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Comment by theli0nheart | Hacker News Reader

> For electric cars, no-one needs 48A (11.5kw) charging (unless you bought a hummer EV and then you’re an idiot). The city can start denying permits for charging at more than 24-32A unless you have enough battery storage to cover it up.

You're wrong about this. We frequently take day trips that are about an hour each way from home, and without the L2 we would get dangerously low after another day of commuter driving. As a co-poster noted, standard chargers will take days to recharge. Ours does about 6 miles of charge / hour, whereas the L2 does about 30 miles of charge / hour.

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Which is why the OP includes 32A=7.7kw charging, which is what Tesla's get. OP is only really against insane installations where you charge at 48A=11.5kw, that's the capacity of 1.5 Teslas, and is only really necessary when you're running a horribly inefficient Hummer EV (200 kwh battery getting 350 miles EPA range means it's operating about 600 wh/mile or 1.6 miles per kwh, twice the energy usage of a Model X).

One option is to have charging speed limits based on state-of-charge.

Maybe charging after your daily driving only charges at 3 kW, but charging after a road trip does the full 11.5 kW.

But yeah, I've certainly come home from a road trip with 10% battery, plugged into my 11 kW home charger, and had it say it would take 5 hours to recharge to my 70% limit. If I was only charging at 2 kW, an overnight charge wouldn't get me very far the next day.

But how often do you need to go far the next day? If you come home with 10% charge (30 miles), and then plug in for 10 hours and add another 40 miles, is that not enough for work and errands the next day?

I don't know about you, but I mostly do long trips on the weekend. As long as I have enough to get to work Monday morning and am full by the weekend, that's almost always good enough for me.

The average commute distance is 41 miles, 10 hours of slow charge is a net loss.

"Frequency" matters significantly here, while charging at home is an extreme convenience, you might expect to stop at a charging station if you fall out of bounds, like with a 250 mile trip 1 day and a 100 mile commute the next day (each without a charging stop connected with any bio breaks)

It's definitely something Tesla has solved for to achieve their cross nation road trip planning with 0 home charging.

What kind of vehicle & miles do you have where 24A charging isn't enough?

A 7.2kw level 2 charger using 32A is pretty standard, 24A would be slower than I'd want for daily use, and I own an older Leaf. Even at 32A, it's slow when you need to charge quick for any reason (top off for afternoon errands, etc).

I have a 320 mile range, so I never need to top off for afternoon errands.

Naively you'd think that cars with a larger battery would be more likely to need a level 2 charger since it takes so much longer to charge a large battery on L1 than it does a small battery. But in fact it's often the opposite -- a big battery means you only need enough charger to handle an average day rather than a peak day.

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