LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently Fri Nov 28, 2014 6:46 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 47 posts ]  Go to page Previous  1, 2, 3, 4  Next
Author Message
PostPosted: Tue Oct 26, 2010 12:02 am 
Offline

Joined: Wed Nov 25, 2009 8:47 am
Posts: 139
Location: Tecumseh, Ontario Canada
If I'm reading you right, 200 miles of performance driving on 15 minutes of charging, I'd have to say we're not there, not by a long shot.

It's quite feasible to build a really spectacularly quick EV drag racer. Or, juggling similar components, an energy stretching city car with acceptable road manners and usable range. I don't think we're at the stage where both are possible from the same vehicle.

The true math is beyond me, but guesstimating that spirited driving will use ~35 hp, with average speeds around 70 mph, it'll take about 3 hours to travel your 200 miles. Each HP is ~ 750W, so you'll consume 750x35x3/1000 = 78.75 kWh

Then you have to stuff that back in with your nuclear-lightning powered charger in 0.25 hours

78.75/.25 = 315 kW (for comparison an average 120v 15A household circuit puts out about 1.8 kW)

And this doesn't take any losses in to effect -- the losses express themselves by heating your battery pack to roughly the surface temperature of the sun while charging and discharging, so...

Even with supercapacitors replacing your batteries (which should get us closer to the quick time scale charging scenario) we're talking about really spectacularly large amounts of energy transfer over short times.

I bet you could build a really cool EV Locost, but you'd have to compromise either performance or range.

Cheers, Ted


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 12:19 am 
Offline
Mid-Engined Maniac

Joined: Sun Apr 23, 2006 8:26 pm
Posts: 4892
Location: SoCal
Your math is close enough to prove the point. It's HUGE amounts of power, but the general public is untroubled by such matters as physics - they just want it to happen. The dumb media doesn't want to rain on the happy shiny parade, so lets the illusion continue.

The other issue that no one's addressing is where all that power's going to come from. Every summer here in SoCal we receive warnings from the local power companies that if we don't cut back all non-essential power, we'll have blackouts. Okay, now add millions of charging electric cars onto the grid and see what happens. Of course, people always say it won't be a problem because "we'll charge them during off-peak hours." Really, when you used over half your charge to get to work, you're not going to charge it? Think again. And, when the blackouts do happen, how do you get home? But that's okay, it'll all be fine... somehow.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 12:40 am 
Offline
User avatar

Joined: Sat Sep 26, 2009 8:25 pm
Posts: 879
Location: Park Hills, KY
Not to argue against you, but demographic makes all the difference in the world.... The OP is from Cleveland, and if it's any thing like Cincinnati, blackouts aren't an issue. Building this "on the cheap", don't expect to fully charge in less than 5 hours... and don't expect more than 70-100 miles range on a good day with a tempered hoof... If you really want make some mileage, invest a little cash into one of Jack's Lola kits to clean up the aero, cover the wheel openings...

Mileage wise, it's no different than driving an ICE... balls to the wall, expect to burn more fuel, [kitty cat] foot it and get a little further.

If it's not your daily driver, how much does it matter? It's your toy... Yeah, you'd like to hit the autocross and last the entire day without running out of juice... bring a generator and hook it up between heats/sessions. The original tZero had an optional generator trailer that would kick in when the batteries dropped to a certain voltage... Again, I'm at work, so this is a possibly wrong quote, but I want to say close to 500 miles with the generator hooked up.

I know the "don't expect" lines sound dooming... That 70-100 miles a day should cost less than a few dollars a month on your bill...


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 12:41 am 
Offline
User avatar

Joined: Sat Sep 26, 2009 8:25 pm
Posts: 879
Location: Park Hills, KY
[kitty cat]? awesome....!


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 1:15 am 
Offline

Joined: Wed May 27, 2009 1:13 pm
Posts: 257
Location: cleveland, ohio
krepus wrote:
[kitty cat]? awesome....!

:shock:
no clue what this means.

