# Ev car with generator on board



## Bowser330 (Jun 15, 2008)

It has been thought of and it will work...

This may enlighten you a bit...
http://www.evconsultinginc.com/articles/hybridizing_dc_system.html

The problem is that generators are not light weight, even a 6kw one will weigh in at 250lbs, meaning its not really removable (unless you do a trailer design) which means you will be carrying that weight all the time...also, from the link above you see that, 6kw will only be able to support a cruising speed of about 45mph on level ground...Additionally generators are generally not that fuel efficient, I did some math on one and realized it would only give about 30mpg...good for an emergency but not that good for daily use..


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## rfhendrix (Jan 24, 2011)

If you are doing a pickup you can just put it in the bed when you need it. I have seen them at about 200lbs and $500.


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## Bowser330 (Jun 15, 2008)

rfhendrix said:


> If you are doing a pickup you can just put it in the bed when you need it. I have seen them at about 200lbs and $500.


What is the peak kw for the 200lb & 500$ genset?

I think its a great idea for emergency range extension, however I would be concerned with the efficiency of the genset if its planned to be used daily...


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## IamIan (Mar 29, 2009)

The generator is allot more complex than most people expect it to be.

To put the generator in the car you give up / trade it for over 50+ miles of pure battery range ... as the space and weight needed for the generator comes from a reduced battery size.

If you need more than ~100 miles a day often enough ... then it can be worth reducing your range to ~50 miles on battery to have the generator ... but if it doesn't happen often enough it would be better to have the generator as a detachable trailer, so you don't have to carry the dead weight all the time.

Also keep in mind ... not all generators will pass vehicle emissions testing standards in some states.


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## Bowser330 (Jun 15, 2008)

IamIan said:


> The generator is allot more complex than most people expect it to be.
> 
> To put the generator in the car you give up / trade it for over 50+ miles of pure battery range ... as the space and weight needed for the generator comes from a reduced battery size.
> 
> ...


Agreed...A genset that would be easily removable would a real asset to the EV your building...

I have seen many gensets with CARB certifications, additionally since you wouldn't be driving it primarily with the genset you could get it registered without it...and only use it for the infrequent range extending circumstances.


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## rfhendrix (Jan 24, 2011)

A quick search yielded this unit:

*http://www.harborfreight.com/engine...atts-generator-with-electric-start-98839.html*


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## rmay635703 (Oct 23, 2008)

To make a vehicle that runs like a train be remotely efficient you need a high efficiency DC generator 95+% and a high efficiency single speed motor generator turbine like the military uses 40+% efficiency.

You then would need a high efficiency charge controller to hold the genset at its optiminal power output.

Put those together and you will have something that would beat the prius hands down, sadly all of the above are very hard to find in a size that would fit into a normal car.

If you use a normal genset 80% efficiency AC generator + 80% efficiency charge + 15% efficiency motor well you get the idea. Really only good as a backup in case you go too far, not really worth driving the ev with it.

Cheers
Ryan


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## nimblemotors (Oct 1, 2010)

"beat the prius hands down" in what way? Pollution generated?

Could someone please take their generator to a smog station and get a report on the pollution it generates, and we will compare it to a Prius.



rmay635703 said:


> To make a vehicle that runs like a train be remotely efficient you need a high efficiency DC generator 95+% and a high efficiency single speed motor generator turbine like the military uses 40+% efficiency.
> 
> You then would need a high efficiency charge controller to hold the genset at its optiminal power output.
> 
> ...


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## Quso (Mar 20, 2011)

I was thinking 1200W 1.5HP or 1400 Watt 3.h.p. Generator that just charge a batteries in emergency situation the 1.5 is not that heavy soo let's say that I have quarter of batteries left I power the generator will my range extend with that small generator???


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## rfhendrix (Jan 24, 2011)

It really wouldn't be worth it. Probably less than a mile. The only thing it can help you with is you can pull over to the side of the road and wait and wait... At least you wouldn't need a tow truck though unless the highway patrol asked you, what exactly the hell are you doing?


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## rfhendrix (Jan 24, 2011)

nimblemotors said:


> "beat the prius hands down" in what way? Pollution generated?
> 
> Could someone please take their generator to a smog station and get a report on the pollution it generates, and we will compare it to a Prius.


If I am not mistaken the generator from Harbor Freight that I linked to is compliant with California standards which are pretty strict. If that particular one is not compliant I have seen a similar one that is in their store.


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## nimblemotors (Oct 1, 2010)

strict for a generator, will you please take one to a smog station,
and see what readings it gets and report back.
be sure to have it loaded down to its max capacity during the test (not idle)



rfhendrix said:


> If I am not mistaken the generator from Harbor Freight that I linked to is compliant with California standards which are pretty strict. If that particular one is not compliant I have seen a similar one that is in their store.


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## rfhendrix (Jan 24, 2011)

I don't have one but if you send the money I will buy it and do the tests for you.


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## rmay635703 (Oct 23, 2008)

nimblemotors said:


> "beat the prius hands down" in what way? Pollution generated?
> 
> Could someone please take their generator to a smog station and get a report on the pollution it generates, and we will compare it to a Prius.


The military turbine motors are more efficient than a prius and would emit less pollution per unit of power but as stated rarely come in small sizes.


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## IamIan (Mar 29, 2009)

Quso said:


> I was thinking 1200W 1.5HP or 1400 Watt 3.h.p. Generator that just charge a batteries in emergency situation the 1.5 is not that heavy soo let's say that I have quarter of batteries left I power the generator will my range extend with that small generator???


yes it will extend the range... not as much as you might think.

