1: No this incorrect and shows a complete lack of understanding on thermodynamics and electrochemistry.
LOL
Did you feel superior now after puffing up your ego by including those disparaging personal remarks along with your disagreement?
You couldn't just disagree with the facts presented and explain why in a mature manner like Harlow?
You can follow the link in my sig to see if I might have a "complete" lack of understanding in those areas.
Okay my bad. I should not have said "all" batteries but it is absolutely true about some, such as lead acid batteries. As for Lithium Ion, I note the charging rate does indeed slow down for most devices as they near full charge, including with laptops, cell phone and even EVs, much in part, by design - as explained here,
Why Do Smartphones Charge So Much Slower as the Battery Nears Full? And
Why Do Electric Cars Charge Slower After 80% Full? (Explained).
Yes, I understand Ohm's Law very well. A charger, regardless if rated at 100A or 100mA, still needs to output a voltage slightly above the battery's voltage rating or else the battery will never become fully charged.
As for the speed of light, we simply said the same thing from different aspects. The faster an object goes, its mass gets bigger. As it gets bigger it slows down UNLESS (as you noted) you apply more energy. Add more energy, it goes faster, gets closer to the speed of light, but again increases in mass requiring even more energy just to maintain that speed. Each time, these recurring cycles of faster speeds/larger mass/increased energy requirements result in smaller and smaller increments in acceleration and therefore AS I SAID, the
rate of acceleration slows down and the actual speed of light is never obtained. At least not until warp drive becomes reality.
So, when I said above,
Since our rate of acceleration slows down the closer we get to the speed of light, we can never quite reach it (at least not until we learn to break some laws of physics).
and despite your claim, that is absolutely true - as anyone who really did study high-school physics would know.
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For a "power supply", you can ALWAYs use a supply rated at a higher current value, but never lower.
I choose to differ. Sometimes you CAN use a laptop supply with a
lower current rating.
You took my statement out of context. As a general statement, my assertion is correct. Are there exceptions? Of course, but exceptions don't make the rule, nor do they make the general statement incorrect.
The second sentence in that same paragraph is important. I said,
Now, about current. For a "power supply", you can ALWAYs use a supply rated at a higher current value, but never lower. If lower, the device may try to demand more power than the supply is capable of delivering. Not good.
Okay, my bad. Perhaps just saying "never" was the wrong phrasing as that implies an absolute - no exceptions. You are right and "sometimes" you can - but IMO, it would be unwise because, as I said, the device "may" demand more than the supply can deliver. So I should have used a qualifier and said, "you
should never use a lower value current rating". But please note I further explained why you should not go smaller by stating,
it MUST have a current capability to support charging AND operate the laptop at the same time.
If the supply is ONLY being used to operate the laptop and is NOT also being used to charge a discharged battery too, then sure, a smaller (if not too small) power supply will "probably" work without issues - assuming the correct voltage. But one really should have a good understanding of the actual power requirements before using a lower capacity (underpowered) supply. Yes, with the right gearing, you can probably tow a 40 foot, 20,000 pound trailer with a Honda, but should you? Would you worry about overheating, sufficient braking, and other stresses? I hope so.
If your laptop came with a 100W supply, I would be very leery, and advise against the use of a 65W supply. 35% less capacity is a lot. Running just the laptop "may" be okay, but I would make sure the battery has been removed first. If lucky, at worse the laptop would just crash and recover fully upon booting with a suitable supply. But if unlucky a crash could result in file corruption, or perhaps worse. I would also pay close attention to the temperature of the power block to make sure it has lots of ventilation to avoid it getting too hot.
none of them had a "19V battery". Instead, the batteries came in a range of lower voltages, usually in multiples of 3.6V or 3.7V, the 'nominal' terminal voltage of an 18650 Lithium cell.
Now wait! There may be a misunderstanding for some reading here between the definition of a "cell" and a "battery". The words are often used interchangeably but do not always mean the same.
Harlow is absolutely correct about the way designers strap cells to make "a" (as in 1) battery of the desired voltage and current capability.
My bad again for not being more detailed. Frankly, I didn't want to get too tangled up in unnecessary complexity and detail I feel is not really needed (or even appropriate) for this thread. My post was already getting too long.
Anyway, to add and illustrate, if you take a single, standard
AA battery, that is indeed a "battery". A (as in one) 1.5V battery.
But what if your flashlight, for example, requires 4 AA batteries, arranged in series? Now that single AA battery becomes a "cell" - 1 of 4 cells that make up a single 6V battery. When arranged in series, the voltages add, but the capacity remains the same.
If you take those same 4 individual AA batteries and arrange (strap) them all in parallel, you end up a single 1.5V battery (of 4 cells) but now the capacity increases.
If you take those 4 individual batteries, and strap two pairs in parallel, and then the strapped pairs in series you have one 3V battery, made up of 4 cells.
A single Li-Ion battery is made up of multiple individual cells in the same manner. They are strapped in various series, parallel and series-parallel configurations until they total the desired voltage and current capability the designers are seeking.
I note the Tesla Model 2 battery contains 7,104 cells!
Having said all that, my point remains the same. Regardless the type and how the individual "cells" are arranged, the end result for the "battery" is what matters. The charger's output voltage should be rated for the voltage of the battery. If the laptop came with a 19V charger, a 10.5V charger would NOT be a suitable replacement for that battery. Nor would a 24V charger.
Now - to complicate matters, as I noted above, there is a difference in the functions of a computer power supply (even those for laptops) and a laptop battery charger - even when the same devices as the supply. Do note that the RAM, drives, CPUs, GPUs, fans, USB ports, etc. in laptops operate with the same voltages as those used in PCs. So within the laptop, the voltages are split and divided into standard voltages, typically +5 and +12, and then again to lower voltages.
So while the battery may be designed for 19V, the laptop (the computer) itself may be designed to operate with a different voltage, say a 16V power supply, or even a range of inputs and the laptop's power circuits deal with the distribution accordingly. I just have not seen a laptop where the manufacturer's specs state a range of power supply voltages. But just because I have not, that does not mean they don't exist.