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Why are there no on board generators?

34K views 138 replies 36 participants last post by  lkcl 
#1 ·
Hello everybody.

I'd like to know why nobody has ever decided to mount a on-board generator to use when battery power drops too low??

even if it uses gas, many would appreciate having the extra range, and it would probably be quite efficient cuz you're not revving the engine up and down with a throttle, nor are you losing efficiency by shifting gears.

plus the chevy volt does either this or something similar.

why don't we all add a on-board generator to our EV's????
 
#2 ·
Several topics on this and i've gathered a few reasons from the previous posts...

This is the DIY ELECTRIC CAR (not DIY HYBRID ELECTRIC CAR)

(a) Many people are not concerned with range of more than what they
are getting now, as they are being used for local/commuter cars.

(b) Many people are converting partly for the environmental reasoning


Note: The cheapest combination i've found is to build your own genset using a small engine and generator head. 10kw for 1500$ and about 250lbs (with all brackets and chassis mounting brackets) I am not sure how fuel efficient the small engine is though...3000$ and 500lbs for 20kw...hmmm....
 
#4 ·
is it something like this that would do the job?

(I hope I'm not making a major error about the type of generator I'm thinking of)
http://cgi.ebay.com/John-Deere-9750...ain_0?hash=item230292db9d&_trksid=p3286.c0.m1

It doesn't weigh TOO much, and seems it would do the job. price good too. I'm guessing such a machine would consume around .8-1 gph. travelling at 55mph that would mean somewhere between 55-66 mpg with gen running.

please correct me if I'm making a nooob error somewhere in my calculations!!!
 
#5 ·
I'll try to answer your questions as best as I can.

this generator is 6.7kw hours of power, which for most people when run a 144 volt system means 46.5amps of power ... which isn't quite the power needed to sustain a normal 2,500lbs vehicle at highway cruise.

You would also have to deal with the idea of more electrics to deal with the charging on the go, the storage of the gas, the space of the generator, etc. ... in the end if you want it to be cheap a gen set is not the way to go. To much hassle for the benefit.
 
#6 ·
why don't we all add a on-board generator to our EV's????
well.... cuz then they would be hybrids, not EVs. The whole idea is to get completely away from that dino-juice ya know.... ;)

but more seriously, for the average vehicle, to get enough wattage to contribute directly to the drive, the generator would be BIG and expensive and heavy and take a lot of room that could otherwise be used for a couple more batteries.

A successful EV experience demands a bit of an adjustment to expectations. Its probably not going to be a race car or a x-country RV.... but it CAN be a very practical in-town commuter.

d
 
#9 ·
A few more reasons are:
Generators don't have all the emissions stuff, and they put a ton more crud in the air, in some states it would not fly

It's not super efficient without the right gear With a plain generator you turn combustion energy into mechanical energy into ac electric energy then into dc electric energy then back into mechanical energy

A charger for this type of setup is very expensive 3000-5000 usd is a deal

I have seen some very successful ones done using a small motorcycle engine driving a purpose built generator that pumps juice directly into the batteries. The moto engine is better on fuel and emissions and the whole setup is more efficient They claimed to get better mpg than the vehicle did with the gas motor.

The motor providing cruising power for more range is definitely an option, but to pull it off well, with good emissions and efficiency, I think you end up spending a good amount of money.

Most of us have a gas car for long trips and en ev for shorter trips, so I think that's another reason a lot of us have not done something like this
 
#10 ·
It boils down to break even points.... and how much you are willing to give up for the convience for those rare trips it might be useful.

That Generator costs will weigh ~100 kg... and will only provide ~6.2 kW at a continuous rate.

This generator is using ~100 kg of weight... with LiFePO4 giving ~100Wh/kg ... in order to put this generator on board you are giving up 10kWh of battery capacity worth of weight.

If that 10 kwh you gave up would have allowed you to just use the EV and no gasoline ... you would have been better off / more ahead if you had just used the 10 Kwh of battery instead.

This generator will not provide for the peak power surges a EV will need during acceleration and such... so an additional battery pack would still be needed for those peak power times.

Generators like this could be used to extend the range of an EV ... how much depends on the efficiency of the EV and the average speed of travel ... even a 6 mile / kwh EV which is a pretty good number to reach ... could only travel at ~35 MPH under the power of this generator... The Volt is looking to use a ~50kW generator to be able to provide enough juice... which still does not handle the peak loads they are expecting of over ~110 kW... so an additional ~16 or so kWh battery is also included to handle the peak power needs / loads.

