Nope! You have that reversed. Voltage is the speed in which it flows. Amps is the amount of electrons moving through the hose. Basic electronics.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
is charging on new ipad this slow ?
- Thread starter ansabakhan
- Start date
- Sort by reaction score
I stand corrected, but still think that 2.1 amps is a lot for a small flexable cord!
It is which is why I think a lot of people are running into issues. While the iPhone cord looks pretty much the same as the iPad cord, they could be designed differently. It's quite possible that the iPhone cord cannot carry the full 2 amps causing a slower charging rate for the iPad.
Excellent post but for 1 minor point. USB standards is 5v @ 500mah, the iPad charger is 2100mah so it doesn't meet the USB standards to start. The reason you can't overcharge it is because of the chipset which controls the charge rate.
Here is the test I ran. All tests were after fully discharging the NEW iPad down to ZERO where it shut itseflf down (all times are rounded +- 10%):
Apple OEM iPad 2 cable 6.5 hours on NEW iPad
Apple OEM iPad 3 cable 6.5 hours on NEW ipad
Khomo 6 foot cable (standard thin-ness cable): 4 hours on iPad 2
Khome 6 foot cable (standard thin-ness cable)15+ hours! on NEW iPad
Link to cable: http://www.amazon.com/gp/product/B005IR2J2M/ref=oh_o03_s00_i00_details
Apple OEM iPad cable with 24 gage 3' USB extension (heavy extension cable) on NEW iPad: 6.3 hrs
Monoprice VERY THICK 6' Apple sync cable: 5.75 hrs on NEW iPad.
Link to cable: http://www.monoprice.com/products/p...d=1083101&p_id=8738&seq=1&format=1#largeimage
Problem with the Monoprice cable is that it is so thick it doesn't flex at the point near the iPad connector and will likely (IMO) eventually damage the jack on the iPad.
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
You've got that one wrong. Pressure is comparable to voltage, amperage comparable to flow. Point your garden-hose upwards for a reminder. Higher pressure (voltage) will carry water higher.
Let's assume the wire is 24 AWG (I'm using American standards as a courtesy to you Americans
.) 24 AWG can carry 3.5A without getting hot. 7A will give you noticeable warming of the wire, and at 10A it will get hot.. (200ºF)A USB-connector is a bigger stumbling-block, with a designed maximum current of 1.8A. (according to the datasheets I have..). 2A is stretching it. To the max.
----------
Kudo's for mentioning batteryuniversity.com.
----------
Care to share at what speed electrons move?
Weird.
Mine went flat this afternoon. Plugged it into the official dock to charge at about 7pm. 6 hours later and it's at 45%
In standby or were you actively using it?
This is completely incorrect. The new iPad ships with the exact same cable and AC adapter as the iPad 2. Therefore using the "new" cable will not result in a faster charge, especially since the circuitry that manages the charging process is contained in the iPad itself, not in the cable or AC plug.
Wow, wow, wow. So many myths.
The iPad maximum current draw is 2.1 amp at approx 5 volts (5.1 on the charger because there will be some voltage drop on that tiny little cable. I don't know how think the wire is but I have an old cord that's fraying and can see in, insulation thickness and the similarity at tiny sizes affects it, but I don't think it's even 18AWG. It looks honestly similar to 24AWG like in CAT5. Many USB cables ARE 24AWG for power and 28 for data, and the standard allows just 28AWG - remember, 0.5a is the USB spec. It could be 20 or 22? Anyone know for sure? I can't find an exact answer clearly in a quick Google search.
Using this table - http://www.powerstream.com/Wire_Size.htm , the maximum loads for power transmission are 18AWG - 2.3a; 20AWG - 1.5a, 22AWG - 0.92a, 24AWG - 0.577a. Standards for chassis wiring are higher - 3.5a for 24AWG, since more resistance is acceptable (with corresponding voltage drop and head dissipation). Shorter runs have less voltage drops than longer runs.
Clearly, Apple (and other tablet makers) are literally pushing the edge of current draw over USB. Also, there aren't the standards for drawing 2amps that there are for phone chargers and normal USB ports.
Phone chargers have the data pins shorted with some resistance. The phones (and even the iPad!) will detect this is a 1 amp power source (technically they're not chargers the actual charger is in the device with Li-Ion) and not draw over 1 amp. The iPad will negotiate for 2.1amps with Apple's chargers and newer Macs. All devices designed to spec NEVER draw over 0.5a (standard USB spec) if they are uncertain of current availability. This is so your iPad doesn't burn up your PC's motherboard
Given the physical limits of this, the iPad charger is pretty much at the limits of power that can be done over standard USB - and pushing them. USB extension cables could EASILY result in too much voltage drop.
