distinction between coasting and braking; assume two scenarios - 1) on a gentle downwards slope, you are coasting along at 60 mph with no foot on the accelerator and no foot on the brake (wind resistance and rolling resistance is what stops you from going faster and faster). 2) on a slightly steeper downwards slope, you are also going at a steady 60 mph, but this time, due to the increased slope, you are gently applying the brakes to stop you from going faster than 60 mph. Let's assume in this second scenario that the 'braking' force is not great, and is supplied by 'regenerative braking' and not the friction pads.

So, in scenario 1, at 60 mph, the wheel motors will generate a certain amount of electricity which will charge the battery. In scenario 2 at 60 mph, the wheels are rotating just as fast, but since there is regenerative braking going on, are the wheel motors generating more, or less, electricity for the battery charging system?

From the description of 'regenerative braking', it sounds like electricity from your battery is fed to the wheel motor in reverse, to apply reverse rotational torque to the wheels, in order to slow you down; this would suggest a less efficient situation compared to scenario 1. The article says "When the driver steps on the brake pedal of an electric or hybrid vehicle, these types of brakes put the vehicle's electric motor into reverse mode, causing it to run backwards, thus slowing the car's wheels". The article goes on to say "While running backwards, the motor also acts as an electric generator, producing electricity that's then fed into the vehicle's batteries. "

So comparing the two scenarios - 1) rolling down a hill at 60 mph and 2) regenerative braking while rolling down a hill at 60 mph, which is putting more electricity back into the battery? My opinion is, you are going to get the most 'battery charge' out of the free-fall roll, without brakes. Once you apply the brakes you will get less charge put back into the batteries. But I'm not convinced!

The fact you have 'paddles' that can increase / decrease the regenerative effect is very interesting ... what exactly is it increasing ...

ETA - just re-read your comment "The more you brake - either through the brake pedal or paddle shifters - the faster electric motor goes in reverse, the more the vehicle slows," now, maybe that's the part I'm struggling with. My understanding is, the motors on the wheels are direct connected - the motor spins with the wheel, so the motor speed is identical at all times to the wheel speed, which at, say, 60 mph is going to be a set rpm of the wheel.

Last edited by Steerpike; Aug 24th 2020 at 10:01 pm.
Steerpike is offline  
Old Aug 24th 2020, 10:38 pm
  #7487  
Lost in BE Cyberspace
 
Joined: Jan 2006
Location: San Francisco
Posts: 12,865
Giantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond reputeGiantaxe has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Steerpike
I'm familiar with the concept and the high level description in the article. We also have a Prius so I get to experience it first hand on a daily basis . As soon as you take your foot off the accelerator (and assuming you are going downhill for the purposes of this discussion), you 'coast' or 'roll', and the wheels become generators and the generated electricity is fed back into the battery. On the prius, you see this graphically on the dash display.

Here's what I'm not clear on. Let's make a distinction between coasting and braking; assume two scenarios - 1) on a gentle downwards slope, you are coasting along at 60 mph with no foot on the accelerator and no foot on the brake (wind resistance and rolling resistance is what stops you from going faster and faster). 2) on a slightly steeper downwards slope, you are also going at a steady 60 mph, but this time, due to the increased slope, you are gently applying the brakes to stop you from going faster than 60 mph. Let's assume in this second scenario that the 'braking' force is not great, and is supplied by 'regenerative braking' and not the friction pads.

So, in scenario 1, at 60 mph, the wheel motors will generate a certain amount of electricity which will charge the battery. In scenario 2 at 60 mph, the wheels are rotating just as fast, but since there is regenerative braking going on, are the wheel motors generating more, or less, electricity for the battery charging system?

From the description of 'regenerative braking', it sounds like electricity from your battery is fed to the wheel motor in reverse, to apply reverse rotational torque to the wheels, in order to slow you down; this would suggest a less efficient situation compared to scenario 1. The article says "When the driver steps on the brake pedal of an electric or hybrid vehicle, these types of brakes put the vehicle's electric motor into reverse mode, causing it to run backwards, thus slowing the car's wheels". The article goes on to say "While running backwards, the motor also acts as an electric generator, producing electricity that's then fed into the vehicle's batteries. "

So comparing the two scenarios - 1) rolling down a hill at 60 mph and 2) regenerative braking while rolling down a hill at 60 mph, which is putting more electricity back into the battery? My opinion is, you are going to get the most 'battery charge' out of the free-fall roll, without brakes. Once you apply the brakes you will get less charge put back into the batteries. But I'm not convinced!
The benefit of regenerative braking is that it is able to convert the kinetic energy of the vehicle into electricity stored in the battery. If the braking reduces the speed of the vehicle from, say, 60mph to 40mph the kinetic energy with normal braking is released in the form of heat through friction with the brake pads. With regenerative braking, it ends up being "released" in the form of electricity. So I'm not even sure your comparison is too meaningful as it's of different circumstances. In your scenario (ii) it's the braking that maintains the steady 60 mph (and thus there _is_ a capture of kinetic energy; absent the braking the car would speed up). In your scenario (i) it's solely air friction/rolling resistance that's keeping a steady 60mph and there is no other kinetic energy that can be recaptured.