Range extention gasoline powered generators would be better used ( in my opinion ) as built into an easily detachable trailer... that way the extra 100+ kg of weight can be left at home on those trips that the extra range is not needed... as in ~80% or more of ~80% of the trips ~80% of the population makes.

The attraction to having it built in as GM is doing with the Volt is just for convience ... they are giving up allot ... in order to have that conveince ... for a small % of trips ... but it might work to sell it to the public.

Hopefully once the public starts to buy some of these REEVs & some of the PHEV like the Volt and such ... hopefully people will begin to see a bit of the reality of how rarely they ever use the extended range feature ... hopefully it will open the eyes of the public to see that it isn't needed... and then like pulling other trailers for boats and things ... people will leave the range extention generator at home like they leave boats and such ... when they won't be needed them... and just drive normally as a EV for the majority of thier trips.

----------

As for the efficiency ... a generator can be more efficient ... but it might not be ... it will depend on exactly how it was built... that particular generator is not particularly efficient.

For that Generator to use ~1 Gallon of gasoline in ~1 Hour .. and put out ~6.2 kWh in that ~1 Hour ... that generator is converting the ~36.6kwh of energy that 1 gallon of gasoline only at ~17% efficiency... even if your electric motor is ~90% efficient that means you are only ~15% efficient from gas tank to wheel... Modern efficient gasoline engines are allot more efficient than this... it isn't that hard to get a modern gasoline engine to get closer to ~30% efficient.

Even a modern ~30% efficient ICE attached to only a ~80% efficient generator / alternator ... would still yield ... ~24% efficiency gasoline to electricty ... which is still significnatly better than this example generator.

----------

I seriously doubt that generator would pass emissions tests ... ;)
 
#16 · (Edited)
I remember the story on that guy with the rAV4. He convinced the folks at AC Propulsion to sell it to him because the deemed the trailering was not the biz they wanted to get into for an EV. They (AC Prop) used it on ta yellow model TZero on a cross country run.

The motorcycle genset idea is good. You can get a 400cc Yamaha FZR engine and adapt/mount two 120VAC generators (http://www.blastwholesale.com/proddetail.php?prod=GSH11158) to it you'll get ~20KW average and 24KW surge. Stay at ~20KW though. All you'll need is 26.8HP average so if you can tune the 400cc motor for best efficiency at the required 3600rpm - 4000rpm to ~55-60HP then you'll have an awesome genset that can work as both your range extender or power your house in a blackout.

Once you rectify the AC out from 120VAC you should get (120*1.414) - (1.4V ["diode loss"] + 12.0V ["Ripple voltage lost" after filtering]) = 156.28VDC. This should keep your 156VDC pack close to 80% SOC.

There much more to do but you got the idea right?
________
Live sex
 
#19 ·
An AC genset with a slip-ring (not permanent magnet) alternator could be adapted to charge the batteries, etc. A PI based regulator circuit could regulate the (normally 12V) rotor slip-ring voltage to give a constant current output to charge the battery.

I quite like the idea of a genset trailer for my MR2 conversion. NZ is quite spread out and there's definitely need to travel 400-500km quite often.
 
#23 ·
There is an infrastructure in this country called gas stations and the public is very well aware of it. There is no infrastructure for electric plug in cars and the public is well aware of it. There is not going to (EVER) be electric plug in cars with the thinking of the people on this site. They just don't get it!!!
 
#25 · (Edited)
There is an infrastructure for plug in electric cars, its called the electrical grid and MORE people are aware of it and use it than the gas station infrastructure.

Would the grid need to be upgraded/enhanced as more people get EVs? Yes. Does the full grid upgrade have to happen right now? No. It can happen slowly just like the adoption of EVs...

Can existing gas stations/convenient stores/hell near anywhere be retrofitted to have EV charging stations as well? Yes.

I think the people on this site do get it and thats why we are here talking about what we talk about.

However please enlighten us with what you do get? I, as well as a many other really smart members of this site would like to know...
 
#24 ·
A small gen set could mean driving 20mph home instead of walking.

I don't know about 144v but a plan old alternator can be made to charge 48v with a different regulator.

Convenience stores should really offer cheap/free charging for EVs. We just need to explain to them that there will be customers stuck shopping while ther car charges.
 