Firewire was FAR superior for this, since it's an unregulated, but nominally 25 volt connection (though many implementations were much lower and straight off the 12V rail; and Apple's chargers were 12V; Firewire devices had to be able to handle and use if they needed bus power, anywhere from 9 to 40 volts!). Much lower current involved. Much more complex electronic design. But if Apple HADN'T abandoned FireWire, they'd be reaping the benefits today by being able to offer much higher voltage wall chargers supplying much more power to the iPad 3 to charge.
So yeah, basically, quit complaining, even Apple has to live within the laws of physics. Either, make the battery life shorter, make the device use less power, live with the long charge times, or use a totally proprietary charger connection (or back to FireWire lol).
As for charging. Nothing kills a li-ion battery quicker than letting it totally die Other than that, don't worry
The iPad maximum current draw is 2.1 amp at approx 5 volts (5.1 on the charger because there will be some voltage drop on that tiny little cable. I don't know how think the wire is but I have an old cord that's fraying and can see in, insulation thickness and the similarity at tiny sizes affects it, but I don't think it's even 18AWG. It looks honestly similar to 24AWG like in CAT5. Many USB cables ARE 24AWG for power and 28 for data, and the standard allows just 28AWG - remember, 0.5a is the USB spec. It could be 20 or 22? Anyone know for sure? I can't find an exact answer clearly in a quick Google search.
Using this table - http://www.powerstream.com/Wire_Size.htm , the maximum loads for power transmission are 18AWG - 2.3a; 20AWG - 1.5a, 22AWG - 0.92a, 24AWG - 0.577a. Standards for chassis wiring are higher - 3.5a for 24AWG, since more resistance is acceptable (with corresponding voltage drop and head dissipation). Shorter runs have less voltage drops than longer runs.
Clearly, Apple (and other tablet makers) are literally pushing the edge of current draw over USB. Also, there aren't the standards for drawing 2amps that there are for phone chargers and normal USB ports.
Phone chargers have the data pins shorted with some resistance. The phones (and even the iPad!) will detect this is a 1 amp power source (technically they're not chargers the actual charger is in the device with Li-Ion) and not draw over 1 amp. The iPad will negotiate for 2.1amps with Apple's chargers and newer Macs. All devices designed to spec NEVER draw over 0.5a (standard USB spec) if they are uncertain of current availability. This is so your iPad doesn't burn up your PC's motherboard
Given the physical limits of this, the iPad charger is pretty much at the limits of power that can be done over standard USB - and pushing them. USB extension cables could EASILY result in too much voltage drop.
Firewire was FAR superior for this, since it's an unregulated, but nominally 25 volt connection (though many implementations were much lower and straight off the 12V rail; and Apple's chargers were 12V; Firewire devices had to be able to handle and use if they needed bus power, anywhere from 9 to 40 volts!). Much lower current involved. Much more complex electronic design. But if Apple HADN'T abandoned FireWire, they'd be reaping the benefits today by being able to offer much higher voltage wall chargers supplying much more power to the iPad 3 to charge.
So yeah, basically, quit complaining, even Apple has to live within the laws of physics. Either, make the battery life shorter, make the device use less power, live with the long charge times, or use a totally proprietary charger connection (or back to FireWire lol).
As for charging. Nothing kills a li-ion battery quicker than letting it totally die
Other than that, don't worry Wow, wow, wow. So many myths.
The iPad maximum current draw is 2.1 amp at approx 5 volts (5.1 on the charger because there will be some voltage drop on that tiny little cable. I don't know how think the wire is but I have an old cord that's fraying and can see in, insulation thickness and the similarity at tiny sizes affects it, but I don't think it's even 18AWG. It looks honestly similar to 24AWG like in CAT5. Many USB cables ARE 24AWG for power and 28 for data, and the standard allows just 28AWG - remember, 0.5a is the USB spec. It could be 20 or 22? Anyone know for sure? I can't find an exact answer clearly in a quick Google search.
