Charging phone with USB in car?

[Lar]

I'm reading that my car usb outlet has just 0.5 amps and that it may not be enough to charge my phone and use the GPS. So I'm looking at using the 12 volt outlet with a usb converter but they all seem to say 4 amp which is double what my home wall charger is.  Is a 4 amp usb terminal too much for my phone since it already gets hot on the  2 amp charger? 

Thanks

[krazykiwi]

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@Psygineer wrote:

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@krazykiwi wrote:

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Eh? While technically more accurate to call it an adapter, many products call the power adapters for cellphones chargers. Even my Duracell I mentioned calls it a charger right on its package. Oddly enough my Laptop power supply brick says "90W Power Adapter" on it. I used the term charger rather than adapter simply because it is often used interchangeably (even if inaccurately) and I more commonly hear it called a charger.

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I understand, I interchange the 2 words often too. The only reason I took the time to explain the difference is because a lot of inexperienced people believe an adapter for a phone or tablet are like the charger/adapter for most laptops where they have to be an exact match when it comes to volts x amps = Watts. With phones that have the charger built in, they will regulate how much amps is needed and adjust accordingly so an exact match is not critical.

[Psygineer]

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@krazykiwi wrote:

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@Psygineer wrote:

Are you sure the charger actually outputs 4A to a single port though? If it is a dual port unit, it likely means it is 2A per USB port. I have a Duracell brand charger that claims to be 4.2A but in reality it is 2x2.1A. 

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Most dual port rated "Chargers" are like @Psygineer said, shared. However most also do not divide when there is only one device connected. So in your example 2 devices would receive a max of 2.1 amps and one device would receive a max of 4.2 amps. Note that I said most!

Also I quoted "Chargers" because unlike a laptop that has a external charger, phones have the charger built in and the unit that plugs into your wall or 12 volt port is merely a transformer (adapter) supplying the correct voltage. The phone which has the charger determines how much amperage it will draw.

There are a few different schools of thought when it comes to this but if you consider a 40 watt light bulb draws about .36 amps yet it is connected to a 15 amp circuit, why doesn't that bulb burn out? The amperage rating of an adapter is merely the max in can put out.

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Eh? While technically more accurate to call it an adapter, many products call the power adapters for cellphones chargers. Even my Duracell I mentioned calls it a charger right on its package. Oddly enough my Laptop power supply brick says "90W Power Adapter" on it. I used the term charger rather than adapter simply because it is often used interchangeably (even if inaccurately) and I more commonly hear it called a charger.

[krazykiwi]

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@Lar wrote:

It seems looking deeper into the 12v usb items that as suggested if only one thing is plugged into a two usb plug then you get the full 4.8 amps. If two things are plugged in then they split the amps.

Moving on, I have a small 80 watt inverter for the 12v car socket and could plug one of my three house chargers into that.  I have 1 amp, 1.5 amp and a 2 amps that came with the phone. My daughter has suggested I get a powerbank and  be done with it.  Thoughts

Thank you everyone for you ideas on this.

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A powerbank can be good, careful though there are a lot of crappy ones out there. If you are just want it for while you are in the car get the 12 volt adapter that fits your cigarette lighter socket. This does away with the need for the  inverter and house adapters and you can get a decent one for $10.

[Lar]

It seems looking deeper into the 12v usb items that as suggested if only one thing is plugged into a two usb plug then you get the full 4.8 amps. If two things are plugged in then they split the amps.

Moving on, I have a small 80 watt inverter for the 12v car socket and could plug one of my three house chargers into that.  I have 1 amp, 1.5 amp and a 2 amps that came with the phone. My daughter has suggested I get a powerbank and  be done with it.  Thoughts

Thank you everyone for you ideas on this.

[krazykiwi · Accepted solution]

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@Psygineer wrote:

Are you sure the charger actually outputs 4A to a single port though? If it is a dual port unit, it likely means it is 2A per USB port. I have a Duracell brand charger that claims to be 4.2A but in reality it is 2x2.1A. 

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Most dual port rated "Chargers" are like @Psygineer said, shared. However most also do not divide when there is only one device connected. So in your example 2 devices would receive a max of 2.1 amps and one device would receive a max of 4.2 amps. Note that I said most!

Also I quoted "Chargers" because unlike a laptop that has a external charger, phones have the charger built in and the unit that plugs into your wall or 12 volt port is merely a transformer (adapter) supplying the correct voltage. The phone which has the charger determines how much amperage it will draw.

There are a few different schools of thought when it comes to this but if you consider a 40 watt light bulb draws about .36 amps yet it is connected to a 15 amp circuit, why doesn't that bulb burn out? The amperage rating of an adapter is merely the max in can put out.

[Psygineer]

Are you sure the charger actually outputs 4A to a single port though? If it is a dual port unit, it likely means it is 2A per USB port. I have a Duracell brand charger that claims to be 4.2A but in reality it is 2x2.1A. 

[popping]

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@Lar wrote:

I'm reading that my car usb outlet has just 0.5 amps and that it may not be enough to charge my phone and use the GPS. So I'm looking at using the 12 volt outlet with a usb converter but they all seem to say 4 amp which is double what my home wall charger is.  Is a 4 amp usb terminal too much for my phone since it already gets hot on the  2 amp charger? 

Thanks

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The charger can supply 4A.  But your phone only draws(sucks) 2A from your charge.  The 4A charger will continue to supply more than 2A is your phone is drawing more than 2A.

You need to test it how much your phone draws to be on the safe side.

Heat is bad for battery and will shorten the battery life.  If your phone is already getting too hot while charged with a 2A charger, I will not use the 4A charger.