#32 ·
Isn't it a case that if you inadvertantly find yourself running out of charge you just have to stop somewhere for a little while and let the batteries recover a bit and then go a bit further?

I would avoid running that close to the limit in an EV in the same way I would avoid running on fumes in and ICE car so I don't see 'suddenly running out' as an issue.

For going the distance I guess I would plan my journey to include charging points in the same way I would with gas stations. The distance may not be as far but I would plan differently.

Don't forget that at the dawn of motoring petroleum spirit was purchased in 2 pint cans from the occasional drug store. Then some bright spark figured there was a business in selling pumped fuel to the motorist.
 
#35 ·
Well i don't think it's a generator "myth", it's more like a safety net like you stated.
Even the greatest planners will have their plans changed.

As sad as it is, most people don't plan.

Also what's quicker, running low on fuel (gas) and stopping by a gas station, fill up in less than 10 minutes and on your way you go or stopping by 220 outlet and wait a few hours to charge?

Until we have the batteries and the quick charge stations, a generator will always appeal to the mass public.

I would love to be 100% electric only but i wouldn't want to be limited by the batteries/charge.
 
#36 ·
I would love to be 100% gas only but i wouldn't want to be limited by the size of the tank, that's why I have a mast and sail and a horse box trailer with a horse and rope and I carry extra fuel in cans in the trunk.
Excuse the deliberate misquote but you might get the gist.

If I was driving across Australia I would carry all the fuel I could carry, a bike, a sail board, etc just in case. But I wouldn't on a drive where I knew it was within tank range and I could fill up at the other end for the return.

An EV should be like that. The driver would consider if the trip was within range. If not then other precautions can be taken if needed.
Mine would be a long charging lead and a map of EV friendly stops and EV club members with charging points. Charging would then take place when I stopped for a comfort break and a coffee and donut.
 
#37 ·
Correct but not everyone will be able to do that and we are talking about mass public.

If i have a car (ev or not), my main reason on driving it, would be for speed and convenience.

Edit: speed as in to get things done faster...

Stopping to charge (for 1hr+) is not going to work out for lots of people and yes, you could say,use a regular car but then we will never get the EV charging stations etc because no one is buying/building the cars that requires them.

If all that requires (for a peace mind) is to have a generator for safety net, than so be it.
 
#40 ·
Okay so we dont have a charging infrastructure yet, but i do remember when the first wave of EVs came out in the 90s,(EV-1 Rav4 EV, Rangers, S10s, etc) They did start to build an infrastructure of charging stations all around major cities, that would have expanded had the EV programs not been killed by the same fools that are now begging for financial aid from the same people who they STOLE the EVs from...

Hey I am all for gensets, I wanted that one lightweight wankel version until i found out it was somehow associated with UQM..which essentially means they will sell it to you in a fair trade for one of your testis...(gotta give props to COS for that one)

I do agree that we will need gensets for now, and when the infrastructure is built to where people wont even have the gensets turn on..since they will be opportunity charging everywhere, store, mall, work, movies, etc....then we can start to make them smaller and less significant...additionally solar tech will be improving and other forms of alternate energy which can also help make the genset less relied upon...

We have to all agree that just as it was pointed out that the use of gasoline was phased in...it will have to be phased out....we shouldnt expect it to be so black and white...we have to give the oil companies a chance to buy the alternative energy companies and close them...;) oh sorry,...have them run around in circles and produce nothing...



Correct but not everyone will be able to do that and we are talking about mass public.

If i have a car (ev or not), my main reason on driving it, would be for speed and convenience.

Edit: speed as in to get things done faster...

Stopping to charge (for 1hr+) is not going to work out for lots of people and yes, you could say,use a regular car but then we will never get the EV charging stations etc because no one is buying/building the cars that requires them.

If all that requires (for a peace mind) is to have a generator for safety net, than so be it.
 
#38 ·
I have taken a lot of time to consider the option of a generator and to be honest I wouldn't bother unless I was out in the middle of nowhere, a desert for example. It would need to be one really big and heavy generator to be able to put in more energy in less time then plugging in will.
I wouldn't want it to be running while I am driving either, especially if it were in the vehicle and even if it were it wouldn't make sufficient difference for me given the extra weight I would have to carry to have it there.

If it were in a trailer then I would have the weight of the trailer as well and if I left it running while I was off enjoying myself then it probably wouldn't still be there when I returned. If I stayed near it then I would have the noise of running.

