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  • 226 Comments
Joined 1 年前
Cake day: 2024年2月1日
  • qjkxbmwvz@startrek.websitetoAsklemmy@lemmy.ml•To what extent is this accurate?
    1·
    1 个月前

    The amount of money you save (and invest) isn’t accurately depicted with this though. Living expenses don’t necessarily grow with take home, if you keep lifestyle creep to a minimum.

    So what this means is that if you make $100k and save $10k/year, if you start making $200k you can save the same $10k/year, plus the entire additional $100k after taxes (let’s just say that’s $50k+). So you doubled your salary but your savings went up 6x+.

  • qjkxbmwvz@startrek.websitetoFunny@sh.itjust.works•Infinite energy trick
    41·
    1 个月前

    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.websitetoFunny@sh.itjust.works•Infinite energy trick
    451·
    1 个月前

    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.websitetoFunny@sh.itjust.works•Ever been judged by a floor?
    17·
    2 个月前

    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!