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model x battery trailer idea

I don't think this will ever come to be but yesterday I was thinking about what it would be like if Tesla made a trailer that basically had a battery as the floor, much like the cars. It could connect to the charge port of the X and double the range. Now, getting someone to fork over tens of thousands of dollars for it might be a tough sell but if you can get around 500 miles out of your car and have some more room for supplies it would make it the ultimate road trip suv. Needless to say, it would be a lot easier to build than an X.
 
I don't think this will ever come to be but yesterday I was thinking about what it would be like if Tesla made a trailer that basically had a battery as the floor, much like the cars. It could connect to the charge port of the X and double the range. Now, getting someone to fork over tens of thousands of dollars for it might be a tough sell but if you can get around 500 miles out of your car and have some more room for supplies it would make it the ultimate road trip suv. Needless to say, it would be a lot easier to build than an X.

Why do I want to pay tens of thousands of dollars to drive past perfectly good Superchargers?
 
I guess it would be feasible if money was no object. I don't think a 500 range would be doable if using a standard 85/90kWh sized battery. The range would be diminished inherently by towing a trailer so you're probably left with closer to 400miles of range. Considering you'll need to stop to charge the X battery from the trailer - the trailer will also need a DC-DC converter and DC charger on board. If you expect to charge at supercharger levels (to minimize your waiting time) then you'll need a lot of room for the charging hardware to charge the X. Plus the AC charger/s to actually recharge the trailer battery too when it's flat. Then there's also the issue of heating and cooling of the battery if you want to get the capacity out of it especially in cold weather. The HVAC unit heatpump is not in the battery normally so it will need to be added to the trailer somewhere and coupled to the battery via some coolant lines.

Certainly doable but certainly not cheap. $50k? Would there be a market for this?
 
I don't think this will ever come to be but yesterday I was thinking about what it would be like if Tesla made a trailer that basically had a battery as the floor, much like the cars. It could connect to the charge port of the X and double the range. Now, getting someone to fork over tens of thousands of dollars for it might be a tough sell but if you can get around 500 miles out of your car and have some more room for supplies it would make it the ultimate road trip suv. Needless to say, it would be a lot easier to build than an X.
I think the idea might work for a limited battery just to supply energy lost to using a tow. But it would require charging capability and limited market for those doing long distance travel with tow
 
. Finally, tesla should rent the trailer.

That's actually an interesting idea. Yeah not many, if any would fork out $30-50k for a cargo trailer they'd use a few times a year on a long trip but if you wanted to do a big family trip you could contact your local service center and rent a trailer to get around double the range and then supercharge effectively twice as fast since you'd be charging two batteries at the same time. Might not make sense to sell, but I could see a market for renting.
 

Cyberax

Member
Supporting Member
Jul 28, 2015
453
366
Seattle, WA
I'm actually scoping such a project.

We've checked that it's possible to inject electricity into the Tesla's HVDC bus with a suitable charging controller. An old S40 with resale value of a brick was used as a testbed and we drove just about 100 meters with external power injection, using a very long extension cord. From the Tesla's side it looks like suddenly the consumption of the motors and AC drops to negative values.

So it should be possible to create a trailer that works in a charge-sustain mode. A portable 16kWh air-cooled generator can be bought for $15000 new and the charging controller needed to upconvert voltage to Tesla's HVDC level costs about $3000. So a $25k bespoke trailer is definitely feasible. Mass-production can bring this price down to $10k easily.

This 16kWh trailer will be able to sustain the speed of about 40mph, so the total range on a fully charged battery can easily be 400-500 miles. And best of all, you can stop any time and the generator will just keep charging the car's battery.
 

Cyberax

Member
Supporting Member
Jul 28, 2015
453
366
Seattle, WA
That is very interesting. Now I wonder if perhaps power walls could be torn down for the modules to make a nice trailer. It could be a flat bed trailer with a box welded on the bottom, to carry toys hundreds of miles.
Batteries have the problem of poor energy density. You'd be well into the rocket equation territory (i.e. you need batteries to carry batteries to carry batteries...). Oh, and the total price will be unrealistically high.

A small 16kW generator-trailer seems much more realistic.
 
Mixing a simple battery hauling trailer and hooking into the Tesla high voltage is easy. Making this affordable and SAFE is not as easy.

