Question About USB Wall Adapter

[Continuity]

I would use the lower amp supply to charge onboard battery types of mods....
better to slow charge a system than overcharge one with a hi amp supply...
some circuits are designed to only take 1 A or less charge and when confronted with a higher ( stronger) current it may allow that current to flow but the internal circuitry wont be able to handle the higher current flow and overheat the system being charged...

Again - not true.

As others have posted - a device will take what current it needs from a power supply, the power supply will not 'push' more Amps into the device being charged.

And your advice is actually not just wrong, but potentially dangerous - if you power a device that wants 1A to charge with a 0.5A supply, it won't 'slow charge' and be 'better for the battery' it will just overtax the underrated power supply, making it run hot, or even fail.

On the other hand, if you're charging a device that requires 1A from a power supply capable of providing 3A, then the device will receive its 1A and the supply still has a comfortable headroom of 2A so it's well within its comfort zone.

 

[Eskie]

And your advice is actually not just wrong, but potentially dangerous - if you power a device that wants 1A to charge with a 0.5A supply, it won't 'slow charge' and be 'better for the battery' it will just overtax the underrated power supply, making it run hot, or even fail.

I would add one clarification. Should you choose to charge a device from the USB port on your computer, that port will only supply 0.5A. If your device is specked to charge at 1A or 2A, but meets USB standards, it will not result in failure of your USB port/computer/laptop. It will charge slowly, painfully so for something designed to draw 2A.

A cheap 0.5A USB plug may very well fail. A cheap USB plug "rated" at 2A or 3A may very well fail. Spend the extra dollar or two on a decent model. There was a link earlier to an Xstar plug that was well priced, it will be fine.

 

[ShamrockPat]

3. Which is best, 1A or 2.1A for charging? All USB 'draw' their current from the charger. It will only draw what it wants, so yes, plug into the 2.1A port for faster charging (if it supports it), or the 1A if you want to limit it to that maximum.

 

[Rickajho]

Yep in the case of lithium battery chargers anyway.
If the device needs more amps/current than the adapter can supply then one gets into heated circuits, voltage drop, etc issues.

But with smart USB devices that no longer applies. My Android phone "wants" a 2100 mA output power supply. The key word here being smart. If I plug that phone into a supply that can only deliver 500 mA current the phones charging circuitry will dumb all the way down to only drawing a lowly 350 mA current from that 500 mA supply. It will (eventually) charge the battery with no damage to the power supply in the process.

For that matter every recent Xtar battery charger I have tested that uses a USB power supply does the same thing - from a 4 bay VC4 to an MP2 to a single cell XP1. They all read the current draw from the power supply in context of the power supply output voltage and adjust their charge current levels accordingly. (If you think USB is always a fixed 5 volts no matter what - think again.) This behavior can be confirmed by getting an inexpensive USB voltage/current in-line meter yourself, and in the independent tests done on specific chargers. Xtar makes a point of this in their own product descriptions as well.

This is by design on purpose. We are at the point of having truly idiot Darwin proof smart devices we can plug into any USB power supply and not have to ponder possible damage from mismatched current demands and power supply capabilities as we did even two years ago. At this point more output current available is better and won't hurt anything. Low output current will only slow things down but won't damage the power supply either.

 

[Robert Cromwell]

But with smart USB devices that no longer applies. My Android phone "wants" a 2100 mA output power supply. The key word here being smart. If I plug that phone into a supply that can only deliver 500 mA current the phones charging circuitry will dumb all the way down to only drawing a lowly 350 mA current from that 500 mA supply. It will (eventually) charge the battery with no damage to the power supply in the process.

For that matter every recent Xtar battery charger I have tested that uses a USB power supply does the same thing - from a 4 bay VC4 to an MP2 to a single cell XP1. They all read the current draw from the power supply in context of the power supply output voltage and adjust their charge current levels accordingly. (If you think USB is always a fixed 5 volts no matter what - think again.) This behavior can be confirmed by getting an inexpensive USB voltage/current in-line meter yourself, and in the independent tests done on specific chargers. Xtar makes a point of this in their own product descriptions as well.

This is by design on purpose. We are at the point of having truly idiot Darwin proof smart devices we can plug into any USB power supply and not have to ponder possible damage from mismatched current demands and power supply capabilities as we did even two years ago. At this point more output current available is better and won't hurt anything. Low output current will only slow things down but won't damage the power supply either.

True, some devices have a smart battery charge circuit.

 

[Canadian_Vaper]

I would add one clarification. Should you choose to charge a device from the USB port on your computer, that port will only supply 0.5A. If your device is specked to charge at 1A or 2A, but meets USB standards, it will not result in failure of your USB port/computer/laptop. It will charge slowly, painfully so for something designed to draw 2A.

Some newer computers have quick charge, my USB ports are 2.1A but like you said most are .5a

 

[daviedog]

The adapter that plugs into the wall (mains) is a power supply not a charger, the charger is in the device (mod).

Step down transformer..

 

[Robert Cromwell]

Step down transformer..

Most 'Wall Warts' are Switching type power supplies and contain no transformer.

 

[Eskie]

Some newer computers have quick charge, my USB ports are 2.1A but like you said most are .5a

Really? That's a nice touch. The only time I've been able to draw anything higher was with from the USB 3 and matching device. Given how much stuff needs to be charged these days, that can be convenient.

For that matter I carry a 10,000 maH charging battery with me which has multiple taps and can charge at up to 3.1 A. Great when traveling and there are just no outlets to be found.

