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Apr 2, 2019 at 3:39 comment added forest @VolkerSiegel If voltage is too low and the computer doesn't shut itself off when it hits the cutoff voltage, then you can absolutely damage it. It can cause an unstable clock which alone can cause damage.
Apr 1, 2019 at 20:04 comment added Mark Zinc wouldn't have been available in ancient Sumer. You're looking at 9th-century India at the earliest; before that, zinc ore was smelted directly with copper to produce brass.
Apr 1, 2019 at 19:57 comment added Aubreal @reirab Youtuber/Medieval historian Skallagrim made a good video debunking the "fantasy" of becoming king within days all thanks to modern weaponry.
Apr 1, 2019 at 15:13 comment added frarugi87 @reirab I know, it was sort of a joke ;)
Apr 1, 2019 at 15:10 comment added reirab @frarugi87 Because otherwise you'll deplete your battery quickly as your phone searches in vain for a signal.
Apr 1, 2019 at 12:19 comment added Luaan @reirab People don't just wait patiently while you murder them with advanced weaponry. Those are warriors, not random civilians. Modern weapons make you very dangerous on a battlefield (if you have the training), but they will not prevent other people from killing (or detaining) you. Why do people always imagine the spearmen in Civilization killing the tank by running all the way to the tank and striking with their spear? You don't attack where the enemy is strong :)
Apr 1, 2019 at 11:47 comment added frarugi87 Why airplane mode? In the medieval europe mobile phones on planes were not restricted...
Apr 1, 2019 at 4:28 comment added reirab Regarding the first point of things they need, this is actually probably one of the easier parts of this problem to solve, provided you can get access to modern weaponry. Take several assault rifles per person, plenty of ammo, and sufficient amounts of spare parts of maintenance gear. 13th century tech will be no match for you. If you want, you can become the king probably within a matter of days. You will then have plenty of servants and guards. The tech would be so far beyond them that you could probably take the throne with the mere threat of force without actually hurting anyone.
Mar 31, 2019 at 21:21 comment added Volker Siegel @JBH I do not want to annoy you. Let's see it as a discussion of facts - not about being "right". No need to answer this, and we can delete these comments if you like. Now, I have some physics background, and I will explain what I think, and why. Laptops need to accept uncontrolled low voltage without breaking because a dirty connector or partly broken cable of the power supply can create any low voltage when it has a high resistance. Of course the laptop may crash. Lemon batteries behave just the same as alkaline, only that they have a higher voltage per cell, an a much higher capacity.
Mar 31, 2019 at 7:47 comment added JBH @VolkerSiegel Modern laptops are not transistor radios, they can be damaged by uncontrolled low voltage (modern electronics expect the power to be on or off, not something in between). And we're not talking about alkaline batteries (which will void your warranty), we're talking about lemons and sea water. It's like being told by someone who's read a book about trapeze that if a trapeze artist can make it through one show without a net, the nets aren't needed. My end of this conversation is over.
Mar 31, 2019 at 6:31 comment added Volker Siegel @JBH Sure the current draw is dynamic. But that is no problem, it just means the battery needs to support the highest load. For increasing current, the voltage always drops. If it drops too low, the battery is too small, "not strong enough" or "empty". The battery just needs to support the highest required current, that's all. There is no need for a control circuit. A normal laptop battery does require a regulator for charging. You can certainly power a laptop from a set of common alkaline cells, without control circuit.
Mar 31, 2019 at 2:51 comment added JBH @VolkerSiegel, modern electronics draws electricity (amperage) dynamically. The power supply is designed to compensate for those changes in demand by regulating the voltage (to keep it stable). It requires transistors. Without that control circuitry, the dynamic draws will cause the voltage of the "batteries" to change - shutting the laptop down in the best case, damaging the laptop in the worst case.
Mar 31, 2019 at 0:35 comment added Volker Siegel @JBH I do believe you. And it would take something on the order of 10000 cells, but they are not complex. I do not understand the point about "uncontrolled", though. It is not easy to scale it up to run multiple laptops continuously, I should have pointed that out. It's not portable at all, more like multiple buildings filled with stacked cells. The loss in the wiring is a problem - but that means just some more cells. Solar cells as proposed are easier of course, but can not be replaced when lost. Sulfuric acid, resistant containers or regulators are not needed, I think.
Mar 31, 2019 at 0:05 comment added JBH @VolkerSiegel, You're talking to an EE. Salt water makes for an amazingly weak battery. Putting batteries in parallel will reduce the intrinsic resistance (and increase the available amperage at the induced voltage), but it's uncontrolled. and it takes a lot of lemons (and even more salt water) to create a battery that would run a laptop for more than minutes. If you don't believe me, give it a try.
Mar 30, 2019 at 23:08 history edited LSerni CC BY-SA 4.0
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Mar 30, 2019 at 23:06 comment added Volker Siegel @JBH You do not need lemons, just any electrolyte. Like salt water. The lemon just makes it a very good demonstration experiment. The lemon also holds the electrodes mechanically in place, but putting salt water into a bowl of some kind is good enough. Also important may be that you do not need qualified labor to build the batteries. The internal resistance is reduced by using it in parallel.
Mar 30, 2019 at 22:53 comment added JBH @VolkerSiegel, getting electricity is easy. Getting enough controlled electricity to run a laptop isn't. If you had consistent year-round access to lemons (their regular cultivation in Italy didn't occur until the 1400s), you'd still not be able to run a laptop for more than a few minutes no matter how you chain the lemons together (too much intrinsic resistance). If the travelers had the lacquer tech from Japan they might create rudimentary water turbines - maybe. (and then there's the need for regulators and limiters... ugh.)
Mar 30, 2019 at 21:59 comment added Volker Siegel Getting electrical power is much easier: See en.wikipedia.org/wiki/Lemon_battery You only need zinc and copper! More voltage by using batteries in series, more current in parallel - so use multiple chains of batteries. That gives you DC (direct current), AC would be much more complicated.
Mar 30, 2019 at 20:41 history answered LSerni CC BY-SA 4.0