small trailer with generator

13153 Views 40 Replies 11 Participants Last post by michaeljayclark, Feb 28, 2011

OMT

Discussion Starter · Feb 9, 2011

i wasnt sure were to put this, but i found a 6kw gas generator for 300$ locally. im not planning on buying it, or doing this any time soon, but it got me thinking( i know im not the first one) to lets say convert a car on lead to go 60miles and lets say at 65mph it takes 12kw to sustain the speed.

if i made a small, aurodynamic trailer, which held the 6kw generator, and the gas tank would it roughly double the range because the generator is providing half the power needed to keep the car moving?

PS: this is assuming i magically found a 6kw charger( doubt it)

is the only other way to run the generator directly into the controller to somehow modiy it so it outputs 144v DC?

the reason i posted this is because i think it would be extremely practicle if i had an ev that went 60 miles, and i had a small trailer at home that whenever i decide to go to another city i can just plug in and attach it.

1 - 20 of 41 Posts

michaeljayclark

· #2 · Feb 9, 2011

great idea and yes has been in discussion many times.

I am planning the same idea however my generator will be onboard. I want my EV to be a backup generator for my house, a generator for camping or other type of trips, and to also help anyone else with an EV. Ill be the first in Tampa Bay to be a rescue road service. Ill be able to come to you if noone will be kind enough to let you plug in. The genset i am using is 15000 watts AC with a 50 amp 240 outlet.

The volt has an onboard generator, a 110 KW AC. enough to run the car just on the generator but sadly they claim not enough to run the car and charge up the batteries which I kind of dont understand why with that much power. At times when the car isnt accelerating hard or traveling on the highway it cannot be drawing more than 100 amps. that generator can produce at least 300 amps so why cant they sent some power back into the batteries?

not trying to hijack your thread...

so year a generator on a trailer is a great idea. I have even heard of an EVer that got a 100 kw diesel generator and towed it behind him when he needed to go on long trips.

I think the whole idea is frowned upon because we are running an ev that is supposed to be completely emission free when recharged by solar panels and then run it by proxy on a gasoline or diesel engine.

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algea07

· #3 · Feb 9, 2011 (Edited)

yes many people have had this idea, myself included. my idea is similar to yours but instead of using the ac to charge the battery, you get a three phase ac generator and use a three phase ac to dc rectifier.

generator: its 90kg and will put out half the power you'll need. with some creative engineering you should be able to cut the weight down and, fit under the hood (you'll probably have to put some batteries in the boot though)

Rectifier: this should put out enough grunt to keep the car moving.

i think the ac voltage rectified to dc is 273v, so if you build you pack to suit that voltage (roughly 75 cells) then you should be able to pump the volts from the generator into the battery pack. EDIT: i may have gotten the dc voltage wrong i'd suggest doing some more of your own research and talking to an electrical engineer.

the only thing left to consider is will this damage your batteries, can you just pump a constant voltage into the batteries to charge them.

I've asked that question on this forum

best of luck

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michaeljayclark

· #4 · Feb 9, 2011

found this in wikipedia under rectifier:

For single-phase AC, if the transformer is center-tapped, then two diodes back-to-back (i.e. anodes-to-anode or cathode-to-cathode) can form a full-wave rectifier.

While half-wave and full-wave rectification suffice to deliver a form of DC output, neither produces constant-voltage DC. In order to produce steady DC from a rectified AC supply, a smoothing circuit or filter is required.[2] In its simplest form this can be just a reservoir capacitor or smoothing capacitor, placed at the DC output of the rectifier. There will still remain an amount of AC ripple voltage where the voltage is not completely smoothed.

not sure is this can be done with a 15000 watt single phase ac generator BUT would be nice if possible:

The simple half wave rectifier can be built in two versions with the diode pointing in opposite directions, one version connects the negative terminal of the output direct to the AC supply and the other connects the positive terminal of the output direct to the AC supply. By combining both of these with separate output smoothing it is possible to get an output voltage of nearly double the peak AC input voltage. This also provides a tap in the middle, which allows use of such a circuit as a split rail supply.

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m38mike

· #5 · Feb 9, 2011

OMT said:
if i made a small, aurodynamic trailer, which held the 6kw generator, and the gas tank would it roughly double the range because the generator is providing half the power needed to keep the car moving?

is the only other way to run the generator directly into the controller to somehow modiy it so it outputs 144v DC?

the reason i posted this is because i think it would be extremely practicle if i had an ev that went 60 miles, and i had a small trailer at home that whenever i decide to go to another city i can just plug in and attach it.

The answer to your first question is "it depends." What is the terrain like? how light or heavy is your EV? How much power does it take to travel at speed? I'm working through those very issues right now. I'm building a gen-trailer so I can keep my EV moving over long distances.

I don't think you want to run your generator directly into the controller. Like was mentioned above, most generators produce AC power that needs to be smoothed so it doesn't damage the controller. Running through a bridge rectifier will get it to a bumpy DC. Running it through a smoothing diode, or into a battery pack will take the rest of the bumps out.

Your "practical idea" is why I'm building my trailer. That and an adventure driving my EV to Alaska and back, just because I can. Check out the "generator trailer to power EV" thread for lots of discussion on different ways to power the EV.