Originally Posted by Steerpike
ETA - just re-read your comment "The more you brake - either through the brake pedal or paddle shifters - the faster electric motor goes in reverse, the more the vehicle slows," now, maybe that's the part I'm struggling with. My understanding is, the motors on the wheels are direct connected - the motor spins with the wheel, so the motor speed is identical at all times to the wheel speed, which at, say, 60 mph is going to be a set rpm of the wheel.
That I'm not convinced of. And when I use the paddle shifters I see a clear increase in the rate the battery recharges, presumably because of the increase in kinetic energy that's available for regeneration.

Last edited by Giantaxe; Aug 24th 2020 at 10:48 pm.
Giantaxe is offline  
Old Aug 24th 2020, 10:47 pm
  #7488  
BE Forum Addict
 
zzrmark's Avatar
 
Joined: Apr 2014
Location: Lauren's Co. SC by way of Palmetto, Florida
Posts: 3,267
zzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by johnwoo
I had a 1998 3.0L V6 and gave it to my grandson when I bought my current 2014 Accord Sport. Never changed the timing belt and nor did he until the thing gave out due to lack of care or maintenance. probably had an excess of 160,000 miles
160k is barely run in for those 3l engines.
zzrmark is offline  
Old Aug 24th 2020, 11:29 pm
  #7489  
Lost in BE Cyberspace
 
Steerpike's Avatar
 
Joined: Nov 2007
Location: Bay Area, CA
Posts: 13,193
Steerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond reputeSteerpike has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Giantaxe
The benefit of regenerative braking is that it is able to convert the kinetic energy of the vehicle into electricity stored in the battery. If the braking reduces the speed of the vehicle from, say, 60mph to 40mph the kinetic energy with normal braking is released in the form of heat through friction with the brake pads. With regenerative braking, it ends up being "released" in the form of electricity. So I'm not even sure your comparison is too meaningful as it's of different circumstances. In your scenario (ii) it's the braking that maintains the steady 60 mph (and thus there _is_ a capture of kinetic energy; absent the braking the car would speed up). In your scenario (i) it's solely air friction/rolling resistance that's keeping a steady 60mph and there is no other kinetic energy that can be recaptured.
To clarify / elaborate a bit, in the Prius, when you take your foot off the accelerator pedal, and you are in a downhill situation, you feel a definite 'resistance' that seems stronger than just air resistance. AND - you see the charging indicator show charging of the battery. So - it's my understanding that, as soon as you are not 'accelerating' (providing electricity to the wheel motors), you are essentially re-generating. You don't have to apply the brake pedal in order for regeneration to occur. Of that, I'm 99.9% sure. So when you are 'coasting', you are in fact feeling the effect of the wheels being used as generators.

Originally Posted by Giantaxe
That I'm not convinced of. And when I use the paddle shifters I see a clear increase in the rate the battery recharges, presumably because of the increase in kinetic energy that's available for regeneration.
I suspect I'm greatly over-simplifying the design of the wheel motors in my mind. That article talks about 'going in reverse' which may indicate a real reversal (obviously, the wheel itself is always going in the same rotational direction - unless you are going in reverse ). So what I'm fairly positive about is, you take your foot off the accelerator, and the wheels immediately become generators; but maybe as you apply the brake, something is done to increase further the generation capacity of the wheel motors.

What do you see on your CRV charge indicator when you roll downhill (without braking)? The Prius has a very sexy diagram about what's going on with the battery (highly distracting, actually!) I'm almost +ve that it shows charge to the battery when 'rolling' (coasting / no brake). Of course google is not being cooperative in showing me such an image right now! I live on a hill so next time I go out I'll pay specific attention to the 'downhill roll' part!

I think my real question is - what happens differently when you coast down a hill versus apply the brake gently down a hill ...

Last edited by Steerpike; Aug 24th 2020 at 11:32 pm.
Steerpike is offline  
Old Aug 25th 2020, 1:23 am
  #7490  
Lost in BE Cyberspace
 
mrken30's Avatar
 
Joined: Jul 2008
Location: Portlandia Metro
Posts: 7,427
mrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond repute
Default Re: Let's talk about cars

Cars like the Tesla, Chevy Bolt, have the option for one pedal driving. The regen brakes will bring the car to a halt and allows you to drive using a single pedal. Down for go, up for stop.
mrken30 is offline  
Old Aug 25th 2020, 10:55 am
  #7491  
BE Forum Addict
 
zzrmark's Avatar
 
Joined: Apr 2014
Location: Lauren's Co. SC by way of Palmetto, Florida
Posts: 3,267
zzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by mrken30
Cars like the Tesla, Chevy Bolt, have the option for one pedal driving. The regen brakes will bring the car to a halt and allows you to drive using a single pedal. Down for go, up for stop.

