Are you able to drive an EV while its being charged?
 

I was having a good conversation with friends.
(naturally about eco-driving :thumbup:)
And it brought up some good questions.


Is it possible to drive an electric vehicle while it is being charged by a generator?

(Not that you need too. More like a "what if" question.)


I know the newer cars (Tesla/Leaf/Volt) would be a little difficult
but what of the older smaller (home-made?) models?

http://i.treehugger.com/files/th_ima...ctric_cars.jpg
http://www.manufacturer.com/cimages/..._1k_2k_3k_.jpg

Sure just put alternators on the wheels and charge as you drive. Kidding. I can't help myself sometimes.

AC propulsion had a generator trailer at one time called "Long Ranger" so it is possible. You could also have a pusher trailer. Neither are really good options.

If somehow you had an extra battery pack that you used to charge the original battery pack, sure.

ok... ill make it simpler



can i start a generator in the backseat of an EV.
connect the two via an extension cord.
then drive around.

I think you can. At least it better work, because I'm working on something like that right now. A 6kW generator charges a battery pack, and at the same time, the battery pack is being used by the controller. I don't have the generator yet, so it's only been tested as the charger and the controller separately.

the only reason i ask is because these topics were brought up



1. What if i run out of power in an EV?
(can i plug in and continue driving?)

2. What if i want to drive father than the range will allow?
(again, can i plug in and continue driving?)

Besides the obvious downsides like the noise and the fact that you would be deaf afterwards, yeah... Why wouldn't you?

Most commercial built cars have a feature that prevents them from driving off while plugged in to an outlet, but disabling that should be easier than dealing with the generator...

Hi Paul,

I think that would be so cool if you could get that to work !!! A DIY extended range EV would be radical !!!

Does your dsPIC controller have the intelligences to start and stop the generator during the battery charging ? Is the dsPIC controller you are using DC or AC ?

I hope that you continue to tell us about your success with that project. :thumbup:

-Mark

this is what i was referring to

sometimes that failsafe is difficult to bypass

I figured by now, someone would have posted a YouTube clip of just what you're talking about, aloha. But I searched high and low and came up mostly empty.

• I do recall seeing a clip on Britain's "Fifth Gear" tv show where the presenter, after driving the snot out of an OEM electric Smart car, raised the issue of getting stranded, and then loaded a generator into the hatchback, plugged it into the car, fired it up and drove off. But you can never tell if it's for real on TV.

• A member of the Ottawa EV club tried this with his electric pickup (more practical, since the noisy, stinky, hot generator is on the back of the truck, not in the passenger compartment. He tried driving with it running, but I seem to recall it kept tripping the breaker. Maybe a case of not adequately sized generator for the job.

• Your post caused me to hit the local classifieds looking for a 2kW generator. :D I'd need at least that to try this on the ForkenSwift, since its charger consumes ~1200 Watts at its max charge rate.

Found 1 video for you. Not exactly what you're asking, but close. The generator is apparently running the e-motor directly in this clip. The batt pack isn't installed yet. Pretty ghetto. :)

http://www.youtube.com/watch?v=0QIaUl7XcrU

Keep in mind though: most EV chargers only output a fraction as much power as the car consumes while driving. A simple way to look at it: I could easily drain the ForkenSwift's (half worn out) pack by driving it non-stop at about 30 mph for 45 minutes. But then it would take ~8 hours on the charger to bring it back to 100%.

So even if I had a generator powering the battery charger while driving, it would only extend my range a little bit. It wouldn't permit me to drive until its gas tank ran dry. It would extend stop & go driving proportionately more than non-stop driving though.

I was hoping you would chime in :D

so the ForkenSwift uses 1200 watts.
is this a common consumation number?


is a Honda EU2000iA
2000 watts. Noise: 43/49 dB. Weight: 46 lbs.
9.6 hours on 1 gallon.
but it does cost over $1k :eek:
(im sure we could find a used one cheaper)
http://t3.gstatic.com/images?q=tbn:6...0Generator.jpg


at least i have more info to stoke the fire with


1. What if i run out of power in an EV?
(can i plug in and continue driving?)

A: Yes. But only for intermittant driving as the batteries charge slowly.


2. What if i want to drive father than the range will allow?
(again, can i plug in and continue driving?)

A: Yes. But only for intermittant driving as the batteries charge slowly.



The best thing you can do is if you run out of juice is to find a rest stop.
Plug your generator into your vehicle and take a break.
After a while, get back in and continue on your way.

The time spent waiting is only determined by how fast your batteries charge.





Which of course opens the floor to another question.
Quick-charge charger/batteries?


12 min charging time (naturally made for the EV1)
Quick Chargers for Electric Vehicles
http://www.altfuels.org/events/other...s/qkchargr.jpg

This conversation is like music to my ears! :-)

Ill be doing something similar with Belaero, except in DC.