Using this table - http://www.powerstream.com/Wire_Size.htm , the maximum loads for power transmission are 18AWG - 2.3a; 20AWG - 1.5a, 22AWG - 0.92a, 24AWG - 0.577a. Standards for chassis wiring are higher - 3.5a for 24AWG, since more resistance is acceptable (with corresponding voltage drop and head dissipation). Shorter runs have less voltage drops than longer runs.
Clearly, Apple (and other tablet makers) are literally pushing the edge of current draw over USB. Also, there aren't the standards for drawing 2amps that there are for phone chargers and normal USB ports.
Phone chargers have the data pins shorted with some resistance. The phones (and even the iPad!) will detect this is a 1 amp power source (technically they're not chargers the actual charger is in the device with Li-Ion) and not draw over 1 amp. The iPad will negotiate for 2.1amps with Apple's chargers and newer Macs. All devices designed to spec NEVER draw over 0.5a (standard USB spec) if they are uncertain of current availability. This is so your iPad doesn't burn up your PC's motherboard
Given the physical limits of this, the iPad charger is pretty much at the limits of power that can be done over standard USB - and pushing them. USB extension cables could EASILY result in too much voltage drop.
Firewire was FAR superior for this, since it's an unregulated, but nominally 25 volt connection (though many implementations were much lower and straight off the 12V rail; and Apple's chargers were 12V; Firewire devices had to be able to handle and use if they needed bus power, anywhere from 9 to 40 volts!). Much lower current involved. Much more complex electronic design. But if Apple HADN'T abandoned FireWire, they'd be reaping the benefits today by being able to offer much higher voltage wall chargers supplying much more power to the iPad 3 to charge.
So yeah, basically, quit complaining, even Apple has to live within the laws of physics. Either, make the battery life shorter, make the device use less power, live with the long charge times, or use a totally proprietary charger connection (or back to FireWire lol).
As for charging. Nothing kills a li-ion battery quicker than letting it totally die
Good post, I was pretty disappointed when Apple dumped the firewire charge capability. If Apple was still using the firewire charging spec, they could've easily charged the ipad 3rd gen in 2 hours or less instead of 6 hours!
The new iPad takes a longer time to charge, because it needs all the juice it can get to power that amazing display and the A5X processor. However, the 29% to 66% seems a bit odd.
Try running it all the way down, then back to when it's full a couple of times.
Try running it all the way down, then back to when it's full a couple of times.
A few thoughts on the subject
It's my take as well that the iPad 3 takes an inordinate amount of time to charge, which I understand is relative, in my case relative to the iPad 1 which took a few hrs to charge and would even charge while in use. If the iPad 3 has approx. 70% more capacity than the iPad 2, and presumably even more than the iPad 1, I could live with a trade off of increased battery life on a full charge in exchange for increased charging time, but that's not the case. I have no more battery life in my iPad 3 than my iPad 1. Just plug it in overnight, you say? Well, there are times I forget to plug it in overnight, and I shouldn't have to pay for that oversight with an unusable iPad for the better part of a day. Make sure I use the stock wall charger that came with the iPad, you say? I'll bet there are plenty of folks that misplace, or even lose their proprietary charger and must wait to replace it with another outrageously priced Apple iPad charger, or preferably, a comparable charger from Amazon that's a fraction of the price. How about this....all chargers are made to accommodate an iPhone with the correct wattage, or an iPad with the correct wattage. I'll bet it's not friggin rocket science, vendors would just rather you had to buy 2 chargers instead of one, which also isn't rocket science. And how about standard USB cords rather than "the one that came with your iPad"? Get my drift here...we're being bamboozled, flim-flammed, and downright ripped off with all this so-called "proprietary" or "incompatible" ***** we have to buy to make our $830 iPads work properly. Anyone else see a problem with this?
It's my take as well that the iPad 3 takes an inordinate amount of time to charge, which I understand is relative, in my case relative to the iPad 1 which took a few hrs to charge and would even charge while in use. If the iPad 3 has approx. 70% more capacity than the iPad 2, and presumably even more than the iPad 1, I could live with a trade off of increased battery life on a full charge in exchange for increased charging time, but that's not the case. I have no more battery life in my iPad 3 than my iPad 1. Just plug it in overnight, you say? Well, there are times I forget to plug it in overnight, and I shouldn't have to pay for that oversight with an unusable iPad for the better part of a day. Make sure I use the stock wall charger that came with the iPad, you say? I'll bet there are plenty of folks that misplace, or even lose their proprietary charger and must wait to replace it with another outrageously priced Apple iPad charger, or preferably, a comparable charger from Amazon that's a fraction of the price. How about this....all chargers are made to accommodate an iPhone with the correct wattage, or an iPad with the correct wattage. I'll bet it's not friggin rocket science, vendors would just rather you had to buy 2 chargers instead of one, which also isn't rocket science. And how about standard USB cords rather than "the one that came with your iPad"? Get my drift here...we're being bamboozled, flim-flammed, and downright ripped off with all this so-called "proprietary" or "incompatible" ***** we have to buy to make our $830 iPads work properly. Anyone else see a problem with this?
