white exec wrote: 11 Feb 2019, 13:17
Can one Tesla partially charge another, I wonder?
No. No EV's that I'm aware of can currently be used to charge another EV with just a cable, at least not at any useful speed.
Although an EV with a nice large battery that could do this would make a lot of sense as an AA vehicle for broken down EV's that have run out of charge. Instead of towing a trailer with a large battery or generator on it, just share some charge from your own vehicle - enough to get the stranded motorist to the nearest charger to finish topping up.
If done at rapid charging speeds it would take less time than setting up the vehicle for towing and then towing it to a charger which is what happens now. Some EV's dictate flat bed towing only, which could be very expensive so a top up charge to get to the nearest charger would likely be a lot cheaper than being towed too, not to mention less embarrassing.
I remember there was some talk about being able to use electric vehicles as domestic power storage devices.
Vehicle to Grid is supported by a few EV's (not many) which allows a plugged in vehicle at your house to act as battery storage for the house to provide somewhere for solar (or off peak) power to be stored, and then used during peak hours to run the house or return some power to the grid, however it requires expensive equipment at the house and to be honest I can't ever see it catching on, for a variety of reasons I won't delve into here.
Vehicle to Grid doesn't support charging another car directly from one car to another on the side of the road, as the hardware required to do vehicle to grid is installed at a house.
Another option is that a very few EV's, mostly ones that are announced but aren't on the market yet, are offering a household 230v socket that is good for up to about 3kW - mainly offroad/utility vehicles like the Bollinger B1. The idea being that when you're out in the country with your offroad vehicle you can plug your power tools, beer fridge etc into the car...
In principle that could be used to charge another EV, however it would be very slow (3kW only adds about 12 miles of range per hour charging) and the EV owner would need a "granny charger" to make use of it - this is the unit that lets you plug into a normal 3 pin socket. Most EV drivers don't carry this with them in the car and instead leave it at home, as do I. Having said that, the petrol generator charging that Tesla would have only been providing 3kW at most as well!
The best advice is just "don't run out", if you do, currently you're looking at being towed somewhere where you can be charged.
Hasn't happened to me yet in 24k miles and two years of driving and stretching my luck a few times. I have come very close once though!