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  #121  
Old 09-25-2011, 10:00 PM
gor gor is offline
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Default Re: Why are there no on board generators?

hybrids should have been plug-ins from the beginning - fuel economy would have been obvious - when prices on gas jumped twice, (and will do it again, matter only of when) people could make short trips without single drop of gas
well, to extend range at highway speed we need or twice bigger battery (to cover losses in controller, motor, drivetrain, etc); or genny to compensate resistance and losses or engine

below spreadsheet -
resistance for 250cc kawi ninja250r at 57mph: air drag - 4.8hp (3.6kw) ; total (+ rolling+very small 0.06degr.grade - 6.5hp (4.8kw) without drivetrain losses (5-10%) (in dyno data - power at wheels, drivetrain losses included)

for 4.8kw resistance at 57mph:
battery necessary:
- to cover controller, motor, drivetrain, extra (wires, etc) efficiency losses: (10+15+5+1=31%); batt should be 145% -7kw;
at36% losses - batt. 156% - 7.5kw;
at41%(15+15+10+1)- batt: 165%=8kw;
at46% - 185%=9kw and
at50%combined losses - twice the battery (~10kw)

7-10kw/h lithium at 100wh/kg, 70-100 kg for 1h at 57mph
250cc eng. - 12kw, 43kg (with transmission) - for x hours

so, i would say - drop all the efficiency losses above, drop the geny also, leave the ice
p.s. since engine for maintaining steady speed and el.drivetrain - fo raccel., i'm sure we can get away even with smaller lighter engine & trany.
who have data on engines and tranys (from donor bikes - weight, power,etc) - please, share
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File Type: jpg kaw.250ninja.power.torque.resist.JPG (82.8 KB, 6 views)
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File Type: zip Kawasaki Ninja 250R_.zip (189.2 KB, 0 views)

Last edited by gor; 09-25-2011 at 10:15 PM.
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  #122  
Old 09-25-2011, 10:05 PM
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EVfun EVfun is offline
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Default Re: Why are there no on board generators?

The first generation Prius has an electric range of about 6 miles with a top electric only speed of 42 mph. The Honda Insight couldn't even operate electric only because the motor was the engine's flywheel.

On the plus side, if you ran your Prius out of gas you could still limp to the nearest gas station. I did it a couple of times. The old Dodge Dart couldn't manage that stunt.
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  #123  
Old 09-26-2011, 11:36 AM
Bowser330 Bowser330 is offline
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Default Re: Why are there no on board generators?

What do you gents think about this setup for a range extender:

3cyl G10 engine found in the Geo Metro or Suzuki Swift
80hp (peak), 175lbs, ~1000$

Agni 95 Motor found here
30hp (peak) 21hp (cont.), 24lbs, ~1600$

I found mpg data and dynos of the G10 1.0L 3cyl engines and found that in generator form it is likely to achieve ~50mpg & ~25hp @ 2500rpm

Summary:

2,600$
16kw continuous
~200lbs
>22 miles+

vs.

2,600$
8.3kwh (1$/ahr, 2600*3.2V)
~ 200lbs
22 Miles+ @ 80% DoD & 300wh/mile assumption

Last edited by Bowser330; 09-26-2011 at 11:40 AM.
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  #124  
Old 09-26-2011, 03:38 PM
Anaerin Anaerin is offline
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Default Re: Why are there no on board generators?

You know, I'm fairly sure it'd be quite easy to take a Mazda wankel engine or an old Comotor one, and couple it to an APU alternator, for a small, light, and efficient range extender. Reasonably cheap, too. And, given the very high speeds wankel engines are good to (9,000-10,000 RPM) as opposed to the lower speeds on piston engines (5,500-6,500 RPM) they would be better for direct driving an alternator or generator. Couple that with a nice high-speed-capable 5-speed transmission to run your car from, and you have a nice slice of your conversion done.
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  #125  
Old 09-26-2011, 03:50 PM
Bowser330 Bowser330 is offline
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Default Re: Why are there no on board generators?

Right, Wankels are small and light, however I wasn't sure how efficient they are...i'm concerned with efficiency, as I don't want to pollute too much, but I am more concerned with the weight of the APU.

Can you tell me what APU alternator you are talking about that's cheaper and can generate 30hp like the Agni_95?
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  #126  
Old 10-10-2011, 09:26 AM
lkcl lkcl is offline
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Default The new Volkswagon XL1: on-board "generator"

the new VW XL1 has a maximum fuel economy figure of 430mpg, and a combined mpg figure of 313mpg.

it's achieved through an 800cc TDI two-cylinder diesel engine, connected in parallel to an electric motor (i.e. it's a "Parallel Hybrid", not Series-Hybrid), and has a *seven* speed gearbox.

the vehicle's weight is 795kg, is made of a carbon-fibre resin body on top of a steel/iron chassis, and uses *magnesium* alloy wheels, for lightness.

the drag coefficient is a stunning 0.186, which beats the GM EV1. the styling looks near-identical to that of the EV1 (and the Honda equivalent). there seems to be something about this rather boring but near-teardrop-shaped profile that attracts engineers, probably because of its simplicity.

anyway: the fact that the two motors are in parallel (on separate clutches) means that yes, effectively, this vehicle has an on-board "generator".

one way in which some significant efficiency will have been achieved will be to use a planetary gearbox (same as in automatics, but without the torque converter).

but, overall, this vehicle just emphasises that yes, getting good drivetrain efficiency, low weight, and low Rolling Resistance and drag coefficients are all absolutely absolutely essential, yet if that's done, then yes you can get staggeringly good fuel economy figures.
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  #127  
Old 10-10-2011, 09:32 AM
lkcl lkcl is offline
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Default Re: Why are there no on board generators?