Of course, the concept has been done many times already. Tesla isn't going to do it, so that leaves private enterprise.

Since VERY VERY few people have a need for such a product, and the times those few would both need it and want to pay the exorbitant cost are few, the tiny market with an obscure and expensive product is a business LOSER. That means that no logical for-profit business will do it. Cheap gasoline makes it even more or a loser business plan (people will just rent a Suburban for those few times they need a huge car and longer range).

But, I think it's cool, so perhaps it could be a hobbyist thing. The cost is nutty, so a rich hobbyist!

- - - Updated - - -

Just tow a BMW i3 Rex. That's a 25 kW genset in a nice light towable package, plus 22 kWh of battery.

Yes, tow the BMW i3 !!! Or remove the 650cc gasoline generator and put it on a trailer or bumper mount. Cheap and simple.
 

S'toon

Knows where his towel is
Apr 23, 2015
3,702
3,748
AB
Sounds like someone's been paying attention to this thread:
What followed was an idea that Elon tossed out, something he hasn’t mentioned before, although others have. “What if you had a trailer with a booster battery that you could use for long distance driving?” he asked. Then he told the audience that he was running on about 1 hour of sleep in the past 48 hours and might not be thinking clearly. But the notion of a tag-along trailer with an auxiliary battery makes a lot of sense for those times when people are driving long distances and really do need more range.
http://www.teslarati.com/wont-see-500-mile-tesla-battery-anytime-soon/
 
There is a guy on youtube that build a battery trailer and hooked it up to his converted VW Samba. Seemed to work out for him since the trailer was so low profile it didn't add a lot of wind resistance. Complete Tesla Battery Range Extender Trailer Project - YouTube

Difference being though is his EV has a much smaller onboard pack then an S/X. Would have to be a very big trailer to have any difference in range for an X. If you are going a generator route though... makes more sense to just downsize it so it fits on the 500 lbs of your receiver hitch.
 
+1 to the rocket equation comment above. Towing capacities are already limited and we don't need over-heavy trailers, but would be better served with lighter trailers that can actually allow us to carry a load. Since most trailers over 1500lbs loaded really should be equipped with brakes, I'd like to see a trailer with regenerative braking ability and power feedback to the main vehicle.
 
I have a little over a year of towing experience now with a Model X (100D) and an Airstream (FC20). The numbers do not work out to lend themselves to anything like the imagined "tow a trailer with a battery that will give you 500miles of range".
-Range is about cut in half (more if traversing hills or in bad weather)
-a second 100kWh battery (which would be largest and most expensive if we stay in the Tesla realm for the moment) essentially would almost get you back to car-alone range, BUT you would have a 5000lb little home with you wherever that range took you.

I think the idea is cool, but the rocket equation makes it not practical-and then generator ideas come into play, etc.

break break, what about a smaller ambition (for people who want a RV trailer)?

1) Concept 1, rip out the factory lead acid trailer batteries, and put in the smallest Tesla battery-maybe a used one?- if you had 50kWh of power in your trailer, you could run it like a house while boon docking (full A/C, etc). If you had a supercharging capability, you would be able to recharge it really fast.

2) Concept 2, go light with the trailer, but somehow tap into the Tow vehicle's battery with full current demand. it would reduce the radius you could go away from a supercharger to camp, but why even drag extra batteries in the trailer, when you have a massive 100kWh battery sitting right in your tow vehicle and able to be supercharged? My real problem is that I can't get to that energy except to move the vehicle. (not enough current capacity through the 12V trailer port to do anything except trickle charge trailer batteries, certainly not enough to run an inverter, etc.

3) Concept 3, I like the idea of regenerative brakes on the trailer, but I don't know how much weight they would add. And if they only charged the trailer batteries I am not sure how useful that would be. Still, it is overall energy on the system and if something like Prius regeneration brakes could be recycled from wrecks, maybe that would be cost effective for a science project. As currently plumbed though, excess energy in a trailer would present itself like a full battery to the Tesla's 12V trailer connector, and all that would do is stop the on board Tesla 12v battery from flowing current to the trailer (might charge the onboard tesla 12v if it needed it, but I am not sure of that-certainly would not feed back to the larger battery system -so you would have to chop into the guts of the Tesla for very very small returns.)
 

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