Tesla battery trailer

Tesla battery trailer

Hi guys,
Just saw this:

I have been thinking about battery trailers for a long time as perhaps a better solution than expensive battery swap stations or scattered supercharging locations.
Why? Because we all know that 90+% of most people's daily driving can be done without any of these things, and as batteries get better this infrastructure will be used less and less until becoming obsolete (not a very good business model).
I have thought Tesla could produce their own battery trailer to take the Model S range up to 500 miles.
500 miles seems to be the holy grail for me in terms of range anxiety, as most people cannot drive for more than 500 miles in one sitting and will need to rest/sleep after that much driving, providing an opportunity to recharge overnight.
With a trailer you could plug in the car and the trailer separately, simultaneously charging both overnight and waking up to a combined 500 mile range in the morning.
Tesla could rent the trailers from their dealership locations, and offer a delivery service for those that require it.
Obviously people would only require the trailer when doing long distance trips over their car's particular range so Tesla could offer a variety of trailers with different sized battery packs but I think one trailer offering an additional 250 miles of range would be a good "catch all" trailer to make initially.

I think this service would give a lot of potential Tesla buyers a sense of security knowing that longer range trips would be possible by hiring (or buying?) the battery trailer.
What's more is that by also using a flat floor mounted battery in the trailer Tesla could create a great deal of additional storage space above the battery for luggage, sporting equipment, etc. This would be handy for those moving house or going on an extended vacation.

Only question I have for our tech minded people is how much do you think a battery pack capable of adding 250 miles range would be likely to weigh and how much would this affect the drain on the car's battery pack by pulling such a weight? Obviously at some point you would hit a tipping point of too much weight being pulled outweighing the benefits of adding additional batteries...I just wonder where that tipping point lies?

What do you guys think?

Vawlkus | 21 september 2012

Impractical. The extra range a trailer would give would be negated by the need to drag the extra weight of that trailer along behind you.
Plus most people have a hard time just driving their cars without having accidents. Putting trailers on a lot of cars would just be begging to see accident rates go thru the roof.

teddyg | 21 september 2012

Great. Thanks for the detailed mathematical analysis Vawlkus (rolls eyes).
Obviously there is a point at which weight becomes an issue, but as many companies are designing battery trailers this must depend upon the amount of range extension you are trying to achieve. There is a balance to be found I am sure. I'm just not smart enough to calculate it, but at least I admit it.

In response to the "dangerous trailers" argument - as I said 90+% of most people's daily driving can be done without a trailer, fast charger, or battery swap station. Therefore these trailers would be needed very rarely for the vast majority (how often do you move house for example?) So to say we would have trailers everywhere is not true. Plus a small trailer is not difficult at all to cart behind you.
This is merely a stop gap to sooth impractical range anxiety fears until the car's themselves have a range of 500 miles. Best of all it doesn't require an expensive infrastructure build out that will only become obsolete over time.

teddyg | 21 september 2012

Other benefits of trailers:
1. You don't have compatability issues between different car makers and the particular battery swap station or fast charging station that you roll up to. For example a Tesla cannot swap batteries at a better place swap station (meaning these infrastructures are even more likely to go out of business as their compatiblity is limited to a smaller number of vehicles).

2. We know that rapid charging can damage batteries if done too often. A trailer/car combo as I said could be charged separately at a regular rate of charge (perhaps at 240v) overnight, with your 500 mile combined range ready to go in the morning.

3. Tesla could build the trailers in order to provide a security blanket to it's potential customers who would be comforted to know that an extended range trailer would be available for their rare long distance trips. This would drive higher vehicle sales for Tesla and as people come to realize just how rarely they travel more than 180/240/300 miles in one day they will realize that they will very rarely ever need the trailer but probably admit that it was an important psychological crutch to lean on when debating the original purchase of their first EV.
Tesla, once producing cars with a 500 mile range, could phase out the trailers as they will have served their purpose as a security blanket for impractical range anxiety fears. This way nobody, providing expensive battery swapping or fast charging infrastructures, needs to go out of business, as they need never start!

Brian H | 21 september 2012

you don't mention drag. The additional drag would shoot the Model S' Cd way above the superb .24 it depends on to get its superb mileage. It would also complicate or negate regen unless there was a very sophisticated system built in to the trailer, amounting to either its own regen (= its own motor/generator for its wheels to spin).

Try it. You won't like it.

Brian H | 21 september 2012

Corr: amounting to either its ...

Brian H | 21 september 2012

As for the security blanket argument, it amounts to saying that the range is indeed inadequate, here's how you patch it. TM is taking on the fear more directly.

teddyg | 21 september 2012

I thought about drag...I just thought that a company as smart as Tesla would be able to manufacture a trailer that was closely hitched to the car, with a very low centre of gravity, that was also very aerodynamic and sleek. I wouldn't expect anything less than the coolest trailer ever seen in the history of trailers from Tesla, but maybe that's too much.
Again in terms of the security blanket...there are already a huge amount of people out there who won't buy an EV because they believe that the range is inadequate (I disagree with them wholeheartedly) but these are the facts and it will take a lot to convince millions of sceptical people to take a chance on an EV for the first time. As I said after they buy the car they will quickly realise that they will never need the trailer 90% of the time but it may just be enough to know that they have the trailer as a back up to push them over the edge for the initial purchase.
I bet Tesla would only need 5-10 or so trailers at each dealership to start, see how much they are used and go from there.

Nevertheless it appears that Tesla is going the supercharging route anyway. This will cost them a lot more than the simple trailer system I am proposing here but I am excited for the presentation on Monday...I will save any more comments on a trailer system until I see what sort of system they are proposing.
I hope its good for Tesla's sake!

