AC Chargers - Watts? Volts? mAmps?

odamizu · 05-14-2016, 01:24 PM

Is a 5W USB charger the same as a 5V charger?

I have 2 Sony chargers:

#1: 5V 1,000 mA
#2: 5.2V 1,500 mA

And then there are the Kindle official chargers:

#1: 5W 1A
#2: 9W 1.8A

I am confused. How do watts and volts and mA compare?

Thanks!

Yolina · 05-14-2016, 01:33 PM

Watts = Amps x Volts

GERGE · 05-14-2016, 02:43 PM

Higher amperage means shorter charging as long as the battery supports it. Otherwise means damage, but usually not with modern devices.

theducks · 05-14-2016, 03:18 PM

All those listed are constant voltage chargers/battery eliminators (fixed voltage listed)
5W is NOT always 5V << It must say 5V (a 5W, 5V charger is about 1A)

In addition, the 5.1 volt one is within the 5% tolerance (5V) common to computer chips in time of old (TTL, LSTTL). Since there is no such thing as a Negative Voltage DROP, 5.1V makes up for wire and connector losses, still with a safety margin

Current is how fast the charger (If allowed) can charge. If too low, the device may elect a 'slow mode' or just not Charge

Watts is just another way of specifying capacity I*E (Amps * Volts)
so, there is no problem using any of thos with a proper functioning device.*

Some devices (like Audio) Specify Peak Power. This is short bursts with a recovery time (cooling and power supply) in between. The number looks great in advertising

, but you will be dissatisfied (and possibly damage speakers) if you need more than the Continuous Power rating.

BTW do not confuse INPUT Power (usually in VA). All devices are inefficient. You put more W in than you get out the lead (the rest is heat)

* don't get crazy over-sizing. If your device fails, the charger also limits to around that value (native over current limiting).

dwig · 05-14-2016, 03:19 PM

Quote:

Originally Posted by odamizu

Is a 5W USB charger the same as a 5V charger?

I have 2 Sony chargers:

#1: 5V 1,000 mA
#2: 5.2V 1,500 mA

And then there are the Kindle official chargers:

#1: 5W 1A
#2: 9W 1.8A

I am confused. How do watts and volts and mA compare?

Thanks!

As Yolinda correctly stated, with DC, like we are dealing with here, it is a simple formula, Watts = Volts x Amps. Also, 1 A = 1000 mA (the "m" means 1/1000th).

With the Kindle chargers you can tell that they operate at 5v since 5W / 1A = 5V and 9W / 1.8A = 5V. The Sony #1 would also be 5W and #2 would be roughly 7.6W.

Bob B · 05-14-2016, 03:23 PM

Quote:

Originally Posted by odamizu

Is a 5W USB charger the same as a 5V charger?

I have 2 Sony chargers:

#1: 5V 1,000 mA
#2: 5.2V 1,500 mA

And then there are the Kindle official chargers:

#1: 5W 1A
#2: 9W 1.8A

I am confused. How do watts and volts and mA compare?

Thanks!

You are asking about Ohm's Law. Goggle it for tons of explanations and formulas. It is one of the most basic principles of electricity.

The Sony chargers have different voltages. This may be a problem, but the difference is not much.

As for the Kindle chargers you mentioned, if they are the same voltage, either may be used. #2 just has a higher current capacity, but will not harm anything. the device you are powering will just draw what it needs.

crich70 · 05-14-2016, 06:19 PM

And it's not the voltage that presents the real danger with electricity but the Amperage. I could touch something with a 50,000 voltage but if there isn't any amperage I won't be harmed but only half an amp is enough amperage to kill someone. That's the reason for the Danger High Voltage signs. It's because of the current which is measured in Amps. We use AC (Alternating Current) rather than DC (Direct Current) because AC can be pushed farther through wires than DC can. With a DC power Plant you would need a power plant every few blocks rather than one or two per average town. Many devices however need DC to run properly so the current is stepped down when it comes into a building and converted to DC at the point it enters the machine via it's power supply. And electronic devices are sensitive to voltage and amps. Too much and you end up frying chips.

odamizu · 05-14-2016, 08:23 PM

Oy. I only partially understood what everyone said — though I am very grateful for all the attempts to help me understand.

If I'm understanding correctly, Sony #1 and Kindle #1 are the same, and most USB chargers can be used with most devices, which will only draw the amount they need, but it's not 100% sure so there's always a risk (generally small) of frying your device if you don't use the "official" charger that goes with it? Does that pretty much sum it up?

So the safest thing is to buy the "official" charger or use one with the exact equivalent voltage and amperage?

Cinisajoy · 05-14-2016, 08:54 PM

Quote:

Originally Posted by odamizu

Oy. I only partially understood what everyone said — though I am very grateful for all the attempts to help me understand.

If I'm understanding correctly, Sony #1 and Kindle #1 are the same, and most USB chargers can be used with most devices, which will only draw the amount they need, but it's not 100% sure so there's always a risk (generally small) of frying your device if you don't use the "official" charger that goes with it? Does that pretty much sum it up?