 

[djsvapour]

I use a quality wall adapter for everything now. Sure, it's made in China but imported to a local company that then sells across Europe. About 12 GBP/ pounds

 

[Robert Cromwell]

Really? That's a nice touch. The only time I've been able to draw anything higher was with from the USB 3 and matching device. Given how much stuff needs to be charged these days, that can be convenient.

For that matter I carry a 10,000 maH charging battery with me which has multiple taps and can charge at up to 3.1 A. Great when traveling and there are just no outlets to be found.

I think USB 3.0 is 2 amps but the older versions are 1? amp? I know they are less current.

 

[Eskie]

I think USB 3.0 is 2 amps but the older versions are 1? amp? I know they are less current.

The "old" USB 2 standard was 0.5 A. Not sure if they ever officially upped it on computers, although @Asylumsix stated they have 2.1A output from their USB.

 

[Eskie]

I use a quality wall adapter for everything now. Sure, it's made in China but imported to a local company that then sells across Europe. About 12 GBP/ pounds

I would say 99.9% are made in China these days. Which is fine if bought through a manufacturer or reseller who specify and assure it meets specs before retail sale. It's the no name/unknown name ones where corners may be cut. Same thing with batteries. All the Samsung/LG/Sony batteries we buy are from China, but those wrapped and sold by them are of known quality. Rewraps of generic batteries also made in China, never mind counterfeits, are best to avoid as well.

 

[daviedog]

Most 'Wall Warts' are Switching type power supplies and contain no transformer.

Most 'Wall Warts' are Switching type power supplies and contain no transformer.

SMPS,, mains voltage is rectified to a high direct voltage driving a switching circuit containing a Transformer operating at high frequency to Output current at a desired voltage..

 

[AzPlumber]

Step down transformer..

You can use a transformer to decrease AC voltage but need a voltage converter to go from AC to DC.

 

[AzPlumber]

Step down transformer..

I assume ^this^ was to correct me calling it a power supply but your next post below explains that a transformer is part of a SMPS (Switch-Mode POWER SUPPLY.)

SMPS,, mains voltage is rectified to a high direct voltage driving a switching circuit containing a Transformer operating at high frequency to Output current at a desired voltage..

 

[NealBJr]

Again - not true.

As others have posted - a device will take what current it needs from a power supply, the power supply will not 'push' more Amps into the device being charged.

And your advice is actually not just wrong, but potentially dangerous - if you power a device that wants 1A to charge with a 0.5A supply, it won't 'slow charge' and be 'better for the battery' it will just overtax the underrated power supply, making it run hot, or even fail.

On the other hand, if you're charging a device that requires 1A from a power supply capable of providing 3A, then the device will receive its 1A and the supply still has a comfortable headroom of 2A so it's well within its comfort zone.

The correct answer, is find out the manufacturers recommended power supply rating, and use that. Underpowering is ok, and overpowering can be dangerous. You're assuming the charging circuit is well designed to take whatever charge it needs..which is not necessarily true. There have been a large number of EGO batteries that supplied too many amps to the battery, and it caused those batteries to explode... same thing goes with ANY lithium ion powered device.

Most people don't realize, that even though there's a max discharge rating for the battery, there is also a max CHARGE rating for a battery. Many are in the 2-3 amp range. Supplying more can damage the battery and potentially make it explode. In the EGO reference above, most people's batteries exploded when they plugged it into their cellphone charger... which probably supplied 2.1 amps. The electronics in an EGO battery are VERY small, and the battery is low quality, so the chances of those exploding are much higher than the larger battery mods.

Keep in mind, the larger chargers usually charge the batteries at .5 or 1 amp, and are much safer than onboard chargers.... why even attempt to go higher?

 

[AzPlumber]

The correct answer, is find out the manufacturers recommended power supply rating, and use that. Underpowering is ok, and overpowering can be dangerous. You're assuming the charging circuit is well designed to take whatever charge it needs..which is not necessarily true. There have been a large number of EGO batteries that supplied too many amps to the battery, and it caused those batteries to explode... same thing goes with ANY lithium ion powered device.

Most people don't realize, that even though there's a max discharge rating for the battery, there is also a max CHARGE rating for a battery. Many are in the 2-3 amp range. Supplying more can damage the battery and potentially make it explode. In the EGO reference above, most people's batteries exploded when they plugged it into their cellphone charger... which probably supplied 2.1 amps. The electronics in an EGO battery are VERY small, and the battery is low quality, so the chances of those exploding are much higher than the larger battery mods.

Keep in mind, the larger chargers usually charge the batteries at .5 or 1 amp, and are much safer than onboard chargers.... why even attempt to go higher?

NO, the correct answer is the on-board charger determines the charge rate NOT the power supply (wall wart).

 

[NealBJr]

NO, the correct answer is the on-board charger determines the charge rate NOT the power supply (wall wart).

....yes...you're right, the onboard-charger determines the charge rate, not the power supply... That's assuming the onboard charger is intelligent enough to convert and how it converts. With the small ecig electronics on board, I prefer to use a dedicated charger, or if I have to use the onboard charger, use the manufacturer's recommended rating. Supplying a higher amp current is another variable that could otherwise be avoided by simply buying the right charger.

 

[AzPlumber]

....yes...you're right, the onboard-charger determines the charge rate, not the power supply... That's assuming the onboard charger is intelligent enough to convert and how it converts. With the small ecig electronics on board, I prefer to use a dedicated charger, or if I have to use the onboard charger, use the manufacturer's recommended rating. Supplying a higher amp current is another variable that could otherwise be avoided by simply buying the right charger.

The amperage rating on a power supply is no different than the amperage rating on a battery. Use a battery that can't safely provide the amperage required and bad things happen, use a power supply that can't safely provide the amperage required and bad things happen.