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Range Extension

Especially in the first several years it will be difficult to drive long distances in Europe.
Because there won't be enough places to quickCharge or to swap batteries.

Have you ever thought of a range extender that could be placed under the hood?
A small combustion engine that could run on long distance, or even a fuel cell.
(a similar concept to Opel Ampera)

The 300 mile battery on the S can not be charged in 45 minutes unless it is drastically different than the roadster, where the charger port is limited to 240V and 90A as far as I can see, which should take about 3 hours to charge.

Add to that the new charger standard only defines up to 70A, and word is that the installations going on so far are only 30A.

A 7.5kW fuel cell would be perfect for those cross country road trips. If you get 4 miles to a kWh then the 300 mile battery should be 75 kWh, and if you are cruising at 60 mph then you are burning 15 kW, so if half comes from the battery and half from the fuel cell, you could drive for 10 hours straight, or 600 miles. Then even if you do spend the night at a hotel without a charge station, the fuel cell can recharge the battery over night.

"The 300 mile battery on the S can not be charged in 45 minutes ..."

They have been stating officially all along that the Model S will be able to be charged in 45 minutes. What information do you have that the rest of us don't to make you believe that they will not ship it with quick charge support?

It's interesting how some can say..... just drag along a 7.5 or 10kw generator..... without posting the data or link to the size of the fuel cell or generator PLUS gas tank.
Remember it has to be a heavy duty generator not a toy that you buy at Home Depot. Peek power will be important. When I stomp on the gas I don't want to kill my generator.... or wait you mean now we have an entire electronics package to balance the load between battery and generator... looks like it is going to be cheaper to just drag around a spare battery.
I've already posted a 10Kw spec and it's 5' x 2' (size of an extra battery) without mounting structure or fuel tank. not to mention the weight.

Here's what I want for range extension: a level 3 charger in Erie, Pennsylvania.

That would get me as far as I ever want to go by automobile. :-)

(Some hotels in Columbus, Ohio would also need to start having parking spaces with outlets, but that's another matter.)

The fact is that there are going to be plenty of level 2 and level 3 chargers in Western Europe, very soon. Western Europe is tiny. Eastern Europe may lag, but it's not that big either. The US has much more severe problems with lack of fast charging.

The 300 mile battery on the S can not be charged in 45 minutes unless it is drastically different than the roadster, where the charger port is limited to 240V and 90A as far as I can see, which should take about 3 hours to charge. (psusi)

It will be drastically different from the Roadster. That's the only way it can go 300 miles. It also has been stated in another thread (reportedly from a sales person) that the Model S charge port will not be the same as the Roadster's precisely because it must be capable of charging at a higher rate. Adapters will be available (though not necessarily included) and those will of course only allow charging at their respective specifications.

If you get 4 miles to a kWh then the 300 mile battery should be 75 kWh, and if you are cruising at 60 mph then you are burning 15 kW, so if half comes from the battery and half from the fuel cell, you could drive for 10 hours straight, [...] (psusi)

The Model S' 300 mile battery will have about 90 kWh. That figure was repeatedly implied by several interviews with Elon. Pulling a trailer (which you seem to suggest) will completely invalidate your calculation due to increased weight, aero drag and rolling resistance. I would not be surprised if the Wh/mile would almost double (due to the fact that the Model S is extremely streamlined for efficiency, otherwise you would not get 3+ miles/kWh in the first place) which would defeat the purpose of pulling a trailer...

"They have been stating officially all along that the Model S will be able to be charged in 45 minutes. "


"The Model S' 300 mile battery will have about 90 kW"

90 kWh? That would be almost double that of the roadster and only need to be that large if the S only gets 3.3 miles per kWh, when the roadster gets more like 4.5.

To get back on topic here... There are a lot of people that are very negative about range extending trailers. If they don't want to have one that is fine. Don't buy one. The basic question here is whether or not Tesla will support this feature with the Model S.

Living in Texas the closest Tesla store is in Denver. I haven't calculated the time it would take to drive back home to Dallas if I get the 160 mile range Model S that I want, but that is one example of where I would like to have a range extending trailer.