So the safest thing is to buy the "official" charger or use one with the exact equivalent voltage and amperage?

Yes, that is safest.
Most batteries now have safeguards to keep from overcharging.

Now if you use an unauthorized battery in a Samsung phone and charge it under your pillow, you could start a fire. (Read on the internet)
Or if you duct tape your entire phone it will eventually overheat. (My daughter did this one).

I use the same chargers for all my devices.
Oh wait the Kobo and Garmin require a mini usb as opposed to the micro usb.

Other fun stuff 1 Amp is approximately 110 Watts.
Therefore if you have a 20 Amp breaker do not try to run your 1500 watt toaster oven and your 1100 watt microwave at the same time. You will trip the breaker.
I have labeled all my small appliances A, B or C.
A is 1000 watts or higher, B is 500 to 999 watts, C is less than 500 watts.
That way I don't trip a breaker.

odamizu · 05-14-2016, 09:52 PM

Now my head is spinning

Bricorn · 05-15-2016, 02:49 PM

Basically, if you don't know what you're doing, stick to the charger that comes with the device.

Electricity is so pervasive in our lives that we tend not to notice it; we press a button, flick a switch, and something in our world changes. If the change was what we expected, we don't consciously notice it - when was the last time you walked into a room, flicked the light switch, and thought about all the infrastructure in place to get the power to you, or all the hardware involved; generators, wires, transformers, switches, even the bulb itself.

What we forget is that electricity isn't a willing servant, it's a chained demon. Handle it wrongly and you can blow electronics in a fraction of a second, cause fires quickly, and injure or kill directly in a very short time.

Again, if you don't know what you're doing, don't play with it, the possible consequences range from none to minor to disastrous.

dwig · 05-15-2016, 03:06 PM

Quote:

Originally Posted by odamizu

Now my head is spinning

Playing around with AC will make your head spin.

Back to chargers, there is another issue to consider. With most tablets and phones the "data" lines (USB2 uses 2 wires for power and 2 wires + the power ground wire for data) are often used to signal the device that a charger is present. There is a USB standard for this, but many devices use their own proprietary system. This can result in a charger with perfectly appropriate voltage and current specs to fail to charge a particular device. Again, the easy, simple solution is to stick with the manufacturer's original charger.

At my house, my wife and I have a wide variety of chargers. Our phones, Bluetooth speakers, Bluetooth headsets, ... all charge fine on all chargers. My phone complains about some of the chargers, but works fine anyway. The one outlier is my Dell Venue 8 pro. It won't charge from one of our universal AC power strips with USB outlets (works with the other one from a different brand) and only works with one of the two outlets on a GE brand dual charger. The Dell doesn't seem to "get the message" from the two chargers that fail.

Bob B · 05-15-2016, 03:33 PM

Quote:

Originally Posted by odamizu

If I'm understanding correctly, Sony #1 and Kindle #1 are the same,...

Can't say because you didn't state the voltage of the Kindle adapters.

Cinisajoy · 05-15-2016, 05:20 PM

Quote:

Originally Posted by dwig

Playing around with AC will make your head spin.

Back to chargers, there is another issue to consider. With most tablets and phones the "data" lines (USB2 uses 2 wires for power and 2 wires + the power ground wire for data) are often used to signal the device that a charger is present. There is a USB standard for this, but many devices use their own proprietary system. This can result in a charger with perfectly appropriate voltage and current specs to fail to charge a particular device. Again, the easy, simple solution is to stick with the manufacturer's original charger.

At my house, my wife and I have a wide variety of chargers. Our phones, Bluetooth speakers, Bluetooth headsets, ... all charge fine on all chargers. My phone complains about some of the chargers, but works fine anyway. The one outlier is my Dell Venue 8 pro. It won't charge from one of our universal AC power strips with USB outlets (works with the other one from a different brand) and only works with one of the two outlets on a GE brand dual charger. The Dell doesn't seem to "get the message" from the two chargers that fail.

I guess I should clarify all my adapters work on all my devices, but not all my USB cables work on all devices.

theducks · 05-15-2016, 06:48 PM

If it uses a standard USB jack (the flat one) like on your computer, it is 5 Volts +/- 5%

WHICH BRINGS UP
A Real USB port has a limit of 500ma (0.5A) built into the drive chip, which is why you need a external 'charger' for those power hungry Tablets and phones

The port will trip the over current circuit and will need to be reset if the device does not shift to SLOW/no charge mode

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05-14-2016, 01:24 PM	#1
odamizu just an egg Posts: 1,586 Karma: 4300000 Join Date: Mar 2015 Device: Kindle, iOS	AC Chargers - Watts? Volts? mAmps? Is a 5W USB charger the same as a 5V charger? I have 2 Sony chargers: #1: 5V 1,000 mA #2: 5.2V 1,500 mA And then there are the Kindle official chargers: #1: 5W 1A #2: 9W 1.8A I am confused. How do watts and volts and mA compare? Thanks!

