
Tesla adds bidirectional charging capability - Corrado
https://electrek.co/2020/05/19/tesla-bidirectional-charging-ready-game-changing-features/
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_ph_
Before we investigate complex power to grid schemes - though electric cars
could have quite an impact there - it would be great if any electric car came
with at least one power outlet, so that you could power critical appliances in
your house during a power outage at least. Like keeping the fridge running,
some lighting and heating food on a small cooker. The same would also be great
for any kind of camping.

Beyond that, electric cars could of course have a huge contribution to the
grid, especially with high percentages of solar and wind power. The first step
would be to charge the cars dependent on the power supply situation. Loading
during peak production and not loading in times with low production or pausing
it in times of demand peaks.

The final step would be using them to feed power back to the grid, though this
needs to be done carefully, as this would increase the wear on the battery.

~~~
new_realist
Powering critical appliances with your car during an electricity outage is
tricky: if the outage lasts for an unexpectedly long time, you end up with no
power _and_ stranded at home with a car that has no miles in the tank.

Meanwhile, you can buy a generator for as little as $400.

~~~
Someone1234
$400 generators cannot run large home appliances as the initial wattage surge
during startup will overload them and cause the breaker to fire.

For example, a fridge-freezer might need only 600 watts to run but will also
need up to 2000~2500 watts to start. You'll struggle to find a $400 generator
at 2K+ watts capacity, even if that load is only for ten seconds. Maybe "own-
brand" generators from e.g. Harbor Freight, but would you trust it?

And that's just for a single appliance, large space heating/cooling systems
are even more problematic/spikey. Buying generators for your home is actually
more expensive and complicated than many people realize.

You'll quickly find yourself looking at $5K Honda inverter generators w/7K
watt capacity even if that seemed overkill at the outset.

~~~
thedrbrian
How big is your fridge / freezer. Just looked up the specs of my freezer and
it claims to use 170kwh per year or about 19 watts an hour. Excluding my
gaming pc , 600w continuous would power my whole house.

~~~
xsmasher
The fridge doesn't run continuously, so "needs 600w to run the motor" and
"only uses 19w an hour" can both be true.

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new_realist
Vehicle to grid is only 80% efficient and prematurely wears the battery.

Given that utility scale solar is much cheaper than residential solar, I
wouldn’t be surprised if utility scale energy storage is also cheaper than
vehicle storage.

Lithium ion is optimized to be light, which is not an requirement for grid
storage, which could make use of molten salt, pumped hydro, compressed air, or
hydrogen electrolysis.

~~~
slashdotdash
Vehicle to grid may actually improve battery health and keep them healthier
for longer.

> “This new research into the potentials of V2G shows that it could actually
> improve vehicle battery life by around ten percent over a year.”

This requires intelligent usage where the battery state of charge is kept
within a limited window, not fully charged or drained.

[1]
[https://warwick.ac.uk/newsandevents/pressreleases/clean_ener...](https://warwick.ac.uk/newsandevents/pressreleases/clean_energy_stored/)

[2]
[https://www.sciencedirect.com/science/article/pii/S036054421...](https://www.sciencedirect.com/science/article/pii/S0360544217306825)

~~~
new_realist
I don’t think reducing the effective range of your car to preserve battery
life will be very popular; people want the freedom to drive as far as they
can, because it’s hard to predict when they will need that capability, and
charging is very slow. If someone does have a very predictable routine they
can just not overcharge their car in the first place and save the discharge
wear.

~~~
magicalhippo
> people want the freedom to drive as far as they can, because it’s hard to
> predict when they will need that capability, and charging is very slow

For most people, if they really need to drive hundreds of miles unexpectedly,
I doubt spending 15 minutes at a high-speed charger to top up the batteries
will be an issue.

~~~
new_realist
As someone who drives an EV, I can tell you that it’s not the long distance
trips, it’s having an unexpectedly busy day of errands in cold weather that
gets you—realizing that you’re starting out at only 50% charge, which means
you can’t make that last trip into the suburbs at the end of the day. There
are very few fast chargers in densely populated areas and they’re often
malfunctioning, or have queues. They also hurt your battery, so not to be used
on a regular basis.

~~~
speedgoose
In Norway where chargers are a lot more common, it's not an issue. Of course
if I want to charge at 4pm at a popular place it may be a queue but most of
the times many chargers are available and functional.

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sorenjan
It would be nice to be able to charge a car from another car, so you can help
somebody that has depleted their battery at the side of the road.

~~~
netcan
...especially considering that you can't just go buy them some petrol.

Now that I think of it, what's the MO if you run out of juice in a tesla..
tow?

~~~
pmorici
You call Tesla's roadside assistance and they take your vehicle to the nearest
supercharger. Depending on how dead the battery is there is a procedure to
attach an emergency power source to the leads on the cap of the tow hook cover
to let you get the car into neutral to get it on the truck.

