General Question

Bluefreedom's avatar

If you’re charging a cellular phone using a home outlet, wouldn’t the more powerful current charge a phone faster than using a vehicle’s power to charge the same cellular phone?

Asked by Bluefreedom (22944points) December 7th, 2010

I noticed yesterday that when I made a 30 minute drive home from work and charged my cellular phone (the battery was almost dead) using the vehicle charger, it was at a full charge on arriving home. When I’ve charged my phone at home, it usually takes anywhere from 60 to 90 minutes, on average, that I’ve seen.

My interest in this, mostly being curiousity and nothing else is, if you’re charging a phone using a home outlet, wouldn’t the more powerful current charge a phone faster than using a vehicle’s power? And, it the opposite is true, what causes the vehicle to be able to charge electronic items faster?

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11 Answers

john65pennington's avatar

Do you understand the difference between AC and DC?

Bluefreedom's avatar

I know what the initials stand for. One’s Alternating and the other is Direct current but as far as knowing the differences like an electrician would, for instance, no, I don’t know much about the processes of either of them.

RocketGuy's avatar

My guess is that the home charger (AC) is designed to gently charge the battery – so the battery will last many years, and home users charge overnight, so no need to hurry.

The car charger (DC) may be designed to charge up a battery before the end of an average trip, which may be 30 min. Actually, I have always believed that designers of cheap car chargers don’t care, and let the charger go as fast as their cheapest design will allow. No power regulation, no cares about battery longevity.

Rarebear's avatar

@RocketGuy Although you’d think they’d design it so the electronics in the phone would account for that.

IchtheosaurusRex's avatar

They’re probably not delivering the charging current at the same rates. Your DC adapter may contain nothing more than a resistor to limit the current, which would be sloppier than using PWM to regulate it. Considering how cheap cell chargers are, I’d be surprised if the wall charger has any current regulation, either. I suspect it’s built in to the phone. Your wally will contain a solid-state device that both rectifies and clips the house current to a value that won’t make your phone explode. If I think about it, I’ll cut open an old one to see what’s inside it.

RocketGuy's avatar

My home chargers cool down when the phone battery gets full. Prob. some semi-advanced technology there. My car charger is warm all the time.

LuckyGuy's avatar

As with all thing electronic, “Heat is what kills ‘em.” Batteries are no different. Their usable life is severely reduced if they are subjected to high temp.
Why would they heat up? If you put in too much current without the battery being able to dissipate the internal heat. Sure you can make a cell phone battery charge quicker. But you would only get 50 full charges out of it. The LiPo batteries most of us are carrying in our pants are only good for about 300 full charges when charged slowly. Good car and home chargers have current limiters built in so the batteries to not get too hot. That costs a little more but protects the battery. The cheap, Chinese knock-off chargers for $5 don’t. Your battery may charge really fast but you will need a $35 battery in about 6 months instead of a year.
It is far better to use the good home charger for the bulk of your charging needs and only use the car charger for emergency backup.

Bluefreedom's avatar

@Everyone. Thanks for the great answers!

jerv's avatar

@worriedguy Not really an issue if you have good chargers at both ends. Besides, you can’t use your dash-mounted smartphone as a GPS without a car charger.
I have a similar commute time, but my Droid X only recovers 20–30% if I leave it alone in it’s dock to just charge, and closer to 10% if I use the GPS and/or streaming audio. Somehow, I don’t see a risk with my Motorola charger. Now, the OP with their “blast charger” is going to run into problems, and probably soon.

@RocketGuy You need a better car charger too. Mine is often one of the coolest things on/in my dash, so something isn’t right with you!

RocketGuy's avatar

@jerv – Well, then I would have to spend real money for a car charger. I only use it a few times a year.

jerv's avatar

@RocketGuy Ah. I use mine daily, so it makes sense for me. If you use yours so rarely though…

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