iPad Pro IPP & 29 watt charger question

[Brookzy]

Unfortunately with 2 variables, you can't really be sure. You can assume 2A means 29W charging, but personally is rather see the voltage, as 2A can simply mean 10W charging

But the 29W charger can only output 14.5V or 5.2V. It's not like the voltage could be any figure, right? (I don't know, I'm merely asking).

 

[masotime]

But the 29W charger can only output 14.5V or 5.2V. It's not like the voltage could be any figure, right? (I don't know, I'm merely asking).

Yup. So if it says 2A, it could mean 2A x ~5V = ~10W. Current is not really a guarantee. However at 14.5V, it must be charging at 29W

EDIT: to clarify, the 29W charger outputs 10/12W when running at 5V.

 

[zhenya]

But the 29W charger can only output 14.5V or 5.2V. It's not like the voltage could be any figure, right? (I don't know, I'm merely asking).

Yes, it's variable. The power drawn by the device depends on the charge state of the battery; drawing the most power when the battery is low, and gradually tapering off as the battery fills. A more powerful charger, like the 29w one, when used with the 12" iPP gives some headroom so that the battery can be charged at full current while also providing power to the device, unlike the included charger where the charge rate may slow to a trickle or even reverse if the device is under heavy load.

 

[chabig]

Chargers maintain a constant, regulated voltage. The connected device draws a current, which varies depending on demand. Meanwhile the charger's job is is to deliver that current while maintaining the regulated voltage. A charger capable of delivering higher power is capable of delivering higher current.

 

[Brookzy]

Yup. So if it says 2A, it could mean 2A x ~5V = ~10W. Current is not really a guarantee. However at 14.5V, it must be charging at 29W

EDIT: to clarify, the 29W charger outputs 10/12W when running at 5V.

But you can tell within a couple of minutes if it's fast charging (assuming charge is below 80%).

Yes, it's variable.

Chargers maintain a constant, regulated voltage.

😕

(I'm pretty sure @chabig is right though.)

 

[zhenya]

😕

(I'm pretty sure @chabig is right though.)

Voltage is constant but current, and hence watts, is variable.

 

[Brookzy]

Voltage is constant but current, and hence watts, is variable.

Then re-read my query: if voltage is constant then the Battery Life app is perfectly sufficient for measuring charge power despite its lack of a voltage reading!

 

[masotime]

Then re-read my query: if voltage is constant then the Battery Life app is perfectly sufficient for measuring charge power despite its lack of a voltage reading!

Yes, but you have no idea what that constant is. It could be 5V or 14.5V. If you try to guess based on how fast it is charging, then you don't even need an app at all do you?

More specifically, it is constant during the charging process. Something being constant is not the same as being fixed (to 14.5V in this scenario)

 

[Brookzy]

Yes, but you have no idea what that constant is. It could be 5V or 14.5V. If you try to guess based on how fast it is charging, then you don't even need an app at all do you?

?

Of course you know what the constant is. If you're charging using the USB-C solution on a 12.9" Pro, it's charging at 14.5V. There's no reason for it not to.

 

[masotime]

?

Of course you know what the constant is. If you're charging using the USB-C solution on a 12.9" Pro, it's charging at 14.5V. There's no reason for it not to.

That is not true actually. At >90% it drops to 5V. The point is that you can't verify that it is charging at that speed. If you don't care to verify, it doesn't matter of course.
[doublepost=1460916050][/doublepost]

There is an app called Battery Life that shows charging current in mA, and I'm no electrician but if you know the charging voltage (I think it's 14.5V on the 29W USB-C charger?) you could do P = IV to work out the charging wattage?

Ah ok, I see my mistake. You're just trying to work out the wattage assuming that you know it is 29W. Ok yes I agree with your point. I had assumed the intent to was verify it was even fast charging with absolute certainty.

 

[rasputin1969]

I'm not defending Apple here, but don't forget how strong the $ is against the £ at the moment.

I'm not. 1$=£0.7 so $35 should be £24.5. Add VAT and you should have £29.4. Daylight robbery, Apple have no excuse for this.
[doublepost=1460921042][/doublepost]I have a quick question regarding the fast charger. Will google's 60w usb c charger work with fast charging on the iPad Pro 12.9?

 

[Brookzy]

Will google's 60w usb c charger work with fast charging on the iPad Pro 12.9?

Now that's a good question - you would expect it would definitely work but Apple states "You might not be able to charge your iOS device using USB-C power adapters that aren't manufactured by Apple." Hopefully someone has one to try it out. In the meantime I'm trawling Google! 😛

EDIT: Apparently the Google 60W USB-C charger only supports 5V/12V/20V over 3 Amps. The fast charging requires 14.5V and 2A. @masotime: Does that mean that the iPad will take 12V and up to 2.41A to make up for the lower voltage, or will it fall back to 5V (and therefore charge slowly)?

 

[Southern Dad]

 

[masotime]

EDIT: Apparently the Google 60W USB-C charger only supports 5V/12V/20V over 3 Amps. The fast charging requires 14.5V and 2A. @masotime: Does that mean that the iPad will take 12V and up to 2.41A to make up for the lower voltage, or will it fall back to 5V (and therefore charge slowly)?

Unfortunately it depends on how the iPad negotiates with the charger to set the voltage / current. Actually now that I see @Southern Dad's screenshot, I'm pretty confused. The iPad Pro isn't supposed to charge at a high current, so I'm not sure what's going on now with how it charges. Possibly the app itself is able to read the charging power and is erroneously dividing it by 5, since 5.3A * 5V = 26.5W, which makes sense if it is charging using the fast charger.

 

[Southern Dad]

Unfortunately it depends on how the iPad negotiates with the charger to set the voltage / current. Actually now that I see @Southern Dad's screenshot, I'm pretty confused. The iPad Pro isn't supposed to charge at a high current, so I'm not sure what's going on now with how it charges. Possibly the app itself is able to read the charging power and is erroneously dividing it by 5, since 5.3A * 5V = 26.5W, which makes sense if it is charging using the fast charger.

Can't speak to the electrical math of it, but it certainly charges much faster with the 29 watt versus the 12 watt that came with it. I am very happy with my purchase. It was worth every penny. One of my complaints was how long it took to charge the iPad Pro 12.9", not any more.

 

[rasputin1969]

So the apps not reporting the correct figures and you're not using the google 60w charger.

 

[TrueBlou]

Well it's nothing that's not been said before, it's nothing I didn't know beforehand and its blindingly obvious. But my USB-C cable finally arrived today so my 29W charger is no longer lonely and bloody hell is it quick.

Obviously I knew what to expect but I don't know, seeing it in the flesh is just something different to reading about it I guess. I'm really pleased I decided to spend a stupid amount of money for a charging setup. Went from 39% charged to 100% in 1 hour 19 minutes. Now I just need to drain the bugger to see what a full charge takes 😀

 

[Southern Dad]

Well it's nothing that's not been said before, it's nothing I didn't know beforehand and its blindingly obvious. But my USB-C cable finally arrived today so my 29W charger is no longer lonely and bloody hell is it quick.

Obviously I knew what to expect but I don't know, seeing it in the flesh is just something different to reading about it I guess. I'm really pleased I decided to spend a stupid amount of money for a charging setup. Went from 39% charged to 100% in 1 hour 19 minutes. Now I just need to drain the bugger to see what a full charge takes 😀

I felt the same way. It is impressive.