Last edited:
But Apple could easily use a spare pin on the 30-pin dock connector for +12V, and make a dedicated 12V iPad charger. If there is no unused pin, then add a MagSafe connector to iPad. Problem solved.
I travelled to Spain recently, also 110V. Took forever to charge.
Thank goodness the UK is on 240V!
Thank goodness the UK is on 240V!
Nice to know that I'm not the only one...
I don't think my iPad has seen 100% battery for the last 3-4 weeks now.
I don't think my iPad has seen 100% battery for the last 3-4 weeks now.
I travelled to Spain recently, also 110V. Took forever to charge.
Thank goodness the UK is on 240V!
Wrong!
Spain is 220V
And what is so good about 240V anyway? The US 110V is far more safer than your 240V, which charges the iPad just as slow as anywhere else in the world.
And the UK plugs are just horrendous.
Apologies, Spain is 220V. I must have got confused with the trip beforehand, which was to the US!
Three pin outlets are safer than two pin outlets. That's an absolutely irrefutable fact, so your argument that US 110V is safer than our 240V doesn't work. It makes sense if you think about it; two pronged plugs don't include a grounding prong, so you're relying on the device itself to protect you.
Simple. No idea what's horrendous about a piece of plastic either, particularly one which protects you. But hey ho.
This article explains it very clearly. It's actually quite ingenious: it can't be inserted in the wrong order; the internals automatically disconnect should the cable be pulled sufficiently hard as to detach; and it has shielding to prevent metal objects being inserted. It's also, of course, fused in plug.
http://crave.cnet.co.uk/gadgets/plug-versus-plug-49303764/8/
Last edited:
Charging is pretty freaking slow. It's no big deal though, I just do it at night or when I go out.
Good reading, but I still think the UK plug is way over engineered, just like many other great British Inventions. But that's another topic.
There's a pin for 12-48V (FireWire level), they'd just have to implement it. I said they're at the limits of USB, not that I think they should be using USB exclusively
----------
The guy is totally wrong about 110/120V supplies charging slower (the voltage and current off the adapter are identical). You're also wrong about 110/120V being safer. It's far more dangerous. To get the same amount of power (wattage) you need twice the current with half the voltage (amps x volts = watts). Current produces heat. Poor connections increase resistance. Bad connections, falling apart plugs, etc = fires in the US when in other countries they may remain perfectly safe due to the current being half for a given load.
Thus the lower voltage is much more dangerous since the risk of electrical fires due to aging wiring and connections is greatly increased.
PS the UK plugs are far from horrendous, they're one of the safest plug designs in the world. They have massively oversized lugs (good, less chance of a poor connection), they have mandatory fuses in the plug (necessary due to high current ring wired circuits in the UK, but honestly not a bad idea anyways... I'm not a fan of ring wiring but it has both pros and cons and I can see the argument for it), and the plugs are very sturdy and usually rewirable instead of molded. The sockets have been shuttered for years (just now mandatory in the US for new construction). What the heck makes them "horrendous" in your eyes. I do wish they were a twist-lock design, but they're honestly much sturdier than the flimsy blades on the NEMA twist-lock connectors. Thus, I vote the UK plug for best design in the world. NONE of the safety issues other plugs have (like the fact French plugs in German sockets will mate but not be grounded - thus why the Europlug for low-current ungrounded applications is so popular despite being so iffy!)
Last edited:
This is what will eventually push them to thunderbolt for charging. Probably sooner rather than later as I think its safe to say the next iPads battery will be the same as the current gen, or more likely a bigger, more power hungry battery.
UK plugs are great for all the reasons Markie stated. As well as being safer not only due to smaller current but because of the grounded and fused nature of the plug.
Good reading, but I still think the UK plug is way over engineered, just like many other great British Inventions. But that's another topic.
Over engineering implies that it has some un-needed features. The UK plug is what other countries should be aiming for.