As for cost it can be done cheaper than ac propulsion at 10k and 10k of batteries. not much easier i doubt. but i.ll play with all the links and stuff you guys have given.

as for 15min charge that didnt come out right. i meant with it like this.
with a onboard generator EV, charge batteries when at home with 110v outlet. leave the house with onboard generator(OG, not original gansta) running. lets say the ac motor averages useage of 100kw/hour at 50mph and OG makes 90kw/hour. eventually the batteries will be low bc the OG isnt charging fast enough. figure for 200 miles would need 400kw of straight battery but the generator would average that down to 40kw. use more than enough battery and it might never need plugged in. so figure stop for 15 and let the OG catch back up on charging. not 100% maybe but some. now of course this is all bad math and numbers but i dont mean for an OG to only b used at stops for breif periods but maybe need to stop to let it charge without discharging at same time, basically play catch up.

all these number i'm just puling out of thin air. no clue what average electric motor uses or what average generator puts out. just saying thats the general idea. maybe at this point in time batteries are too expensive and too heavy to make this feasible in anything expect a S-10 sized pick up and thats too hard to make that much performance from(kind of, compared to a 7).
this is why i posted it in "In Theory It Could Work" section. i understand mechanical stuff quite well but i'm not an electronics knowledge guy(not yet i gues i should say) so maybe someone with that knowledge could make it cheaper.

hopefully they'll find this and improve all our ideas.

_________________
86 rx7 as my dd
90 talon as old dd turned into donor for the locost
06 suzuki sv1ks for the kneedragging fix

mitsu 4g63 powered 442e - viewtopic.php?f=35&t=7317&start=0


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 1:28 am 
Offline
User avatar

Joined: Sat Sep 26, 2009 8:25 pm
Posts: 879
Location: Park Hills, KY
[kitty cat] is forum friendly for the "p" word for cat... i originally said that if you p u s s y foot(driving gently, gingerly, cat-on-a-fence-like) that you could get higher mpc(miles per charge)

Here is the original tZero with the dry cell batteries and the charging trailer


Attachments:
Acp_tzero_dsc00309.jpg
Acp_tzero_dsc00309.jpg [ 143.31 KiB | Viewed 717 times ]
Acp_tzero_DSC00467.jpg
Acp_tzero_DSC00467.jpg [ 155.96 KiB | Viewed 717 times ]
Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 3:38 am 
Offline
User avatar

Joined: Mon Apr 12, 2010 5:40 pm
Posts: 1894
Location: san francisco bay area
76 bucks a pop for these 3kfarad pieces works out to $7300 for 2 banks at 120 volts.
294 amp max continous output at 20c rise 4300 amp 1 second burst and a touch over 6 wh.
short circuit 18600 amp possible :shock: then theres the controller...
http://www.maxwell.com/ultracapacitors/datasheets/DATASHEET_K2_SERIES_1015370.pdf

_________________
"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 4:07 am 
Offline
User avatar

Joined: Mon Apr 12, 2010 5:40 pm
Posts: 1894
Location: san francisco bay area
i knew i had seen a price for these before http://www.rell.com/Pages/Product-Details.aspx?productId=900902

_________________
"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 4:18 am 
Offline
User avatar

Joined: Wed Nov 12, 2008 6:29 am
Posts: 3406
oldejack wrote:
speaking only as a proof of concept vehicle mind you. ..
what if you used the electric propulsion motor and cvt from a prius without a directly connected gas motor?


I have never seen or tinkered with a Prius but I believe the "CVT" isn't a CVT but a CV mechanism of which I know about but don't know the name of (or how to easily explain it) that relies on both the input of the electric motor and the petrol motor to determine the overall gearing - you can not delete one of them.

I'll find some info on the system later.


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 4:32 am 
Offline
User avatar

Joined: Wed Nov 12, 2008 6:29 am
Posts: 3406
Oh and by the way, research flow batteries for fun - they are the answer, pop into a petrol station and simply change the fluid because 5 minutes is certainly better than 8 hours of charging (The petrol station reactivates the fluid).

Vanadium redox batteries are also what they are called. A German University has just apparently discovered a new fluid scheme that makes them superior to lithium batteries where as uptill now they have been about 4 times bulkier which is no good for cars.


