He's saying if you plug the charger in it can transmute the energy into work, meaning when you exit the room you may come back to finding it sitting on the counter unplugged. As your partner wouldnt have wanted it to put a hole in the roof so they unplugged it and put it on the counter.
Is that why they're so inaccurate that they always die around 20-30% and never charge to 100%? I figure that phone battery meters are accurate cause they can track usage habits, but how would you do something like that with a power bank?
Yep. State of charge is almost entirely voltage based.
As a battery loses charge, the voltage sags.
What's happening in the OP is that the batteries are getting a voltage bump, likely from the conversion to/from 5v on the output and the conversion back to battery charging voltage on the input (or the thermal/internal resistance is changing).... One of those things.
Either way, the conversions are not 100% efficient, so basically all this does is turn your battery bank into a heater, slowly sapping the power away from it as heat until dead.
With phones, it can also be battery degradation, that the voltage drops off at a higher "state of charge" level than when the battery is new.
Voltage sags can also be induced by load. If you go from a high drain state on your phone to a low drain state (say, going from playing a 3D mobile app to idling at the lock screen) the state of charge % can actually increase.
Cold temperatures can also increase the internal resistance and cause batteries that are not fully discharged to stop operating as well, only to work again after being warmed up.
Current battery tech is wild, and the state of charge indicator of voltage can be extremely inaccurate.
I wonder by what method it does that? put out a pulse code on the power out and look for it? Some USB cables don't actually carry the data lines through, so.
You either have a ping before connecting and if you get a response don't do it. Or you send some high frequency wave additionally to the power. You can detect that signal and then stop accepting the power.
Probably just sends a number as data, and if it gets it back then doesn't charge.
You're right that some cables don't carry data, but most do and as long as the cable that comes with it does then it's going to be fine for 99% of cases.
There'll often be a way to break it like going through a USB hub, but most people aren't actively trying to damage things. I can see people wrapping the cable around it and plugging both ends in to stop them flapping about though.
They are cheap and if you don't need an expensive product, they are mostly fine, but I got a free powerbank with some crappy teen magazine (when I still ocasionaly read those ad filled pieces of shit) and it died on the second charge.
Assuming it was either 15 years ago or your powerbank is a budget one.
My powerbank would just flip me off and tell me to go fuck myself if I did plug it into itself.
(seriously tho, it would just cut power and turn off immediately. If your powerbank doesn't do at least that, then discard it and get another one with more advanced protection features)
You shouldn't charge a battery pack at the same time you're discharging it unless it's specifically designed to allow that. Most consumer power banks are not designed to do that.
I once charged my phone by holding it over an induction cooktop. Only for a couple of seconds though as I was afraid to fry my phone, but it did it over 40cm
Yeah, I had the exact same thoughts about the risk to the phone, but curiosity got the best of me. The phone worked fine for several years afterwards so no harm done.
I used to take those 9-volt battery connectors, wire them up together and then recharge a dead 9-volt with a brand new one until the tester strip thing showed they were both even. Surprised they never popped because they would get really hot lol
Those chargers are really dangerous. It is technically possible to recharge a disposable alkaline battery a few times, but you're never going to get more than a half charge, and it will fuck up the internal chemistry turning each battery into a tiny potential pipe bomb.