The main pack will be about 5KWH and drive engine will be the new "poppa Etek" and the gen will be an efficient little 7hp ICE (possibly graduating to a 10hp diesel) the ICE will turn a smaller ETEK to output about 6hp (from the gas engine) and 9hp (form the diesel) either one should power the car at speed.

The 10hp would likely also turn an alternator for the 12v and possibly even an AC compressor.

Approximate price for the Gen:

7hp ICE electric start $300
little Etek $500
Fab and mounts $100
Total $900

Diesel $700
Little Etek $500
Fab and mounts $100
Total $1300

Anyone want me to build them one too :-)

Aloha, I read your post again just now and I think there is a flaw in the logic.

* Quote *
1. What if i run out of power in an EV?
(can i plug in and continue driving?)

A: Yes. But only for intermittant driving as the batteries charge slowly.


2. What if i want to drive father than the range will allow?
(again, can i plug in and continue driving?)

A: Yes. But only for intermittant driving as the batteries charge slowly.
* End Quote *

If the vehicle is driving and using the amps as they come form the Gen your not so much charging the batts for future use, your using them as a "pass through entity" so (assuming the gen is matched to the amp draw of the vehicle at whatever speed your driving) youll get to where your going but still have low batteries.

Now, assuming some sort of "dc charge controller" is in place, you could just leave the gen on while your doing whatever it is your doing at your destination if you like.

Do I have this right?
Tom

Hi Sawicki! Yes, the charger, controller, and bms all speak to each other over CAN. The BMS keeps telling everyone what the voltage of every battery is. The controller keeps a running total of the amp*hrs used since last charged. When the pack drops to 50% or so, the charger is informed about this. A relay providing 12v power to the electric start kicks in by the controller. Then, the precharge sequence starts up for the charger, which has 3 relays. One to precharge the input cap, one to put the battery pack in the charger circuit, and one to close the contactor to put the 220v AC power into the circuit with the charger. Then the charger ramps up to the constant 6kW load. If the batteries somehow get fully charged while still driving, the plan is to just stop charging, and not worry about balancing the pack until you are no longer driving around. All this info is just a bunch of numbers sent in packets over CAN, so it's not as hard as it sounds.

The batteries are Thundersky, so they can handle charge rates of around 270 amps, since they are 90 amp*hr, and are 3C rated for charge and discharge. The actual charge rate I hope to be around 50 amps. We'll see how the poor power factor of the charger affects the generator. I think it will be OK. I was able to charge at 72v and 20 amps without the circuit breaker blowing, and it was a 15 amp breaker. Heck even at 30 amps it took a while for it to trip.

You coudl have the option of putting the car into eco mode so that it doesn't allow more than 50 battery amps so you could drive until the gasoline ran out, or you could set it to x battery amps, and then the 50% would then still drop (but more slowly) but you could extend your range until it reached 20% or whatever depth of discharge you like.

Unfortunately, no. Chargers vary in power consumption/output.

But you could generalize: it's likely that the max power used by a 110v charger is 20A * 110v = 2200 Watts. (Assuming 20A is the max common breaker size on 110v circuits).

That's about it. Should say however, that at least with lead-acid batteries, you can get an 80% charge much faster than you get 100% charge. Meaning: much more time is spent going from 80-100% than getting to 80%.

I'm waiting for Paul to chime in again. He's talking about a 6kW genset. So obviously he has other plans than my example. His & todayican's examples are examples where the genset can theoretically provide all the juice the electric motor needs to propel the car. So they could drive indefinitely (or until the gas runs out) :P

But I think my example is close to what I think you were asking: "could I theoretically go to the hardware store right now, buy a portable generator and connect it to my existing battery charger, effectively making the car a plug-in hybrid in 5 minutes?" Answer: yes, with the limitations that you get.

One thing I was thinking was, during "drive mode" for the gen (If its a dc gen anyway) one could bypass the batts and controller alltogether, gaining whatever efficiency might be lost on the controller itself and just drive the traction motor with the gen and modulate the gens throttle to adjust speed.

Dont know what the greater of the evils are in this scenario, running through the batts and charging them with whatever isnt being used by the drive motor at any given time, and accepting the electrical efficiency losses of the controller etc, or modulating the throttle of the gen and potentially not having it in its peak efficiency curve (a BIG advantage with serials I beleive)

Something else to make it even more interesting...

Ill be using 60ah thundersky batteries and asking as much as 7.5c from them during full power acceleration (possibly too much, need to do more research)

What if, I limited it to 380a max from the battery pack alone and if I really need a lot of amps, (going up a big hill, etc) add the gen in for the full 450 so the batts would not have to put out more then 6.3c on their own?