Maybe over in the UK we have 240v everywhere and that makes a difference to charging capacity compared to the USA and, apart from some parts of Scotland and Wales there is 240v pretty much everywhere.
 
#39 ·
Electricity may be everywhere but its not accessible unless there's fast charging (and billing) infrastructure available. You can't just open an underground pillarbox and connect jumpers to your car..... well, you can - just don't get caught. :)

I wouldn't bother with a genset trailer if there was a sub-20min bulk charge available every 100km.

It'll happen - maybe not in the next 5 years or so though. I work for a power utility and it is an area of interest for developing charging infrastructure in the near future.
 
#41 ·
Electricity may be everywhere but its not accessible unless there's fast charging (and billing) infrastructure available. You can't just open an underground pillarbox and connect jumpers to your car..... well, you can - just don't get caught. :)
It's been known for folks to 'borrow' electricity from dubious sources.;)

I figured it wouldn't be a problem in the UK as news reports of EVs and the occasional car or gadget programmes seem to show people stopping outside a pub/bar and going in with a plug and asking for a charge up and buying a pint while they wait.
It should be fairly easy to work out the cost per hour of charge from a standard domestic outlet and then just offer that amount and a little bit for the trouble.
 
#42 ·
Couldn't it be as simple as a 220v outlet with a quarter/dollar timer?
Right next to the pay air.

Charge twice what the electricity costs plus they will probably buy a Coke and a snack since they are stuck there for 30+minutes.

They could even make a feel good ad campaign.
______ is committed to being part of the solution so we will begin offering EV charging across the nation.
Then there gas customers could feel better about buying from and oil company that cares.
 
#43 ·
Couldn't it be as simple as a 220v outlet with a quarter/dollar timer?
Right next to the pay air.

Charge twice what the electricity costs plus they will probably buy a Coke and a snack since they are stuck there for 30+minutes.

They could even make a feel good ad campaign.
______ is committed to being part of the solution so we will begin offering EV charging across the nation.
Then there gas customers could feel better about buying from and oil company that cares.
So not only do we have some seriously smart engineers on this forum, we also have some crafty marketing execs!

I do honestly believe it could be as simple as a creditcard swipe machine and an outlet...
 
#44 · (Edited)
Well I work in the electric utility industry and we have already concieved electric filling stations, it is a long ways off as the battery technology does not exist yet, but it goes something like this.

You pull up your vehicle. exit it and go inside to a safe area. Then an attendant pulls the car up on a steel platform (ground plane), The attendant connects the vehicle to the charging apparatus, which will have to be standardized to say 480 or 600 volt 3-phase. When charge is complete, the customer pays, the attendant disconnects, and pulls the car to the waiting area. Off you go 10 to 15 minutes later.

Basically to make it work the electric station will be a 69 KV or higher substation, depending on how many charge stations that can be operational at any one time. I mean 20 to 60 Kwh in 10 to 20 minutes is one hell of a lot load multiply that by 4 charge stations at one time and WOW.
 
#46 ·
You pull up your vehicle. exit it and go inside to a safe area. Then an attendant pulls the car up on a steel platform (ground plane), The attendant connects the vehicle to the charging apparatus, which will have to be standardized to say 480 or 600 volt 3-phase. When charge is complete, the customer pays, the attendant disconnects, and pulls the car to the waiting area. Off you go 10 to 15 minutes later.

Basically to make it work the electric station will be a 69 KV or higher substation, depending on how many charge stations that can be operational at any one time. I mean 20 to 60 Kwh in 10 to 20 minutes is one hell of a lot load multiply that by 4 charge stations at one time and WOW.
Not exactly the K.I.S.S. method. Sounds cheap too.;)

Sorry Bowser330. I am taking business classes at night.
 
#49 ·
Correct but people are more concerned about how quickly can i continue driving.
Planning is great but things don't always go according to plan.

EVs need to be ready for those daily back and forth errands. It would totally suck to have your day wasted because you needed to wait a few hours to charge because you used up your 40 mile range and noticed that you forgot something at the store (or some where else).

How about in emergencies? You just plugged in your EV but an emergency came up but now you need to take a cab because your EV is still charging. Yes you could instead use the oil base car but how many people have more than 1 car?

Good battery packs are here but still a bit too much for the regular person.
 
