Comment by smileysteve | Hacker News Reader

Comment by smileysteve | Hacker News Reader

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> aren't prepared for everyone to come home at 5 and plug in their cars.

200 mile range cars and 20 mile average commutes make this not a necessity. The need to use fast charging even less, as slow charging from 5pm-5am provides more than enough miles for the average commute.

I wonder what your electrician thinks about HVAC systems? They all do turn on at roughly the same time (a top cause of brownouts in under prepared grids), don't have a slow charging equivalent (they even depend on large capacitors to start the compressors). The even worse case is a house with multiple heat pumps and auxiliary heating.

Or what does your electrician think about hot water heaters? Fast charging requires similar supply as every house coming home and taking a shower at 5pm.

Or, perhaps the most likely, every house starting the oven at 5pm, the stove, The microwave, With some hot water.

What about all of these combined?

Information; on circuit breaker size required

Low speed charger 120x15amp

Highest speed residential charger: 240x40amp

Water heater 240x30amp

Instant whole house hot water heater 240x40

HVAC 240x30

Aux heat 240x30

Stove 240x30

Oven 240x30

Microwave 120x15

I think the parents post is claiming that the grid isn’t able to handle the additional load of charging everyone’s car at the same time on top of the stoves etc that you mention. It will be in addition to not instead.

Not only is it a solved problem (Tesla, grid.io, ecobee, nest have time of use, if not community savings) but it is solved by electric car batteries preferring slow charge, electric cars having range beyond daily commutes, some people charging their cars at commercial connections some of the time, and everybody not having the exact same schedule.

> (they even depend on large capacitors to start the compressors).

Those are starting caps and have nothing to do with energy storage. The caps cause a lagging in the voltage to cause a phase shift in the starting winding relative to the running winding which gets the rotor spinning. Once it gets up to speed it disengages.

What I see are lots of people comparing charging loads to existing appliances but not the fact they these loads are in ADDITION. So we are still facing a large increase in electrical load.

> these loads are in ADDITION.

If, every household drives 200 miles a day

If, those households fast charge at home instead of the commercial charging network that popular commercial entities have been installing (malls, gas stations, supercharger network)

If the lithium ion batteries are fast charging with no pausing.

If the modern electric car (or HVAC) doesn't pay attention to the rate plan that is based on grid capacity (they do)

Tldr; If everybody connected to the same substation gets home at precisely the same time from a 200+ mile road trip, while the day is at its hottest, preheats the oven, takes a shower, and manually turns down their dumb thermostat, and schedules their car to rapid charge to drive another 200 miles in a few hours, Then yes, the grid and individual house would have major problems. But this is obviously a straw man.

There are starting capacitors and running capacitors; the start ones do provide "storage" for initial energizing of the compressor. Yes, the starting one does disengage after start.

But, if we're arguing the semantics of HVAC, we should also argue the semantics of car chargers. They don't jump straight to fast charging on plug-in. They negotiate with the car, checking battery levels, first cooling the battery pack, then, chooses between fast charge and slow charge based on state of the batteries (and optional user input), it also checks with your utility rate plan to see if it's optimal to charge.

> There are starting capacitors and running capacitors;

Not all single phase motors are cap start/run motors.

> the start ones do provide "storage" for initial energizing of the compressor.

No, they are phase shifting.

All teslas besides the SR Model 3 charge at 48A. At home with the Tesla wall connector, it’s a 240V charger, so roughly 11k watts, and they recommend a 60A breaker.

All Teslas will charge at whatever rate the EVSE says it's rated for. If you have a 36A EVSE it'll pull 36A. You don't have to have it set to 48A, you don't need a 60A circuit to charge a Tesla.

Yes you are correct. I guess I was just stating that it can pull up to 48A, which can be a lot higher than most other appliances in a home.

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