# eli5: How do phones “pull” electricity?

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I could be totally wrong about my understanding but I think phones and other devices “pull” the electricity needed to charge their batteries and if you plugged it into a wall plug that couldn’t supply enough juice it could damage the phone. I also hear people talk about some wall plugs charge their phone way faster so my question is can phones or other devices modulate how much they pull if they detect that a plug is capable of supplying more? Enlighten me people of the internet’s!

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no, electricity is pushed into the phone, and can damage it if too much is pushed.

some phones can take more amperes of electricity than others, which makes them to charge faster, but they need to ask the charger to give them more amps, and charger should be capable of understanding that request and providing more electricity.

if there is no request from phone for more amps, all charges provide same low amps that were standard for older phones.

If you want the phone to charge faster, use the charger that came with it, or charger from another recent phone.

Most chargers are either 1A or 2.1A. Higher the amperage, the more electricity can flow, at the same speed. This will allow the phone to charge quicker. The phone itself understands how charged it is, and cuts it off from the power when it is complete. The charger/wall wart itself is just converting from the 120/240v in your wall down to the 5v needed to charge your device.

Think of it like a garden hose… more voltage is like turning the spigot on higher, amperage is like getting a fatter hose.

actually they either naturally limit electrical current by design or have control circuitry to slow the influx of electricity to protect it’s self(usually from over heating)

all circuits(anything that does anything with or to electricity) operate on ‘available current’ meaning any power on a circuit will be used as quickly/heavily as possible. so circuits are designed to control that flow first.

some verbiage may include pulling current or pulling juice or ‘how much power is it pulling’ but it is in accurate. it’s simply letting it out.

Most phones have a USB connector. There’s a written standard for how that works for charging. The phone detects a voltage and says “hey, im connected to something. Wonder if it’s a good source of energy, or maybe it wants to give me data or something!” Then the phone and the charger send short bursts of voltage back and forth to each other, signalling like

&#x200B;

“Hey can I pull energy from you?”

“YES”

“Can I have this much?”

“YES”

“Can I have *this* much?”

“YES”

“Can I have ***THIS*** much??”

“**NO**”.

“OK!”

It’s more like the wall is pushing the electricity out, and your phone’s charger has circuitry that controls exactly how much electricity gets pushed into your phone. Simple chargers let electricity out at either 0.5 or 1 amps (an amp is a coulomb per second and a coulomb is just a number of electrons, so you can just think of it as some number of electrons per second) while some chargers have special circuitry that talks to the phone through the cable and decides how to maximize the amount of electricity it passes through the phone without damaging it.