What is the estimated miles per kwh you are expecting to get from your completed vehicle?


For example ... if you are expecting to get 4 miles per kwh ... than a 1,400 watt = 1.4 kw generator would extend your range by about ~5 miles every hour you ran it.

If the battery is dead ... you could limp along at ~5 MPH. 

If you have a 50 mile range and drive at 50 mph in 1 hour you use the 50 mile battery and get ~5 Miles more from the ~1.4 kw generator... for a total of 55 Mile range on your battery + whatever fuel the generator consumed in that hour.

For the generator to have a significant range extending benefit you really need to get above 10kw of continuous output... from a unit that will pass vehicle emissions standards... and is small enough and light enough and cheap enough ... and even then ... it is still dead weight on short trips.


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## rmay635703 (Oct 23, 2008)

IamIan said:


> yes it will extend the range... not as much as you might think.
> 
> What is the estimated miles per kwh you are expecting to get from your completed vehicle?
> 
> ...


Actually it can have a decent effect if the car is used to actually go somewhere without a charge system and set a while. For example, you drive to the grocer and set an hour, drive to the bank set 30 minutes, etc, etc

So it depends on if he is continuously traveling or if he is going from errand to errand and the car has a chance to sit a bit.


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## EV-propulsion.com (Jun 1, 2009)

Keep in mind if anyone plans to use a generator with a charger, a lot of generators are modified sine wave AC output. Depending on the charger design (it may need to see the peaks of the sine wave which you don't have with modified sw), this may not charge to the correct voltage. So either get a true sine wave generator or check with the charger manufacturer first.
Mike
www.EV-propulsion.com


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## IamIan (Mar 29, 2009)

rmay635703 said:


> Actually it can have a decent effect if the car is used to actually go somewhere without a charge system and set a while. For example, you drive to the grocer and set an hour, drive to the bank set 30 minutes, etc, etc
> 
> So it depends on if he is continuously traveling or if he is going from errand to errand and the car has a chance to sit a bit.


Agreed.

It could also be used to charge while at work for 8 hours if their is no charge plug available ... In 8 hours the 1.4 kw generator could provide up to ~11 kwh of electricity ... at ~80% net efficiency between charger and battery cycle you would get ~9 kwh of usable battery charging ... if the converted vehicle averages ~4 miles per kwh that would be ~35 Miles restored while working for 8 hours.


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## Quso (Mar 20, 2011)

Thx guy for your helP and support


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## crap (Dec 5, 2009)

Just grab a BLDC of apropriate size and add a rectifier. Connect the shaft to a boat engine of matching power and the output cables to the battery. Add fuses, overvoltage cutoff and possibly a rev limiter for good measure. There ya go, a hybrid!

Why a boat engine? Doesn't have to be, but boat engines are normally designed for a higher continous load in relation to its size than those from wheeled vehicles. 
For a generator I would suggest a mars/etek bldc/pmdc, or just make your own (check out DIY windpower sites for directions).


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## lkcl (Sep 16, 2011)

Bowser330 said:


> It has been thought of and it will work...
> 
> This may enlighten you a bit...
> http://www.evconsultinginc.com/articles/hybridizing_dc_system.html
> ...


can i please see the calculations? you can see what i've put together, here:
http://lkcl.net/hybrid_electric_vehicle/design_principle.html

i've found something called the SMDO 4000 (yes it's listed as an "export" generator) which is only about 100kg, and it runs for 4.8 hours, consuming 4.3 litres (1 gallon).

in a light-weight vehicle (about 550kg) you can ignore rolling-resistance (but ONLY with the new "Low Rolling Resistance" Tyres!) and that just leaves aerodynamic drag to deal with.

so, using the wikipedia page for "Drag Physics" - http://en.wikipedia.org/wiki/Drag_%28physics%29#Power

you can back-calculate from any Generator to the maximum top speed in mph, with this equation:

CubicRoot ( GeneratorPower (W) * Efficiency (%) * 2 / ( 1.184 * DragCoefficient * FrontalArea (sq.m) ) * 2.237

so, take a 4kW generator, assume a 75% efficient drivetrain, assume a drag coefficient of 0.3, and a frontal area of a small vehicle as 1.5sqm, and you get a top speed of 51mph.

nothing _like_ the 30mph posted on the link above. however, if you have a truly dreadful set of standard road tyres and you have a 1 tonne or 2 tonne vehicle, then yes, i can well believe that the figure would be 30mph, because you'd lose about 2HP @ 30mph just to rolling resistance alone, and that goes up to NINE HP @ 55mph for a 4000lb (1814kg) vehicle:

http://www.howstuffworks.com/tire4.htm

ok i just realised i made a mistake on my article, which i'll correct: i thought the LRR tyres were 25x better, they're actually only 2.5x better 

so, that means you lose.... 700 watts (not 70!) for rolling resistance @ 55mph for a 500kg vehicle... which is significant. so, subtract that, and.... i *still* get a figure of 47mph!

$ python
>>> pow(3300*.75*2/(1.184*0.3*1.5),1/3.0)*2.237
47.026895730096257

so - i'm not getting it. i'm not seeing 30mph, i'm seeing 47mph (for a 500kg vehicle). where does this 30mph come from?

and, even if that 30mph figure is correct, that's still 30mph * 5 hours = 150mpg. what is going on here??


l.


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