Quote:
Originally Posted by Bowser330 View Post
What do you gents think about this setup for a range extender:

3cyl G10 engine found in the Geo Metro or Suzuki Swift
80hp (peak), 175lbs, ~1000$

Agni 95 Motor found here
30hp (peak) 21hp (cont.), 24lbs, ~1600$
the Agni's good, bowser, but the engine's far too heavy. it somewhat defeats the object of the exercise.

agni... agni... oh you mean a Lynch LEMCO motor? yes, they're bloody excellent. superb torque, very low weight, high efficiency.

oh wait... Lynch Motors are DC output, and it's a brushed motor. so, you can't get AC out of it, and you'll get massively-spiked intermittent output as it arcs when the commutators turn. so you'd need to include some rather heavy-duty spike supressors (inductors) that....

yeah, you'd be better off finding a BLDC motor from somewhere.

sorry, bowser, perhaps not what you were expecting to hear: no good, and no good

l.
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  #128  
Old 10-10-2011, 10:01 AM
lkcl lkcl is offline
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Default Re: Why are there no on board generators?

Quote:
Originally Posted by Anaerin View Post
You know, I'm fairly sure it'd be quite easy to take a Mazda wankel engine or an old Comotor one, and couple it to an APU alternator, for a small, light, and efficient range extender. Reasonably cheap, too. And, given the very high speeds wankel engines are good to (9,000-10,000 RPM) as opposed to the lower speeds on piston engines (5,500-6,500 RPM) they would be better for direct driving an alternator or generator.
i'd be very concerned about running a large electric motor at those kinds of RPM (unless geared down, but again, you lose efficiency by doing so). any large electric motor has to have, by definition, a considerable diameter. you start running that much metal round at 10,000 RPM and you're pretty much guaranteed to have bits flying off.

diesel engines are really the sensible option, because of the enormous torque that they can achieve, even at low RPM.

[update: i just found this fascinating article - http://www.libralato.co.uk/pa_comparison.html which mentions several instances where wankel engines have been used in concept cars. so, looks like you were right - it can be done!]

l.

Last edited by lkcl; 10-11-2011 at 10:19 AM. Reason: found link to libralato engine
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  #129  
Old 10-11-2011, 10:51 AM
lkcl lkcl is offline
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Default Re: Why are there no on board generators?

Quote:
Originally Posted by gor View Post

to cover controller, motor, drivetrain, extra (wires, etc) efficiency losses: (10+15+5+1=31%); batt should be 145% -7kw;

at36% losses - batt. 156% - 7.5kw;
at41%(15+15+10+1)- batt: 165%=8kw;
at46% - 185%=9kw and
at50%combined losses - twice the battery (~10kw)
http://www.fueleconomy.gov/feg/atv.shtml
drivetrain efficiency of ICE vehicles is between 93 and 95% efficient.

motor controllers are about 98% efficient.

motors are about 90% if you get a standard BLDC and 94% if you get an EMRAX or a Printed Motor Works Ltd "Outrunner".

also, you don't *add* the numbers together, you *multiply* them.

wires: if you get half-inch-thick cables, losses are such that you just... get thicker wire!
http://www.stealth316.com/2-wire-resistance.htm

so if you use 10mm thick cable, the voltage drop is 0.14v: as a ratio of 100v that's negligable and can be ... well, let's not discount it - it's 0.0146%...

so... worst-case figures: .998 * .93 * .9 * .93 = .819 ooooo jammy basturd, that's *just* within that 80% target but if you use the EMRAX motor, you get 0.855 which is 85.5% drivetrain efficiency. best case: 0.998 *.98 * .94 * .94 = .864: 86.5% drivetrain efficiency.

that's excluding efficiency losses from the generator itself, but again, that's been taken into account already by using the "rated" figures (power of the generator, not power of the motor *running* the generator).

l.
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  #130  
Old 10-12-2011, 06:58 PM
Bowser330 Bowser330 is offline
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Default Re: Why are there no on board generators?

Quote:
Originally Posted by lkcl View Post
the Agni's good, bowser, but the engine's far too heavy. it somewhat defeats the object of the exercise.

agni... agni... oh you mean a Lynch LEMCO motor? yes, they're bloody excellent. superb torque, very low weight, high efficiency.

oh wait... Lynch Motors are DC output, and it's a brushed motor. so, you can't get AC out of it, and you'll get massively-spiked intermittent output as it arcs when the commutators turn. so you'd need to include some rather heavy-duty spike supressors (inductors) that....

yeah, you'd be better off finding a BLDC motor from somewhere.

sorry, bowser, perhaps not what you were expecting to hear: no good, and no good

l.
I am not sure I agree, I dont think 200lbs is much weight at all, did you consider the second part of my post that you did not quote? I dont see how the weight defeats the purpose when the weight of a comparable portion of lithium ion batteries doesn't give you but 22 extra miles, where as the range extender could provide 16kw continuously...

2,600$ from the genset concept
16kw continuous
~200lbs
greater than 22 fuel powered miles

vs.

2,600$ of lithium-ion batteries
8.3kwh (1$/ahr, 2600*3.2V)
~ 200lbs
22 Miles @ 80% DoD & 300wh/mile assumption

Last edited by Bowser330; 10-12-2011 at 07:08 PM.
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