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 6:13 pm 
Offline

Joined: Thu Sep 10, 2009 6:25 am
Posts: 37
LOL on the EV towing an ICE to charge the battery. palaver and nonsense. It ain't cheap, and it ain't even good, and I still say what's the point. Until the batteries get lighter and allow more storage... just make sure you are peeing down-wind so you don't get any on you.

it really isn't the same as a lowcost 7 since what people are doing is building something high performance for less money, not more money. The performance is better than a 'regular' car. It's doubtful you will get to the same performance anywhere near an ICE since just the battery weight alone will make it handle worse. Even as a theoretical exercise you could trade everything -- including range and get close for 6-10 laps around the track at which point the car would peter out.

I was all excited about the possibility of building an EV commuter myself, until I did some research -- man was I disappointed. Everything was so expensive, and the performance (generally) and range was completely crap -- I soon dropped the whole idea -- it's just not ready for prime time


Top
 Profile  
 
PostPosted: Tue Oct 26, 2010 11:52 pm 
Offline

Joined: Wed May 27, 2009 1:13 pm
Posts: 257
Location: cleveland, ohio
Without some really good base knowledge and great scaveging abilities there won't be a comparably performing Locost in terms of cost for a while. I unfortunetly don't have the electrical knowledge right now nor the natural scavenging ability some do.

As far as actual performance I believe a person could build a EV7 for less than twice of what some of the less thrifty locosts are. I know SteyrTMP with just a miata based 7 is approaching $5000 budget and that's with turning into a cheap a$$ half way through. A locost could easily turn into $10k project. To get a equivalant of 120hp 1300lb car from a EV under $20k is very doable.

As for me doing it I'm in for a under $1000 right now and can probably finish with maybe only 1500 more and that's before parting out what's left of donor. So I'm not building an EV that'll keep up with a 250+hp 1800lb Locost that I'll have when done for the same price. But I had the knowledge and a lot of free parts for an ICE that I wouldn't of of an EV.

Of course by the time I'm finish one and decide to go for 2 the tech for an EV might have gotten much cheaper and myself a lot smarter. Let's hope at least :)

_________________
86 rx7 as my dd
90 talon as old dd turned into donor for the locost
06 suzuki sv1ks for the kneedragging fix

mitsu 4g63 powered 442e - viewtopic.php?f=35&t=7317&start=0


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 5:27 am 
Offline
User avatar

Joined: Sat Sep 26, 2009 8:25 pm
Posts: 879
Location: Park Hills, KY
I was about to make a witty comment about how great it is to have all the research time and experimental time before we get our builds started, when I was reminded of a slightly different, equally witty comment regarding time... It makes fools of us all...

I honestly think an EV7 could be built for less than $7k... Do I have $7k to prove it...? no, but I wish to hell I did! Granted, an EV cost more up front, less down the line... but I digress...

So I guess for now, we'll stick with Kuboto td's....


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 10:53 am 
Offline

Joined: Wed May 27, 2009 1:13 pm
Posts: 257
Location: cleveland, ohio
for efficency the kubota td but for performance I'm still eyeing up an all aluminium chevy LS v8. That's just me though. I bet I could milk it for 50mpg at 70mph. Close to jack's kubota considering the power difference

_________________
86 rx7 as my dd
90 talon as old dd turned into donor for the locost
06 suzuki sv1ks for the kneedragging fix

mitsu 4g63 powered 442e - viewtopic.php?f=35&t=7317&start=0


Top
 Profile  
 
PostPosted: Wed Oct 27, 2010 10:30 pm 
Offline
User avatar

Joined: Sat Sep 26, 2009 8:25 pm
Posts: 879
Location: Park Hills, KY
Variable displacement or an un-altered small block from a 79 z28(140 horsepower...)? You better have some tall gears...lol! Dude, if you got 30mpgs, I'd be impressed! :cheers:

Just to toss this out there...

Siemens and a few other companies have what is called a hub motor. Now, a hub motor is nothing new really, but they're building them with the torque capacity to move a full size car... The motor is kind of flat, a bit disc-ish... It bolts up directly behind the wheel, eliminating the need for individual drive train parts... no transmission, no rear end... and true independent suspension. Braking is taken care of by the motor itself. Mini has an all wheel drive(4 individual motors, one at each wheel) version and there's another whose name escapes me at the moment, with 200 hp at each wheel... Imagine the possibilities and level of control...


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 47 posts ]  Go to page Previous  1, 2, 3, 4  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY