[pct-l] Apple iphone Charging

[Tobin Van Pelt]

I have seen lots of Apple Iphone Charging banter so I though I would  
summarize my experience here:

I was on the PCT for 5 months this year and was able to charge my  
iphone 3G with both a solar panel as well as a backup battery.  People  
should know that Apple uses complex handshaking on some of the USB  
pins to negotiate a charge cycle.  This extends the life of the  
battery and allows it to operate more efficiently.  The key here  
though is that you cannot charge an iphone by just placing a load on  
the power terminals of the USB connectors.  The charger has to be  
engineered for the Apple iphone device or it will not charge.  Many  
companies claim to have chargers for iphones but they do not work  
(amazing how many marketing departments jump to the conclusion that  
since the connectors are the same that is must work).  Beware here  
especially if using one of the newer iphone models such as a 3G  
device ... the electronic logic has changed even further.  (It is my  
judgement that this is not a sell you more stuff strategy ... there  
are actual good engineering design reasons why they use sophisticated  
implementations).

Here is what I had success with on the PCT this year:

1. Power Film USB solar charger - http://www.powerfilmsolar.com/products/portable_remote/index.php?cat=pr_usb

This solar panel was quite durable, and would fully charge 2 AA  
batteries most days on the PCT (sunny) in about 6-8 hours.  There are  
two concerns here though.  First, the 2 AA battery capacity in the  
solar panel only charges half of a full iphone 3G.  Second, there is a  
logic issue in the DC-to-DC controller of the Powerflim during  
charging for the iphone.  When the AAs get close to depleting, the  
iphone disconnects.  Once this load is removed the batteries rebound  
(voltage comes back up), and then the iphone comes back on pulling the  
voltage down again.  The net effect is at the end of the charge cycle,  
the iphone repeatedly oscillates between charge and no charge.  I was  
able to just watch the charge cycle and disconnect as soon as it got  
to that point to avoid any long term wear and tear.  The iphone  
charges very rapidly off of the AAs so this was never a huge issue.  I  
spoke to the company in detail about this (I was actually testing the  
product for them) and they are aware of this and likely addressing  
this in the future.  I adjusted all settings on my device to maximize  
battery life for the trail (look online there are several overviews on  
how to tune your device for the particular use to extend battery life  
- such as lower screen light, turn off 3G, turn off push/pull of  
email, etc). While using GPS, several iphone apps, and leaving edge  
network on, I never drained a charge faster than once in every two  
days.  So leaving the Power Film on top of my backpack while  
hiking ... I was able to keep my device charged

2. 3G Juice iphone battery - http://www.3gjuice.com

This guy performed amazing well!  Would fully charge my iphone (and  
even had a little charge left over) from one battery.  Very light  
weight and small.  I carried a couple of these and they performed  
incredibly well in cold and hot temps.  Never had one fail.

In the end - it was more work and more hassle to use the solar panel  
at all.  Because you will be getting resupplies every 3-4 days usually  
- a fully charged phone and two backup 3G Juice batteries get you  
through. The only exception is through the high sierra will you will  
likely want something like the solar panel to get you through.  But  
then again you won't be using phone or SMS so you could just  
completely turn those off and possibly extend the iphone for 4-5 days  
on a full charge (even with a few photos thrown in).

One last thing to think about ... consider getting an otter box case  
defender case for the phone - http://www.otterbox.com/iphone-cases/iphone-3g-3gs/iphone-3g-3gs-defender-case

Water resistant, and shock absorbing this product was amazing as  
well.  I got home, took my iphone out and it looked brand new!

Hope this helps you iphone users on the PCT!

Rocket Man
PCT-09