qjkxbmwvz

joined 1 year ago
[–] qjkxbmwvz@startrek.website 14 points 2 months ago (1 children)

One thing to keep in mind


the US is huge, both geographically and culturally. Flying from Los Angeles to Boston is further than London to Baghdad.

And likewise, the cultural "distance" between, say, New England or the Pacific Northwest and the deep south is extreme.

Of course there are things that affect (nearly) all Americans, but some context is important.

[–] qjkxbmwvz@startrek.website 4 points 2 months ago

But this applies to the UK, Ireland, France, Belgium, Italy, Spain, Portugal, and...well...much of the world, if these data are to be trusted.

[–] qjkxbmwvz@startrek.website 2 points 2 months ago (4 children)

But "included" doesn't mean free. You still paid for it.

[–] qjkxbmwvz@startrek.website 7 points 2 months ago

I'm curious how the battery percentage went up

Physicists hate this one weird trick...

[–] qjkxbmwvz@startrek.website 4 points 2 months ago

Is that true though? As in, is it really that dangerous? It seems that you'll dissipate power equal to the inefficiency times the nominal charging power, so something like 5V x 2A x inefficiency (inefficiency being 1-efficiency), which will probably be of order a watt.

I can use my car battery to charge itself without any issues


I just plug the red terminal to itself, and same with the black, which is to say, a battery is always connected in a way that "charges itself."

I think the key is that the battery probably isn't really playing a big role in OOP's setup


electricity doesn't "go through the battery," it just goes from the charging input to the power output circuits, with the additional power (due to inefficiency) being provided by the battery.

[–] qjkxbmwvz@startrek.website 46 points 2 months ago (7 children)

I'm not sure though


the power output and the charging input are both regulated and (almost certainly) current limited. So I think (not positive...) that you're basically dissipating your power in the inefficiency the charging and output circuits, with this power coming from the battery.

The inefficiency should (I think...) just be the round-trip inefficiency of the charging/discharging of your power bank


this should be way, way less than the short-circuit power dissipation.

The simplest toy model is to take a battery and try to charge itself. So you put jumpers on the + terminal and you connect those to the + terminal, and same for - (charging is + to +, NOT + to -). But this is silly because you've just attached a loop of wire to your terminals, which is equivalent to doing nothing. With charging circuits in between things get much more complicated, but I'm not sure if it goes full catastrophic short...

[–] qjkxbmwvz@startrek.website 17 points 2 months ago

For 75kg (roughly average South Korean male weight) and 7" step height (standard in the US I think, not sure about Korea), this is about 0.13kJ/step.

By coincidence, the human metabolic efficiency is (roughly) the same as the conversion between kJ and food (kilo)calories, meaning this would be (very roughly) 0.1 calories/step.

Not much, given a single French fry is maybe 5-10 calories. But it's better than nothing!

[–] qjkxbmwvz@startrek.website 8 points 3 months ago

Isn't universally funny.

[–] qjkxbmwvz@startrek.website 2 points 3 months ago (1 children)

Our home averaged 7.5kWh/day in December (we did not travel and we're home with family the entire time); this is about 10x less daily energy than the battery capacity of a modern EV.

Now, we have gas heating and stove/oven, so that adds a huge amount of load


but my numbers above are for 24hr energy, and batteries wouldn't need to supply that whole time.

Of course, this doesn't address cost, and it doesn't address natural resources, like you mentioned. But that actual required amount of energy per capita can certainly be achieved with current battery technology.

[–] qjkxbmwvz@startrek.website 9 points 3 months ago* (last edited 3 months ago) (1 children)

The exorbitant PG&E charges are usually "delivery charges," not the "generation charge" iirc. So we're paying reasonable rates for cheap, clean energy, but we're getting charged out the ass for getting the electricity to our home.

It sucks either way, but charging for delivery sucks more because on top of it all if we run solar and sell back to the grid we only get the generation charge (which is minimal). At least, that's my understanding


we don't currently have a home solar installation.

[–] qjkxbmwvz@startrek.website 8 points 3 months ago (2 children)

It's overpriced hardware

Have you seen the M4 benchmarks?

If you're memory bound then sure, you can get way more bang for your buck with Intel/AMD. But for pretty amazing CPU performance I think the "Apple is overpriced" trope isn't really true any more.

[–] qjkxbmwvz@startrek.website 20 points 3 months ago (5 children)

If you don't want to sail the high seas, and you don't want to pay, the library is a great, free option.

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