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michaeljayclark

· #6 · Feb 9, 2011

I found a 33000 watt single phase ac bridge rectifier on ebay for $65. ill be opnly using 15000 watts so this bridge rectifier shouldnt have any problems.

a member of our association, jim parish, is designing a device that will charge control the generator so it doesnt overcharge the battery pack. If the battery pack is 144 volts the generator will stay off until the voltage drops below 144 volts. the generator will kick on until the pack gets back to 144 volts then turn off.

of course the generator has to have an electric start to work in this set up.

he can also put together a device that will simply have a contactor that is closed when the 144 volt pack is below 144 volts and then open up when the pack is at 144 volts, the genset would be running and not shut off, this would be for generators that do not have electric start.

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nimblemotors

· #7 · Feb 10, 2011

This is a common idea, and it has a lot of complications that are not obvious on the surface, but some people have done it with an onboard generators.
You really want the gas motor to drive the wheels directly,
as the Volt was updated to do instead of a serial generator, otherwise your MPG is pretty bad. Some have built "pusher trailers" that have a gas motor with driven wheels that pushes the EV on the highway.

I say just rent a car for a longer trip. Heck of a lot easier and probably cheaper if its not often. If its often, get a Prius...

OMT said:
i wasnt sure were to put this, but i found a 6kw gas generator for 300$ locally. im not planning on buying it, or doing this any time soon, but it got me thinking( i know im not the first one) to lets say convert a car on lead to go 60miles and lets say at 65mph it takes 12kw to sustain the speed.

if i made a small, aurodynamic trailer, which held the 6kw generator, and the gas tank would it roughly double the range because the generator is providing half the power needed to keep the car moving?

PS: this is assuming i magically found a 6kw charger( doubt it)

is the only other way to run the generator directly into the controller to somehow modiy it so it outputs 144v DC?

the reason i posted this is because i think it would be extremely practicle if i had an ev that went 60 miles, and i had a small trailer at home that whenever i decide to go to another city i can just plug in and attach it.

michaeljayclark

· #8 · Feb 10, 2011

paid 1000 for a generator that will extend me to as far as I want to go. that is way cheaper than renting a car!

I also have a backup generator for my house...

I can charge other EVs that need help on the road

I have a generator for events, camping, etc..

I have one car, not a commuter car and a second car.

those are my reasons for having an onboard generator.

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cyclops2

· #9 · Feb 13, 2011

Michael makes a very real world reason for the generator. $ 1,000 does not buy to many long distance trips in auto rental costs.

The safest way for the generator to run, is to connect it thru a breaker or fuse to the battery. The battery will smooth out a lot of the voltage spikes that can be generated during any emergency. The battery buys the drive controller some precious time to start clamping the dangerous spikes or deciding to go off line completly, if the generator starts climbing up in output voltage for any reason. Undesireable conditions do happen.

Lightning strike 6' away from the car is a real bad one. All bets are off if that should happen.

Bellistner

· #10 · Feb 13, 2011

While wandering the back yard over the last few days, I 're-spotted' the old Diesel trailer that was used in the earthmoving business. It's a 'shorty' trailer, being both narrower and shorter than a 6*4 box trailer. The tank is simply dropped on top of the rail and welded on.

I expect that to convert it to a genset trailer would be quite simple: grind off the welds and lift the tank off, weld motor mounts/adaptor onto the frame, seat and secure the old ICE out of your donor car.

If you wanted, you could equip the trailer with more batteries for a range extension before firing up the genset.

If you use an ICE out of a car, you get a fairly efficient heat engine, plus it comes with all the required emissions control, so will probably be cleaner than a little Honda genset or similar.

I reckon that when we get the yard cleaned up (I've got a bug up my arse about it at the moment, and I've done well over the last week), I'll pull it off its resting place and have a better look at it.

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cyclops2

· #11 · Feb 13, 2011

You make a great point about a ICE versus any other power. Gasoline is everywhere & cheaper. Repairing a car ICE is very easy on a long trip. Compared to a diesel.

Good logic.

Not to sure about lugging outside batteries. I would simply plan my generator recharges while doing meals or a longer rest stop. That REALLY reduces the generator size. VERY quiet muffler does allow for recharges at night anywhere. People accept motor homes running at night.

nimblemotors

· #12 · Feb 13, 2011

Generators are very dirty engines,
probably 100 times more pollution than a rental car.
And then you'll get 20 mpg, not 40 mpg or 50 mpg because of its inefficiencies.

So great, it is cheap and convienent, but you are now a gross polluter,
and probably illegal as well.

cyclops2 said:
Michael makes a very real world reason for the generator. $ 1,000 does not buy to many long distance trips in auto rental costs.

The safest way for the generator to run, is to connect it thru a breaker or fuse to the battery. The battery will smooth out a lot of the voltage spikes that can be generated during any emergency. The battery buys the drive controller some precious time to start clamping the dangerous spikes or deciding to go off line completly, if the generator starts climbing up in output voltage for any reason. Undesireable conditions do happen.