I also agree with others that this is not something I would every day. I plan to use my Model S as a commuter car driving 60 miles a day at freeway speeds.

I was puzzled by all the statements that a range extending trailer would not work so I asked the North Texas EV guys about this and they gave me a link. This seems to be a settled fact that not only is this possible, it is more efficient than an equivalent ICE vehicle. So why all the complaining??

Here is the link:

It does not seem like it would be too hard for Tesla to support a rear plug for this. The extra hardware needed (if any) would be pretty trivial since all the power goes through the one central power module anyway.

I agree this is not the perfect solution (we should all drive electric all the time, of course), but until you are within range of the nearest Tesla store and don't want to burn a week of vacation taking your car in for service, what other options are there? You have to admit it is better than loading your car on a a semi trailer to haul it from Dallas to Denver...


santana338, thanks for the link! (I repeat it here b/c I hope it will come out as a clickable link within my post. It is somehow broken in yours.)

I have never seen a thing like that before and I must admit it looks cute and much more useful than I would ever have imagined a range extending trailer.

Well engineered! I wonder what Tom the EV Tinker t'inks of the Toyota/TM RAV4EV project.

Tesla has said before that they want nothing to do with gasoline engines, up to AND INCLUDING range "extenders".

I agree that a range extender like the trailerable one used by the RAV 4 is a great idea for now, at least until hi amp (45 minute or swap out stations) charging stations are nearly as available as gas stations. I don't like to wait 2-10 hours to charge the car in an area I don't want to stay. Putting a plug and hitch on the back of the car is peanuts for Tesla to install and could be an optional extra for those of us that need and want it. A rentable trailerable generator would work great for just those few trips for those of us that really do travel long distances in the back country. In these situations this could be a life saver. I believe that the model S with this feature would be much easier to sell and I would be very tempted buy. Without it, the risk of getting stranded 40 miles from the nearest village and out of cell phone coverage would be to much to think about.

@Volker EU#P1. Ooops. My HTML was a bit rusty on the link. Thanks!

@Vawlkus. While I applaud Tesla for taking the stance to eventually make ICE vehicles obsolete, until Tesla start using traditional dealer networks or are able to get states like Texas to change their laws, there will not be a Tesla store in my state. The only logical way for us to get our Teslas is by renting or having a range extender and buying a car out-of-state to drive home (unless of course we go back to semi-trailer car haulers to deliver from a store to a customer, but I think that would break my state's law). If we were to just drive and charge, by my calculations it would take over 5 full charges to go the 820 odd miles from Denver to Dallas.

So while Tesla doesn't have to sell a range extender, I would think they could sell a lot more cars to those of us who may have a legitimate need for one if they just support a plug and the ability to have the range extender.

I don't want to pay for, and haul around, the bigger battery for my daily 60 mile commute just so I can drive 285 miles to Houston without stopping once or twice a year

Think of all the range anxiety naysayers that would just go away with this relatively simple addition.

If there was an SAE standard plug for range extending trailers, there wouldn't be any discussion. It would be a "no brainer" to put in. And maybe the existing standard charging plug would work for this situation. I don't know.

Tesla may be ahead of the SAE curve like they were with their first roadster charging plug, but this could really help with the initial uptake of these great EVs within the general population.

I guess an aftermarket extender connection could be jury-rigged, as long as the controller can suck and blow at the same time (volts). ;) The Toyota extender supplied up to 20KW, so I suppose it would be able to handle most driving and charging requirements.

santana338, no HTML required. Links are automatically converted to be clickable in this board.

As for delivery and service, AFAIK Tesla takes care of that by their own. It seems standard for Tesla to have your car delivered to your door (or the door of your choice) on a car transporter, regardless of the size of battery you order. For service they send their "rangers" or in the worst case they will take car of transportation to their nearest facility.

Mind you that I don't say I like or dislike that, I am just stating what I think is Tesla's take on having customers in Texas (or anywhere). So from their point of view, there is no need to support range extending trailers, or at least your particular argument does not hold.

Also, if you think it's hard dealing with a store in the next state, think about the fact that currently Canada has 1 store for the whole country. As it's in the approximate center of the country, those of us on the coasts have a lot further to go than you do. Something to keep in mind.

