Why does it take a long time to charge an iPhone or laptop from 0% to 100% instead of just a few minutes/seconds?

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Why does it take a long time to charge an iPhone or laptop from 0% to 100% instead of just a few minutes/seconds?

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Because all batteries have a safe charging rate. If you charge them faster than this they’ll tend to overheat and explode 🙂

Perhaps you’ve heard of the Samsung phones that caught fire when they were charging. Catching fire only required about 10% too much current. To charge an iPhone in seconds would take 100 times too much current. That isn’t safe in any way.

Charging a battery gives off heat. It also shortens the life of that battery. The faster you charge the battery the more heat it gives off and the faster it shortens it’s life.

So it’s a balancing act between a reasonable charge time of that battery and not cooking it and killing it prematurely.

One way to get around this is have something that can soak up the charge really fast without cooking it. A capacitor if you will. Then that capacitor feeds the power into the battery at a more reasonable rate.

That is the idea behind graphene lith-ion hybrid batteries.

As for the newer iPhone super fast charge I have no idea how the are doing it, but I suspect they are sacrificing long term batter life for charging speed.

My favorite way I’ve heard this explained is – compare a) charging your battery to b) filling up a cup with water from a faucet. You can only fill the cup up so quickly, without spilling water out of the cup into the sink. The difference is, with a battery, if you fill it too quickly and it “spills”, then your battery explodes. So, charging rates for any battery will always be well below that “possible spill” rate.

If you use the supplied charger it should charge fairly quickly. My Samsung phone came with a fast charger. It will charge my phone from almost dead to 100% in about 20 minutes and my Samsung Galaxy watch much quicker. Same with my Ipad Pro.