Lightning strike 6' away from the car is a real bad one. All bets are off if that should happen.

michaeljayclark

· #13 · Feb 14, 2011

newer generators are carb and epa certified. a quick search on generac epa certified shows a lawsuit LOL from the EPA against generac for engines that do not meet the clean air act. looks like prior to 2007

so Id say generators are now not as clean as cars BUT not as dirty as they were before. generators in the past were extremely dirty, especially ones that were 2 stroke and you mixed oil into the gas.

the generator I have is carb and epa certified.

I just believe that EVs with a EV mode and a series hybrid mode will win out overall as the stepping stone to EVs until lithium battery prices drop below 200 dollars per kilowatt hour.

cyclops2

· #14 · Feb 14, 2011

How dirty is a DIY 15 KW generator powered by a Honda 4 or V6 complete with fuel tank & muffler system ?

Bellistner

· #15 · Feb 14, 2011

cyclops2 said:
How dirty is a DIY 15 KW generator powered by a Honda 4 or V6 complete with fuel tank & muffler system ?

A 4 or 6 out of a car? Well, assuming you keep all the EmCon equipment, it'll be as dirty as it was in the car, with the exception that since it's not directly powering the wheels, you can run it at a constant RPM wherever it's most efficient.

If you've got a Genset dedicated to a particular car (or cars), you could even integrate controls inside the cabin for remote start, throttle, etc. Cover the motor with a shroud for aerodynamics and have a PIC-driven servomotor to open and close a slot in the shroud for cooling, and you're laughing.

If you're not going long distances regularly, but do occasionally (for example, my partner usually travels less than 10km/day, but occasionally has a need to go 200km in one hit), a GenSet trailer is probably the way to go. If you do cover long distances often, a Hybrid (or ER-EV) is probably a better bet.

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michaeljayclark

· #16 · Feb 14, 2011

search fueleconomy.gov

http://www.fueleconomy.gov/feg/bymake/bymanuNF.shtml

Honda Civic
4 cyl, 1.8 L, Automatic 5-spd, Regular
26 mpg city 36mpg highway
6.10 tons greenhouse gas per year

i tried to find tons per year for generators but I am guessing that since generators do not run all year there is no easy measurement.

I found a stat that says one gallon of gasoline = 20 pounds of co2 emissions.
http://www.fueleconomy.gov/feg/co2.shtml

how much you run the generator tells you how much co2 you will add into the air.

I am pretty sure that a range extender generator wouldnt meet 6.10 tons per year. that would be burning 610 gallons per year in a generator to meet a honda 4cyl's amount of co2 it emits. if you drive the car 10000 miles a year and get 30 miles per gallon you would burn 333 gallons, that 6660 pounds of co2.

I would highly doubt youd be running the generator enough to burn 333 gallons in one year.

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Duncan

· #17 · Feb 14, 2011

Hi Michael

I would highly doubt youd be running the generator enough to burn 333 gallons in one year.

That would depend on - number of miles and the amount of energy you were getting from the grid
A home made hybrid with a small battery getting most of its power from the gen set would probably burn twice that in 10,000 miles

The more you get from the grid (bigger your batteries) the less you will burn - but running a gen set - to produce power to run your motors will be much less efficient than using the IC engine to drive the car directly

nimblemotors

· #18 · Feb 14, 2011

cyclops2 said:
How dirty is a DIY 15 KW generator powered by a Honda 4 or V6 complete with fuel tank & muffler system ?

If you ran an automotive engine intact that powered a generator, it wouldn't nearly as bad, then it would only be the loss of efficiencies
from power translations (85% ?), a trailer (2 more wheels) and the aerodynamics (could be MUCH worse).

But now it isn't a simple $500-1000 generator-on-trailer, it is a major project.

You can cut-off the front-end of a crashed Prius, and there you have it,
a fuel efficient, smog-legal, electronically controlled engine and generator.
A major project to make it work, you must know how to interface with all the computers, etc, and a good-front-end salvage Prius is about $3-5k,
but the end-result would be more ideal.

But then why not just buy a Prius, and make it a plug-in if you need EVness.

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michaeljayclark

· #19 · Feb 14, 2011

sure, in a series hybrid EV then sure, a generator trying to produce enough electricity to run 200 amps constantly to drive the ev at 40 mph and above would mean the generator would be burning at least 1.6 gallons per hour. AC system cars a little less, DC system cars a little more.

drive a car 4 hours per day, say 5 days a week. thats 32 gallons. 52 weeks a year thats 1664 gallons per year, 33280 pounds of CO2. 16.64 tons per year.

even if the genset burned 1 gallon per hour for lower speeds the numbers would still be the same as using a honda 4cyl engine for the DIY generator. no hard numbers but a gas 4cyl engine burns the same as a generator 992 cc engine over time.

BUT... (there is always a butt)

we are not trying to justify an onboard genset for a series hybrid. we are only trying to justify a genset as a range extender to be used a few times a year.

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michaeljayclark

· #20 · Feb 14, 2011

I'd like to add in that a hybrid like a prius doesnt last as long as an EV and would cost more to maintain over time then an EV with a range extender.

I think the oldest prius I have seen on the road is 5 years old?

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