The Toyota RAV4EV Longranger trailer was aftermarket wired to the regen circuits that were in the front of the car. LONG heavy wires were run from the back to the front.

The RAV also charged slowly, and another aftermarket company (Manzanita Micro) built a faster charger, which also required long cables to the front regen circuits.

May I point out that Toyota did not wire, nor recommend wiring such additions. Yet you expect Tesla to do this for you, when they already have a 300 mile battery that would greatly help on these long trips, especially with fast charging, which you don't want to buy.

You also don't seem to mind paying several thousand for a charge trailer, with loud (Longranger engine raced along at several thousand RPM continually) gas engine, generator and controller, and they had to stop often for refueling. The trailer had special steering for those who needed "no brainer" connections, so they could back up. Of course, you could do it better, and cheaper than a bunch of hack engineers.

Although Toyota RAV4EV drivers had this option, NO ONE used it, on a car with "only" 120 mile range. Some did do the faster charging option, but the trailer was too much money, hassle, on and on. You would think there was a reason.

I plan to buy the 300 mile battery for longer trips. If I had to drive 890 miles once in a while, they have rental Priuses, Ford hybrids, Volts, even. That's what I would recommend to you.

I am not "down" on the trailer. It's just that I've been there. I wish you luck on doing your own experiments and getting your own experience.

I have a suggestion for anyone concerned about range extension. If a 300 mile range is insufficient for one day of driving. And extended range is required for multiple days & trips each year, you should consider getting a Hybrid vehicle to use as your primary vehicle. A pure electric vehicle is not for everyone (due to driving habits, price, etc.). When I read the suggestions about trailerable range extenders, it's like trying to fit a square peg into a round hole. Doesn't Fit! Purchase a Prius, or that new Lexus Hybrid and be happy. Very soon you will be able to get a plug-in Prius, or some other plug-in hybrid (ie. Fisker). Enjoy.

@Volker: Thanks. I was not aware of the delivery-to-your-door aspect of Tesla customer service. I was aware of the Ranger program. So I guess I shouldn't have brought up the "haul the car back to the store" argument.

@Roblab: Thanks for your comments on your experience with RE trailers. It is nice to see some concrete reasons why this is not a "no brainer".

I talked to Jane at the Park Meadows store and she told me Tesla is looking to expand into Texas as part of their Model S roll out. They will be fighting the good legal fight on that one. She also confirmed that Tesla will deliver to the door if the stores are not open when the car is ready.

And I have to admit that I have a 2 car family. We normally take our family vehicle on the longer drives and when we do replace the current ICE familty vehicle, the plan is to buy a hybrid.

The Tesla is intended to be used just for commuting (and on parent's night out of course).

Thanks for the discussion. I can see that I no longer need a range extending trailer.

Let's talk about using the Tesla battery pack as a backup generator for my house now... Oops, there is probably already a thread about that somewhere. :)


It sounds like the charging port is going to be in the back of the car. As stated before, I don't know if this could be used for charging-while-driving but I still think that if that is the case, it would be worthwhile for Tesla to design their charging circuits in a way that would at least allow the option of a range extending trailer. I don't see how this would add much or anything to the cost of the vehicle, assuming is doesn't need a different or additional inverter. It would leave the door open for people who are interested and allow for 3rd parties to develop and market this option.

Since the Model S will not have a trailer hitch (see Franz's blog) it becomes a moot point.


the PEM inverter that turns DC from the batteries to AC for the motor is used as the on board charger when the vehicle rests. When charging, the PEM runs as a rectifier, converting grid AC to DC. As I understand it, the same part cannot perform both functions at the same time.

Charging while driving would require an additional charger or a separate DC input charging port. So there is extra effort.

In order for it to go both ways at once, the car's AC would have to synchronize with the applied power, as any PV system (like the one on my roof) has to do to push back at the utility to turn back the usage meter.

Yes I am aware of that. Problem is, the AC frequency is in sync with the motor RPM (see PEM video). So the power source should sync their AC frequency with the current speed. Usually this requires an inverter just like the PEM that starts from DC and turns it into AC. Sounds costly and ineffective to me.
Would be easier to feed DC to the car system.

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