~~~
shaftway
I've seen a Model S rolled off the back of a flatbed at a charging station.
They ran out 10 miles from the next supercharger. Took them a while to figure
out how to get power to it just to open the charging door.

------
loceng
I'd highly recommend this "Battery Day is Coming" 40 minute video that
explains what Tesla is likely planning:
[https://www.youtube.com/watch?v=pP971PYzQJs](https://www.youtube.com/watch?v=pP971PYzQJs)

In one part of it they explain that how the batteries that went to stabilize
the grid in Austrailia (and saved them a lot of money immediately, their
investment/cost paid back in a few months from my understanding) can be
decentralized to all cities around the world with using vehicles as the
storage for energy at non-peak hours and source of energy during peak hours -
arguably when you've driven your vehicle to the city and where production and
office space, businesses serving the area, will be needing more energy.

------
spectrum1234
This is going to make electric cars extremely cheap once the million mile
battery is out. Probably at least 50% cheaper given the money you can make
selling off peak electricity at peak prices.

Electricity costs by me since I switched to time of use are 4x as much on peak
vs off. My Tesla costs about $6 for a full charge off peak. It seems like its
easy to make (4-1)* 6 = $18 a day off of this the car as it home. Let's say
$10 after conversion loss and battery wear, etc.

Once you buy any other hardware needed (I think they are $2k-4k now), this
seems like free money. Worst case, car is home during peak 2 days a week and
$10/day gain, $4k system: 2.5 year payback period and then $223/month income
Best case, car is home during peak 5 days a week and $15/day gain $2k system:
26 week payback period and then $322/month income.

The best case over 10 years is worth $38,700.

However the biggest opportunity here is probably for Tesla to lease the
battery to consumers. The car will be discounted significantly if you can plug
in 3 days a week near peak usage.

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gregwebs
There was a recent discussion on HN about using a Tesla as a store of energy
that could be tapped to help with emergency power scenarios:
[https://news.ycombinator.com/item?id=23178733](https://news.ycombinator.com/item?id=23178733)

Apparently the capability is already there!

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thdrdt
The Xpeng P7 also has a 220V output.

I guess this can be useful for a lot of things.

[https://en.xiaopeng.com/p7/configuration.html](https://en.xiaopeng.com/p7/configuration.html)

(Also a great looking car imho)

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lacion
the whole point behind Vehicle to grid is not to sustain your house but to
stabilize the grid at peaks, don't think as your car but as the whole fleet of
electric cars able to do V2G, that means that the grid could use a bunch of
cars to sustain a small peak and avoid the need altogether of very expensive
peaker plants

------
raxxorrax
The term is pretty misleading if cars are still charged with AC current, even
with a rectifier immediately after the power supply. Maybe it is a language
thing.

Otherwise this "technology" could indeed be quite useful to lessen load. I
would have thought that maybe providing local power to your home instead of
buffering the whole network would maybe be more practical.

~~~
teraflop
I don't see what's misleading about it. AC vs. DC has nothing to do with which
direction _power_ is flowing, which is what they're talking about.

And feeding power to the "grid" is actually quite straightforward, at least
for the customer's equipment. In effect, you can think of the 60Hz
oscillations of AC voltage as being like an enormous rotating crankshaft that
each customer is tightly coupled to. Correctly applying a "torque" to that
system automatically distributes the energy where it's needed.

In contrast, de-coupling and re-coupling one house with the grid on demand is
a lot more complex: you lose the stabilizing effect of the grid's enormous
"inertia", and you have to carefully synchronize the phases when
reestablishing the connection.

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gwbas1c
When I plug my car in, I expect it to charge. When I get in my car, I expect
it to have a full charge. I don't want to have to push a special button or dig
into hidden menus just to ensure that my car actually has a full charge.

This is critical for when I take a long road trip, and I expect that I have a
full charge when I leave.

What I think makes sense is temporally stopping charging for the 10 seconds it
takes for a generator to spin up. But these kind of events should be so
infrequent that they have no noticeable impact to my ability to start a road
trip with a full charge.

~~~
wcoenen
> _When I get in my car, I expect it to have a full charge. I don 't want to
> have to push a special button or dig into hidden menus just to ensure that
> my car actually has a full charge._

Then don't buy a Tesla, because the default factory setting is to charge to
90% to reduce battery degradation.

(Personally I like that feature, I wish I could configure my phone to make the
battery last a year longer.)

~~~
hnarn
iPhones kind of do this, I was surprised when I bought one recently and
noticed it. It assumes your wake up time from usage patterns and then avoids
charging above 80% or something during the night until right before you wake
up.