That is like the concept of the Dutch bicycle, have you ever ridden one of those contraptions? They sound great in theory and the locals make it look like a doddle but if you're used to having proper brakes it takes some getting used to!
zzrmark is offline  
Old Aug 25th 2020, 11:05 am
  #7492  
 
Nutek's Avatar
 
Joined: Apr 2012
Location: CT
Posts: 33,566
Nutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond reputeNutek has a reputation beyond repute
Default Re: Let's talk about cars


Nutek is offline  
Old Aug 25th 2020, 3:27 pm
  #7493  
Thread Starter
 
Pulaski's Avatar
 
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,490
Pulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by mrken30
Cars like the Tesla, Chevy Bolt, have the option for one pedal driving. The regen brakes will bring the car to a halt and allows you to drive using a single pedal. Down for go, up for stop.
Originally Posted by Nutek
Honestly, I would be more interested in discussing one of these.


Pulaski is offline  
Old Aug 25th 2020, 3:36 pm
  #7494  
Stand-up Philosopher
 
caretaker's Avatar
 
Joined: Apr 2009
Location: Regina Saskatchewan
Posts: 16,344
caretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond reputecaretaker has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Pulaski
Honestly, I would be more interested in discussing one of these.

1982 Lada.
caretaker is offline  
Old Aug 25th 2020, 3:51 pm
  #7495  
Thread Starter
 
Pulaski's Avatar
 
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,490
Pulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond repute
Default Re: Let's talk about cars

Does any one have experience with TVR's?

I am mulling over the idea of importing one (that is over 25 years old), and there are a couple of interesting options. I know it would be a bit of a money pit, and yes, I know they're notoriously unreliable, but the prices aren't bad. It wouldn't be happening any time soon, probably 2-3 years at best, so I have enough time to do my homework.
Pulaski is offline  
Old Aug 25th 2020, 8:12 pm
  #7496  
BE Forum Addict
 
zzrmark's Avatar
 
Joined: Apr 2014
Location: Lauren's Co. SC by way of Palmetto, Florida
Posts: 3,267
zzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Pulaski
Does any one have experience with TVR's?

I am mulling over the idea of importing one (that is over 25 years old), and there are a couple of interesting options. I know it would be a bit of a money pit, and yes, I know they're notoriously unreliable, but the prices aren't bad. It wouldn't be happening any time soon, probably 2-3 years at best, so I have enough time to do my homework.
Do you have an engine or model type in mind? They change out their engines more often than some people change their underpants.
zzrmark is offline  
Old Aug 25th 2020, 8:33 pm
  #7497  
Thread Starter
 
Pulaski's Avatar
 
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,490
Pulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by zzrmark
Do you have an engine or model type in mind? They change out their engines more often than some people change their underpants.
Yeah, I know a fair bit about them, but only from the perspective of a petrolhead, so I know that models changed fequently and often multiple different engines were installed in one model during its life.

On looking at what would currently be allowed into the US, it would probably be a Griffith or a Chimaera. Four years from now the Tuscan would start to be an option.
Pulaski is offline  
Old Aug 25th 2020, 8:52 pm
  #7498  
BE Forum Addict
 
zzrmark's Avatar
 
Joined: Apr 2014
Location: Lauren's Co. SC by way of Palmetto, Florida
Posts: 3,267
zzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond reputezzrmark has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by Pulaski
Yeah, I know a fair bit about them, but only from the perspective of a petrolhead, so I know that models changed fequently and often multiple different engines were installed in one model during its life.

On looking at what would currently be allowed into the US, it would probably be a Griffith or a Chimaera. Four years from now the Tuscan would start to be an option.
Gotcha, so something that can scrape in at just 25 years old rather than an earlier 60's classic drool machine. Sorry, I can't help, just being nosy.

If you want a Walkinshaw inspired vehicle that comes in at just over 25 years why not consider a DB7?
zzrmark is offline  
Old Aug 25th 2020, 10:08 pm
  #7499  
Thread Starter
 
Pulaski's Avatar
 
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,490
Pulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond reputePulaski has a reputation beyond repute
Default Re: Let's talk about cars

Originally Posted by zzrmark
.... If you want a Walkinshaw inspired vehicle that comes in at just over 25 years why not consider a DB7?
I have/ am. Though they are available in the US.
Pulaski is offline  
Old Aug 25th 2020, 11:16 pm
  #7500  
Lost in BE Cyberspace
 
mrken30's Avatar
 
Joined: Jul 2008
Location: Portlandia Metro
Posts: 7,427
mrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond reputemrken30 has a reputation beyond repute
Default Re: Let's talk about cars

I know someone who imported a Triumph TR6 and had to jump through a few hoops. But this is a TVR US import story from pistonheads, explains some of the mechanics and headaches of importing cars.

https://www.pistonheads.com/gassing/topic.asp?t=1190002

Are TVRs classified the same as a "kit" car, from memory were they not quite often based on Fords?

Last edited by mrken30; Aug 25th 2020 at 11:19 pm.
mrken30 is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.