#50 ·
How about in emergencies? You just plugged in your EV but an emergency came up but now you need to take a cab because your EV is still charging. Yes you could instead use the oil base car but how many people have more than 1 car?
A generator wouldn't really help in this case unless it was big enough to run the car directly. If the batteries are flat then it isn't going anywhere for a while until it has a bit of charge in it whether bu being plugged in or via the generator.
Of course, if the emergency isn't very far then the car doesn't need a full charge to get moving so it wouldn't take that long.
You could take a charger to keep topping up the batteries as you drive to the emergency but then you may not need to if you didn't have the weight of the generator.

I don't know, we could come up with an infinite number of senarios to debate the value of a generator or not.

I'll agree to disagree with you and see if I can plan my life effectively around my EV, when it is running, as I think I may. If not I'll come back and tell you I have a generator!:D
 
#53 ·
I have heard of a university project that added a platform onto a hitch, added a very large generator onto the platform, then plugged the charger into this while running... I vaguely recall that the overall "mileage" was very similar to the stock motor...

The nice thing about the platform is you do not need to haul it around all the time...
 
#61 ·
I have participated in the thread "building your own series hybrid generator" and the biggest obstacle was finding a generator head that could produce the required amps and volts without weighing as much as an aircraft carrier. My question is simply: if the OEM guys can create such a generator, why not anyone else? What generator head is the volt using? Is it made from unobtanium or something that a DIYer can't/doesn't have access to? TJ and I were looking at generator heads from aviation APU's, but he hasn't been able to test any of the units he has to see if they can produce the required juice. Anyone have any experience with these, or other sources of generator heads that don't weigh 10 tons? Pelase post if you do.
 
#62 ·
Hi
Lets try this a different way. The public has seen 100 years of perfecting the gas vehicle it can now go up to 600 miles on one tank of fuel. The EV can go 35 to may be 70 miles and has the batteries in the back seat and trunk. Gm looked at all the records it has on customers and found that most people drive less then 40 miles a day. So they make a plug in that will go 40 miles and they have but joe public says what a minute I need to go 600 miles and you know you can't do that. So put in a generator to extend the miles that you will not use. Way because most people drive less then 40 miles. In sales you need to have a product that customers need so give them a generator and in a few years come out with a new modal for less money with out a generator and it will sell. As for the weight Kohler makes one that weight 193LB three cylinder diesel 240 volt 41.7 amps electric start GPH 1.1------- Kubota makes a one cylinder diesel for sail boats that is light and use about one cup of fuel an hour a friend I know has one. I called them but could not get any info from them. The charger would just plug into the generator this will help if you find yourself in a spot were you can't find a plug.
 
#64 ·
Hi
Lets try this a different way. The public has seen 100 years of perfecting the gas vehicle it can now go up to 600 miles on one tank of fuel. The EV can go 35 to may be 70 miles and has the batteries in the back seat and trunk.
minor correction.
A modern EV goes double that range ... 70 to 150 Miles per charge without loosing the seats or trunk.... the 35 to 70 mile range is about ~10 years or so out of date with what modern EVs can do.

Gm looked at all the records it has on customers and found that most people drive less then 40 miles a day.
Minor correction.
the U.S. Federal Government in the census department conducted studies and such... they then publicly released the data for everyone including GM to see.

So they make a plug in that will go 40 miles and they have but joe public says what a minute I need to go 600 miles and you know you can't do that. So put in a generator to extend the miles that you will not use. Way because most people drive less then 40 miles. In sales you need to have a product that customers need so give them a generator and in a few years come out with a new modal for less money with out a generator and it will sell.
100% agree... once people start driving the PHEVs and REEVs they will see first hand that they don't need the generator... and will be much happier to buy the BEV without it built in.

As for the weight Kohler makes one that weight 193LB three cylinder diesel 240 volt 41.7 amps electric start GPH 1.1-------
240V * 41.7A = ~10kW
~193 Lbs = ~8.7kWh of 100Wh/kg LiFePO4 you do not have.
Which means such a generator does not have a performance benefit over the batteries until you have driven more than ~52 minutes straight.

1.1 Gallons per Hour at 36.6 kwh per gallon = ~40.2 kwh in to get ~10 kwh out = ~25% efficiency... not particularly good... but I have seen worse.

this will help if you find yourself in a spot were you can't find a plug.
100% agree... just what % of trips will be longer than ~52 minutes in order to not be able to plug it in?... if that % is high enough for someone it might make a good option ... but for the general public is it as very small % of trips... and for me personally it is a very small % of trips.
 
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