What about useing technology to solve this problem? Right now if you run out of petrol, they send a tow-truck or a flat-bed with a 5 galon tank of gas. Why not have some sort of truck-with-a-battery than can provide ~30miles (10%ish) recharge.
It's a legitimate issue that you may take a detour--forced or by erroneous navigation--and so you might end up a bit short for whatever reason (that's not an issue specivic to ev/tesla). And it seems unrealistic to call the driver (any driver) 'stupid' 'ignorant' 'not worth of the car' ... which are basically lazy ad-hominem attacks. The issues is well understood by peole of experience in actual long-distance navigation.
Terrible back-of-the-envelope math disregarding any kind of loss or inefficiency, and assuming a magical DC->DC power system which would convert a car's 14.4V alternator source to something suitable to charge a Tesla without losing anything:
A "normal" modern car's alternator can put out ~100 amps at 14.4VDC. That's a maximum of about 1.5kW, which will charge a Tesla at a rate of about 2 miles of driving per hour of charging, again assuming a magical efficiency.
The reality is that the car's own systems take at least a few hundred watts and alternators aren't built to run at maximum load all the time and are likely to fail after a while running near capacity. Plus, the Tesla doesn't, to the best of my knowledge, contain any sort of DC->DC hardware capable of bringing 14.4V up to the necessary charge voltage, and even if it did losses would be at least on the order of tenths.
So, even with a good, running car and a theoretical alternator, you'd be waiting a very long time next to the running car (and burning a lot of gas) before your Tesla would go anywhere.
Obviously it would be possible to build, for example, a tow truck with much greater charging capacity and as time goes on we'll probably see at least a few of those in real life. But the fact remains that gasoline provides an excellent energy density in a convenient liquid form and that for certain edge cases, its conveniences will be hard to beat.
Come to think about it--the easiest hack-- is just a piggback battery. Lets say the Tesla power-source is 500 pounds. 1/10th would be 50 pounds. Assuming replacement of the battery is $15K at cost, that would be a $1500 asset. 4x of them would add ~$6K per charging depot (<~5% of planned capital outlay). Transport to site by 3rd pary service using a pickup truck (ie, no fancy gear needed).
Volumne would be the size of a a carry-on wheelie bag. The engineering solution would be to have a second charging point internal to the passenger/trunk--perhaps in the 2.0 version of the Tesla models currently on the board. The only engineering consideration would be that the li-ion powertrain would need to operate during charge (like a laptop or cell phone) but would presumably overcome.
That's an interesting idea, although I think it'd be hard to make a piggyback battery pack light enough. The Tesla's swappable battery pack module including frame/supports, armor, and coolant weighs over 1,300lb.
Nobody wants lithium batteries in their passenger compartment, but I do suspect it might be possible to make a ~200lb pack that would fit in a Tesla's frunk and move it at least a few miles. Thermal management would be a tremendous challenge in that area unless the "auxiliary battery" port could somehow interface safely with the car's existing liquid cooling system.
Even 20kW will only get you 40-50 miles per hour of charging a Tesla.
The Volt weighs an entire thousand pounds less than the Tesla, and it gets a much better watts-to-mile ratio. Even then, the Volt's generator is all the way up in the 55kW range.
That's a far cry from gas or diesel, where a five gallon can can be transported by a friend in any vehicle, poured into any car in a matter of minutes, and will get you 100-200 miles.
Towing to the nearest fixed rapid charging station seems more practical than the generator vehicle in many cases, provided tow companies will tow the vehicle.
One interesting idea might be for Tesla to provide a "towing mode" that raises the ground clearance as the batteries are dying in order to make it easier to load the car onto a flatbed - that, along with education of tow companies, could be very beneficial to improving the outcome of these "stranding" situations.
You only have a couple of kilowatts of power output from a large alternator. So you would have to run the car for quite a long time to get much charge (I guess it wouldn't be so bad to get 10 miles of range that way though).
It's a legitimate issue that you may take a detour--forced or by erroneous navigation--and so you might end up a bit short for whatever reason (that's not an issue specivic to ev/tesla). And it seems unrealistic to call the driver (any driver) 'stupid' 'ignorant' 'not worth of the car' ... which are basically lazy ad-hominem attacks. The issues is well understood by peole of experience in actual long-distance navigation.