So much new ground here... :-)

The only thing is that if you constantly charge to 80%
it lessens your batteries ability to charge to 100%
(shortening the range)

Controllers are probably 99% efficient. If you think of the batteries as a huge water storage tank, and you open up the pipe for the water to start pouring in as fast as possible, if you are at a stop light, the water is filling up. If you want to do some hard accelerations, the tank drains some. If you are happy to keep the batteries at 50% or whatever, I think you could eliminate the controller. It could simplify the system a little bit, but you would be forced into unforgiving eco mode, rather than having it as an optional "average eco" sort of thing.

The parts for the 0-192v 0-50amp charger are around $400, excluding the 50amp 2mH inductor. I have no idea what one of those costs.

I think the controller will always be needed in a road going car (barring some sort of contactor arrangement) to take off and reverse etc.

You probably don't want to do that. You'll either need to massively oversize the generator (reducing efficiency), or continually switch from gen to controlller whenever you need to accelerate a little bit.

I remember this conversation from the EVDL, and I seem to remember them saying that whatever extra the generator provides reduced the load on the batteries. So if you are pulling 7.5C at the controller, but pouring in 2C from the generator, the batteries see it as a 5.5C load. So yes, this would work.

You want to figure out what your cruising consumption is, and then try to size your generator to put out that much, plus a few percent to cover acceleration, hills, etc. That way, your generator is sized to its maximum efficiency. At best, it will have to cycle off occasionally (if you have a tailwind), and at worst, you may have to stop occasionally on a long drive (if you have a headwind) and let it charge for an hour.

That is not true for all battery types, Lithium batteries like to be between 20% and 80% full 40% for storage, the last 20% is where damage is done, lead acid do however tend to like to be fully charged.
For most batteries fast charging will shorten their life a bit but the limit on fast charging is monitoring them to keep from over charging, and finding a way to dump enough electrons in.

A bit of tongue in cheek reply
 

While charging the batteries, som efficiency is lost in the genset itself, and it's unlikely even that Honda generator will last its quoted timeframe on a gallon of fuel. (Look at the specs a bit closer, the quoted timeframe is for 50% total capacity useage.)

You'll also lose a bit through heat as the batteries are charged.

So why not attach the ICE motor directly to the wheels?

Yes, there's a bit of sarcasm involved, but there is an important thing to consider. Generating your own electricity is not subsidized by the government and isn't nearly as efficient as a professional power plant. I suspect if the miles per gallon used by the generator were figured, and it was the only source of recharging for the batteries, you would have an efficient vehicle to be sure, but not nearly as much so as when the batteries were charged by the house current.

I think a diesel genset would be the best choice for a range extender, but it would be nearly worthless in constant driving. It would be highly awesome for city driving though, assuming the weight of a genset would be better than the same weight of additional battery capacity.

Even in electric vehicles the laws of physics still apply. There is no free lunch. If you had a portable genset capable of recharging the batteries after they've been discharged plus driving the electric motor, it would be so heavy and consume so much fuel you'd be better off attaching the engine to a transmission and losing the electric drive altogether.

I agree with the point that it's more efficient to charge from the wall, but the genset is an acceptable trade-off if it's used seldomly (and, if possible, it's easily removed and left at home when not needed.)

The ICE is certainly an option (especially if the car is 4WD/AWD and thus can be electrified easily), but then you're in and out of your powerband. An 80cc or 150cc 4-stroke driving an Etek (especially if you can go with, say, a 72V drive system so you don't have to boost/buck your Etek to match) would be a lot more efficient, if not as clean. A biofueled diesel of equivalent power would probably be even more efficient, with noise and vibration being the inherent problems.

A well designed modern diesel can be quieter and smoother than a similar gasser. Noise and vibration are inherant to older manual pumped diesels, but not a good quality commonrail injected diesel.

Then again a gasser running at nearly no throttle would be very efficient I suspect.

I was referring to a diesel with the equivalent power to a 150cc 4-stroke. Those Kubota rattleboxes come to mind.

Lol, not exactly a well designed comonrail I suspect :D

IMHO the best way to get the get the best of both worlds (petrol and electric) is to have two cars, one petrol and one electric. Drive the EV on majority of trips that you take every day that follow the same route, work, school, store, church, wherever, and take the petrol car when your not sure where you are going. It seems like that when you try to combine the two by adding a gen to an EV you are more likely to get worst of both rather than the best of both.

the original topic wasnt about adding a gen to an EV permanantly


more like a just-in-case

Alohaspirit,

Sorry about being off topic ......

Clev,

You basically described an SAE Formula Hybrid - Formula Hybrid

Most of the SAE Formula Hybrids built use a 250cc 4-stroke driving an Etek for charging. Both Series and Parallel Hybrid systems are used. Some of the teams are using SuperCaps in series with the battery packs to balance the discharge load under acceleration, and to capture regenerative braking energy.