05-14-2016, 01:33 PM	#2
Yolina Wizard Posts: 1,179 Karma: 11573197 Join Date: Feb 2011 Location: London, UK Device: Voyage	Watts = Amps x Volts

05-14-2016, 02:43 PM	#3
GERGE Guru Posts: 732 Karma: 5797160 Join Date: Jun 2010 Location: Istanbul Device: Kobo Libra	Higher amperage means shorter charging as long as the battery supports it. Otherwise means damage, but usually not with modern devices.

05-14-2016, 03:18 PM	#4
theducks Well trained by Cats Posts: 29,802 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	All those listed are constant voltage chargers/battery eliminators (fixed voltage listed) 5W is NOT always 5V << It must say 5V (a 5W, 5V charger is about 1A) In addition, the 5.1 volt one is within the 5% tolerance (5V) common to computer chips in time of old (TTL, LSTTL). Since there is no such thing as a Negative Voltage DROP, 5.1V makes up for wire and connector losses, still with a safety margin Current is how fast the charger (If allowed) can charge. If too low, the device may elect a 'slow mode' or just not Charge Watts is just another way of specifying capacity IE (Amps Volts) so, there is no problem using any of thos with a proper functioning device.* Some devices (like Audio) Specify Peak Power. This is short bursts with a recovery time (cooling and power supply) in between. The number looks great in advertising , but you will be dissatisfied (and possibly damage speakers) if you need more than the Continuous Power rating. BTW do not confuse INPUT Power (usually in VA). All devices are inefficient. You put more W in than you get out the lead (the rest is heat) * don't get crazy over-sizing. If your device fails, the charger also limits to around that value (native over current limiting).

05-14-2016, 06:19 PM	#7
crich70 Grand Sorcerer Posts: 11,305 Karma: 43993832 Join Date: Feb 2010 Location: Monroe Wisconsin Device: K3, Kindle Paperwhite, Calibre, and Mobipocket for Pc (netbook)	And it's not the voltage that presents the real danger with electricity but the Amperage. I could touch something with a 50,000 voltage but if there isn't any amperage I won't be harmed but only half an amp is enough amperage to kill someone. That's the reason for the Danger High Voltage signs. It's because of the current which is measured in Amps. We use AC (Alternating Current) rather than DC (Direct Current) because AC can be pushed farther through wires than DC can. With a DC power Plant you would need a power plant every few blocks rather than one or two per average town. Many devices however need DC to run properly so the current is stepped down when it comes into a building and converted to DC at the point it enters the machine via it's power supply. And electronic devices are sensitive to voltage and amps. Too much and you end up frying chips.

05-14-2016, 08:23 PM	#8
odamizu just an egg Posts: 1,586 Karma: 4300000 Join Date: Mar 2015 Device: Kindle, iOS	Oy. I only partially understood what everyone said — though I am very grateful for all the attempts to help me understand. If I'm understanding correctly, Sony #1 and Kindle #1 are the same, and most USB chargers can be used with most devices, which will only draw the amount they need, but it's not 100% sure so there's always a risk (generally small) of frying your device if you don't use the "official" charger that goes with it? Does that pretty much sum it up? So the safest thing is to buy the "official" charger or use one with the exact equivalent voltage and amperage?

05-14-2016, 09:52 PM	#10
odamizu just an egg Posts: 1,586 Karma: 4300000 Join Date: Mar 2015 Device: Kindle, iOS	Now my head is spinning

05-15-2016, 02:49 PM	#11
Bricorn Addict Posts: 289 Karma: 7788748 Join Date: Sep 2009 Location: Fun Town, Thailand Device: Kindle DXG	Basically, if you don't know what you're doing, stick to the charger that comes with the device. Electricity is so pervasive in our lives that we tend not to notice it; we press a button, flick a switch, and something in our world changes. If the change was what we expected, we don't consciously notice it - when was the last time you walked into a room, flicked the light switch, and thought about all the infrastructure in place to get the power to you, or all the hardware involved; generators, wires, transformers, switches, even the bulb itself. What we forget is that electricity isn't a willing servant, it's a chained demon. Handle it wrongly and you can blow electronics in a fraction of a second, cause fires quickly, and injure or kill directly in a very short time. Again, if you don't know what you're doing, don't play with it, the possible consequences range from none to minor to disastrous.

05-15-2016, 06:48 PM	#15
theducks Well trained by Cats Posts: 29,802 Karma: 54830978 Join Date: Aug 2009 Location: The Central Coast of California Device: Kobo Libra2,Kobo Aura2v1, K4NT(Fixed: New Bat.), Galaxy Tab A	If it uses a standard USB jack (the flat one) like on your computer, it is 5 Volts +/- 5% WHICH BRINGS UP A Real USB port has a limit of 500ma (0.5A) built into the drive chip, which is why you need a external 'charger' for those power hungry Tablets and phones The port will trip the over current circuit and will need to be reset if the device does not shift to SLOW/no charge mode

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