Docrob | 22 september 2012

IMHO the frunk seems like the logical spot for a leasable drop in range extending battery, if Tesla were going to go with battery swapping at superchargers these would be the logical batteries to swap as by retaining ownership Tesla would avoid the concerns abut varying quality batteries and ownership. If you had a system at superchargers to swap these then you could pull in perform a 30 min supercharge adding 150 miles and swap the frunk battery for an additional ~200 miles thereby more then doubling the effective recharge rate of a supercharger.

Brian H | 23 september 2012

Frunk or towed, adding more battery is just that: a bigger battery. Swapping requires robotics, inventory, and locations. It also assumes a standardized form factor (electric and physical). TM figgered it was easier to supply electrons.

jerry3 | 23 september 2012

Docrob, -- the frunk seems like the logical spot for a leasable drop in range extending battery

As long as you don't mind the imbalance between front and rear axle load and the increased height of the centre of gravity, the extra wear on the front suspension, and the reduced cargo area (on a long trip you're going to want extra cargo area too. Yes, you can install a roof rack but that's likely to eat up the extra electrons you just put in the frunk.

I believe there are a lot of negatives with this kind of arrangement.

Vawlkus | 24 september 2012

Tesla has already done the math Ted, that's where the 85 kwh battery comes from: it's all ready AT the theoretical point your trying to guess at.
Roll your eyes all you want, it doesn't change reality.

TeslaCrush | 30 september 2012

I don't think it is a horrible idea. The low pressure area directly behind the vehicle will help with the drag concerns as the nose has already displaced the air. The single purpose trailer can be engineered to reduce it's impact on range, for instance, tall skinny tires and extremely light weight build materials plus the weight being sprung will have less negative impacts on range than throwing that weight in the frunk. I won't spend the time trying to figure the math but would assume an 85kwh car would be reduced to 200 mile range with the trailer, then another 200 addition just by a single 85kwh trailer. Add a little more effort and engineering and you are at 500. They could be available at Tesla dealers/service centers or even select locations (U-haul), there cost could also be offset by tasteful advertising on them. There are so many unexplored options. Another would be charging lanes in specific travel corridors, so the vehicle is constantly under charge while driving in the designated lanes. Exciting times, they are.

jerry3 | 30 september 2012


I'd rather see it in the trailer than inside the car but there would be significant software and hardware changes because currently no charging can take place while the car is in motion. You also wouldn't want to use the current charge port to plug into the trailer so a second port and cable would be required. All in all, it would be expensive to implement and impossible to retrofit. (And probably of no benefit at all during mountain driving.) It's an interesting idea but I can't see it ever being implemented.

danielccc | 12 oktober 2012

I think if you want to give a free picture for people to use to ridicule EVs, go with the trailer idea.

If I was in Tesla marketing, I would go ballistic if it was seriously considered.

The supercharger stations are a far more elegant solution (though they need to change the giant pointy alien-robot dildo to some friendlier shape).

jerry3 | 13 oktober 2012


I like the supercharger plan much, much better than the trailer idea. However, the trailer idea is better than the inside the car idea.

Now if only the superchargers actually get rolled out in a reasonable time frame. I had hoped that when the supercharge reveal was done there would be at least some superchargers in places other than California.

aaronw2 | 16 oktober 2012

T-Zero did something like this except their trailer had a generator in it. I think that would be a lot more practical than extra batteries since for really long trips where one can't plug in to charge you could refuel like an ordinary car. Their trailer was designed to track the car to be safer.

Wikipedia article

Alegs | 30 oktober 2012

Okay, i am no specialist in battery-things and not even a good driver but: i know lots of people who have money and would buy a tesla if they just could drive from Zurich to Nizza to spend a weekend, but they do not want to make a break to recharge the batteries. And that is the problem with Tesla, nothing else.
How I alrady wrote, i am no technician and have no clue about cars but i know that u can exchange batteries in notebooks and it should be possible to exchange the batteries on a gasstation - should not be hard work to replace a fully loaded with an empty one... lots of people would buy a tesla if they just had these possibilieties. Im no superbrain, but u dont need to be one to understand that ;-P

Cheers Alegs

Volker.Berlin | 30 oktober 2012

For the record: According to Google maps, depending on which route you choose, Zurich-Nice is approx. 600-700 km (350-450 miles). Regardless of route, while Zurich and Nice are roughly at the same level, you have to traverse the alps, which means significant elevation change.

Brian H | 30 oktober 2012

The battery weighs about 450kg. How is that not "hard work" to swap? And how big an inventory is needed for a system like that? A laptop is not a car.

glenclifton | 1 oktober 2013

New Tesla trailer in Texas!


Brian H | 1 oktober 2013

How does it manage the range doubling?

Chuck Lusin | 1 oktober 2013

Which version gets 335 Miles already?

Timo | 1 oktober 2013

85kWh Model S driven about 45mph in good conditions.

kikiorg | 2 oktober 2013

In case you didn't know, we have a good friend who build a Propane-powered turbine generator trailer for his Nissan Leaf. He runs a cable from the trailer to supplement the batteries (or maybe he disconnects the batteries, I forget.) In any case, he has driven to LA, parked the trailer, then drives around as usual.

PS I have known Phil (aka Peef) personally for over 10 years. His modification is very safe and solid. I can tell you many other stories about some things he has done, but suffice it to say he did a grand job with this!

kikiorg | 2 oktober 2013

glenclifton is this for real? There are no links or other source. Would love to read more.

Same for the original posting -- are any of these more than proposals?

Brian H | 2 oktober 2013