-Mark

CR diesels are less noisy than PD diesels, but still nowhere near as smooth as a petrol engine.

Diesels get additional soundproofing (and extra weight).

A dedicated ICE-generator that would only need to supply the average power drawn during a ride, would be a fraction of the displacement,size and weight of an ICE that must cope with peak performance because it's driving the wheels directly.

David Cloud's long distance EV used 170 watt hours per mile. I've heard of that figure being easily twice that (I'm hoping a couple EVers chime in pretty soon!) So if he went 30 miles per hour, that would be 5100 watt hours total usage.

This Honda generator can produce 4,810 watt hours on 1 gallon of gas. I calculated it according to 50% capacity producing 1500 watts *9.3 hours/2.9 gallons used. For David Cloud's highly efficient EV to burn through 4,810 watt hours (one gallon of gas) he would be able to travel up to 28.3 mph, and burn 1 gallon of fuel in the process.

This larger generator produces 5220 watt hours per gallon at full throttle. This would surely boost his speed, and it does, to 31 mph.

I've owned an old Nissan that could trump 31 mpg if I drove it hard and fast with the AC blasting!

The point of an EV is to take advantage of VERY cheap electricity available at the tap anyplace there is an electric grid.

There must be some flaw to my math because this doesn't make any sense! :eek:

and i steer everyone back on track again :cool:
http://t1.gstatic.com/images?q=tbn:8.../steerhelm.jpg


this isnt a "hey im going on a 500 mile road trip so lets attach a gen" scenario


more like
"this hill expectedly drained my battery and im 15 miles from the house,
can someone drop off my generator so i can drive home"

I think the Volt is going to get around 35 mpg in non-ev mode. Thank you for finding that link! I get a little over 30 mpg in my figgerin'. 1500w*9.3hr/2.7gal = 5166.67 w*hr/gal. Then 170 w*hr/mi means 30.4 miles/gal. It really depends on speed though. Watt*hrs/mile is a measurement of force. So the slower you go, the less force the wind pushes on you, and the further your generator will get you. I think regular cars have an optimal mpg speed of around 50 mph, assuming flat road etc. But as range anxiety insurance, 20 mpg or whatever it would turn out to be in real life isn't so horrible?! If it was once in a blue moon, and you were in EV mode 95% of the time?

sorry for going off topic, mate. I suppose you may have possibly accidentally set off a lively discussion?

Assuming you're in such a scenario, and you drive an EV within the confines of civilization, I'd suggest a pocket with cash for the homeowners you want to plug your extension cord into (assuming the charger is onboard.....)

nah its all good
chat away. evolution is good
(sometimes :D)



just sayin that
i dont, like a lot of people, believe that an EV should be driven attached to a gen.
(kinda defeats the purpose)
but if you must you must

Well, I would have thought it to be a good idea to tote a generator around, but after crunching the numbers, it sounds like a bad one!

I, as one of the "full time hybrid interlopers" was having a merry old time talking about full time gens and "engine more on then off"

Does this call for a separate thread?

Tom

This thread is opening up so many rabbit trails we may have to start a new forum on EM to allow it to evolve fully :D

I have to say, im excited! for a purpose built vehicle like mine, I can get the acceleration using what electric motors are great at (takeoff torque) and range using what ICE's are good at, particularly diesels (droning on for hours on end right smack dab in the middle of their efficiency curve)

and wind up with something nice, possibly even in the 200mpg range.

Using the EcoModder tool, feeding in all the "knowns" and making educated guesses at the rest, it puts the 70mph requirement for my vehicle at about 3500 watts.

Take a 10hp diesel with a 200 gram per kw per hour (got the info here: NEW 10HP Diesel Engine Electric Start Tractor 10 HP - eBay (item 180588653876 end time Dec-16-10 16:21:41 PST) )

using 5.5hp (fudge factor) thats 200 grams x 5 = 1000 grams. there are 3213 grams in a gallon of diesel so 3.2 hours of running time to the gallon.

3.2 x 70 = 224 miles to the gallon

but...

going serial hybrid and using the electic motor as the drive engine, (and using high efficiency and not too expensive etek style motors) your losing say 10% at the gen and 12% at the pack, controller, and drive motor

so 10hp - 10% = 9hp 9hp- 12%= 7.92 so your losing 20.8% to the serial system.

Brings you down to *Only* 177mpg at 70mph

I could live with that, not to mention the 40 or 50 miles of electric only driving youd get from a wall charge)

The thing that I dig is using the next best thing, a transmission equipped motorcycle engine to drive the trike (without an e-motor as the primary motor, you'd need that tranny) your burning 354 grams per kw per hour. damn near twice the fuel...

Makes the 20.8% losses to the serial drive train not look so bad :-)