Briefly: NewTrent 120R extreme battery pack

[bogiesan]

http://www.newtrent.com/store/iphone-external-battery-iphone-portable-battery/powerpakxtreme.html

I've had this unit for a couple of weeks now. Its main function for me is powering my iPhone 4S while I'm using a GPS app like MapMyRide which sucks the phone's internal battery to under 20% in 3-4 hours. It's heavy at 12 ounces but it packs a huge load of energy, 12,000 mAh, which, I think is 12 full Amp hours. Complete specs can be found at the mfr's site.

Part of my tests was to run my phone down to 30-40% and see how many full charges I could get out of the NewTrent. Answer: 9 before it stopped providing a charge output implying it could recharge an iPad mini or iPad retina from 50% to full maybe 3 times.
Pros: Bombproof case, water-resistant door protects the output connections, dual USB jacks for 1Amp and 2Amp outputs, recharges quickly from a 2A USB device and not so quickly from a 1A USB jack.
Cons: Heavy, door on the output jacks is a bit flimsy, no water protection when cables are plugged in, requires odd USB charging cable ("SD," hard to find but apparently it's all the rage for non-Apple phones so I wouldn't know), remaining charge indicator is difficult to see, truly bum-numbing gray color.

Would I recommend that you buy one? Not yet. Wait for more user reviews to show up around the webs. But if you need a high capacity power pack in your hands in a few days, I don't think you'll regret spending $60. There are dozens of similar devices on the market in varying capacities and with a variety of features and conveniences. Not many are water resistant and armored like this one.

I have not examined the physics carefully or run the numbers but I think it would take about 14 days of direct sunlight to top it off using my little Goal Zero #3.5 solar collector, if it was possible at all.

[bogiesan]

A quick update:
Today I used the battery pack on my iPad 4/retina while in the backyard. Using the NT's 2A output and Apple Lightning USB cable, I was able to run Bluetooth and Wifi at full power but the NewTrent bTtery package was only keeping the iPad running at level consumption; the battery in the iPad never gained any energy.

As soon as I put the iPad to sleep the output from the NT was sufficient to add some capacity to the iPad's battery storage. After 30 minutes the iPad had gone from 25% to about 30.

After heading back inside and hooking up the standard Apple 2A mains charger to the iPad, I saw the iPad battery stays about level as long as I'm using all of the radios on the iPad, cruising the web and using the display at full intensity. As soon as I disable one of the radios, turn down the display or reduce activity, the mains adapter does, indeed, push more energy than the NT120 extreme.

So, results of this experiment are inconclusive. The NT appears to supply 2A, as promised, but it's not quite enough to replace more than the energy consumed while using an iPad 4 in a normal way. But a mains adapter does not do that much better or faster. 

I'll try another experiment using Maps or another GPS app on the iPad to see if the NT120 can keep up with the increased processing demands.

[Old Guy New Hobby]

This is an interesting post. I have an Android, so maybe you can answer a question. The old standard USB port has only 500 mA (0.5 Amp) available, and devices using it are not permitted to draw more than this. The result is that most phones have two or more charge modes. A "USB charge" mode  is 0.5 Amp. A "fast charge" mode might be 1 Amp or 2 Amp. I suppose it's possible for a phone to have different levels of "fast charge".

To resolve this, the USB spec requires the phone to query the charger to establish how much current is available. If the charger doesn't reply correctly, the phone will set itself to a USB charge rate, even though more current is available from the charger.

My Android phone reports whether it is using a USB charge or Fast Charge, but you have to dig into the menus to see this. Can the iPhone report which charge it is using? What does the iPhone report when you are using the battery pack?

[bogiesan]

sorry, I've got no clue how the device being charged knows the amperage of the USB circuit. But I know that there are two USB ports on the NewTrent battery, 1A and 2A, and, if you hook, say a power hog like the iPad4 Retina to the 1A side, it will not even see or acknowledge the power source; the charging indicator does not light up. If you hook, say, a little iPhone up to the 2A port, the phone will charge twice as fast.

If there are apps that will let a user examine the charging cycle and battery circuitry on Apple devices, I have not explored them. Interesting question, sorry I cannot be of more help.