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Comment by jstanley | Hacker News Reader

Do you really want the grid taking energy out of your car when it needs it?

Would you want petrol stations siphoning fuel out of your car when they are running low?

That seems pretty alarmist.

This system hasn't been implemented yet, but when it is, I'm sure electric vehicle owners will be able to set the conditions at which they push energy onto the grid: electric price > $X, only drain battery to Y%, etc.

If you gave me $3 for the gallon of gas I bought yesterday for $2, I would sell it if I had 10 gallons in my tank

Even better, a very similar system is currently being implemented by Tesla (under the name Tesla Virtual Power Plant). It's for their Powerwall product rather than the cars, but I think it's safe to assume they'd design a similar system for their cars.

It looks like the Virtual Power Plant program lets you configure a backup reserve, so you can choose how much of the capacity you keep for yourself and only push a small portion of the battery's capacity to the grid.

Yes. Because it means fewer peaker power stations need to be built. And I care a hell of a lot more about that than whether my battery is at 86% or 94% when I wake up or get out of work.

Why not, as long as I got paid for it?

Because you'll get back to your car to find that its tank is empty and you can't drive anywhere. They'd have to pay a substantial premium for that to be worthwhile.

I mean obviously there would be some kind of floor in terms of how much range you are willing to be left with. If you're willing to discharge your car lower, you can take greater advantage of arbitrage opportunities, but obviously your car could be lower at any point in time.

You can control how much is given to the grid, and say that e.g. it has to have 60%+ left at all times.

There's no need to keep cars charged to 100% all the time. They already have batteries that are overkill for daily commutes, and if you suddenly need to make a long trip, you can top it up in 20 minutes from a highway charger.

BTW, on the Internet there's always some guy who just has to have a 500-mile daily commute while towing a boat, through a desert, in snow, uphill both ways. That's fine, they can opt out.

Note that the charging connector isn't a dumb plug like a household appliance. It has a two-way communication protocol that negotiates all of the parameters.

It won't drain below X% and will charge when below Y%

Potentially draining down the battery down to 80%

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