[pct-l] nPower PEG -- some unfortunate numbers

Sat Mar 26 03:57:10 CDT 2011

You guys use the Mophie Juice Pack Air Case?? I have one and freaking
love the thing. It can give me an additional full day of GPS usage
from a full charge.

On Sat, Mar 26, 2011 at 1:44 AM, Kevin Cook <hikelite at gmail.com> wrote:
> Thanks David
>
> Your numbers don't match mine. First, I'm not planning to be talking on the
> phone! That said, here is my math...
>
> I've done some field testing of battery life in the type of use I want from
> the phone. First, I want to run the GPS all day. I'd like to occasionally
> take photos or video with the phone (this use may go away completely if
> needed). I want to type a journal using the phone as well. Some iPod use,
> but also willing to give this up.
>
> My biggest test was on a two day mountain bike ride from Flagstaff to the
> Grand Canyon following part of the old Moqui Stage route. Anyway... I ran
> the GPS all day, took some pictures and video, listened to music a fair
> amount of the time actually, and sent some email and a FB post when I had
> signal along the way. This level us use consumed 55-60% of the battery. I'll
> assume I need at least a 75% charge everyday. It would be nice to have a
> 100% charge each day.
>
> The iPhone 4's battery is rated at 3.7V 1420mAh. The PEG is rated at 5V DC,
> 500mA or 2.5W with a 1000mAh battery. I'm not exactly sure how to convert
> nPowers specs about xx minutes is xx talk time. I'm assuming that I am only
> getting 1.5W from the device while hiking. The PEG will full it's battery
> completely in less than 4 hours. This means I should get 2 charges a day,
> perhaps 3 on longer days. Let's make a pessimistic estimate of 75%
> efficiency in the battery transfers.
>
> The PEG's battery has 3.7Wh at the iPhone's voltage (1.0Ah x 3.7V). The
> iPhone's battery contains 5.3Wh (1420 x 3.7). Accounting for the
> inefficiency of the transfer, the PEG can provide 2.78 Wh(3.7 x .75) of
> power to the iPhone's battery. It seems to me that the PEG should be able to
> provide about a half charge for each charge of it's internal battery. If the
> PEG charges twice a day, then it should provide what I'm hoping for.
>
> Obviously I've made a LOT of estimates and assumptions. Only time will tell.
> I'm not willing to use all the batteries needed to recharge the phone
> everyday with one of those AA chargers. If I can't get the PEG to work, I
> will just alter my use of the phone.
>
> On Fri, Mar 25, 2011 at 8:16 PM, David Lippke <lippke.list at gmail.com> wrote:
>>
>> Kevin, as much as I love alternative energy, I'm afraid the numbers just
>> don't work on any level for the nPower PEG.
>>
>> I've compared the power requirements per talk minute, battery capacities,
>> conversion efficiencies, etc, of the various iPhones and have mapped those
>> into nPower's stated specifications.   Those tell me that the PEG generates
>> less than 0.1 mwh per minute of walking.   I'd be happy to lay all the
>> calculations out but, at the end of the day, it only takes nPower's own
>> numbers to convict it --
>>
>> nPower states that it takes 26 minutes of walking to obtain 1 minute of
>> talking on a 3G call using an iPhone 3G.  Since a new iPhone 3G will do
>> about 340 minutes of 3G talking, give or take, that means that you would
>> have to walk for 147 hours to charge the phone (26 * 340) / 60.   So that
>> means that you would have hiked for 15(?) days carrying 11-12oz when you
>> could have gotten the same charge for less than 3 oz (iGo powerXtender + 2
>> lithium AAs).
>>
>> Looking at it economically, if a PEG costs $160 and an iGo costs < $20 and
>> two lithium AAs cost $5, this means that you could charge the iPhone 28
>> times (140 / 5) at the same price of of AA charging.    And to charge the
>> iPhone 28 times with the PEG means that you'd have to walk for 4125 hours(!)
>> or 412(?) days -- and of course the recharging efficiency will be dropping
>> all the time and so even this extreme number would fall short.
>>
>> I didn't look at the personal energy cost of carting the extra 8oz all
>> that ways but of course a "Ray-sian" calculation would do its own frowning
>> on the solution as well.
>>
>> The net for me is that the nPower PEG is a very neat idea but it just is
>> not efficient or powerful enough to warrant carriage on the basis of cost
>> effectiveness (or convenience).
>>
>> On the other hand, maybe (maybe) using it cuts landfill and pollution
>> loads and that or other reasons might make it worth it for some.  My wife
>> thinks it looks like it might be the perfect instrument -- when applied to
>> my head -- for adjusting my behavior!   :-}
>>
>> /David
>>
>> On Fri, Mar 25, 2011 at 9:05 PM, Kevin Cook <hikelite at gmail.com> wrote:
>>>
>>> I hear you John. If it doesn't work, then I'm no worse off than I am if I
>>> can't get it. Having it lets me use my iPhone for more things is all. If
>>> the
>>> PEG fails, I'll probably use one of those devices that lets you charge it
>>> from AAs. I've pretty much ruled out solar.
>>>
>>> The iPhone isn't critical. My safety won't be at risk or anything. My
>>> wife
>>> is also going, so between us, we have 2 iPhones. If we are conscious
>>> about
>>> conserving battery, we should always have one available for things like
>>> being a GPS.
>>>
>>> I mostly want the PEG so I can create a GPS trace of the whole trail. I
>>> know
>>> several hikers have already done this, but the more data we collect, the
>>> more accurately we have the trail mapped.
>>>
>>> On Fri, Mar 25, 2011 at 5:55 PM, John Abela
>>> <pacificcresttrail2011 at gmail.com
>>> > wrote:
>>>
>>> > I am still going to question the viability and reliability of this
>>> > product to keep an iPhone powered.
>>> >
>>> > Do I love the concept - heck yeah. I would even buy one IF it proved
>>> > to actually provide enough power to recharge the power-hungry iPhone.
>>> >
>>> > But, I just don't know Kevin... seems like a huge risk at this point.
>>> > You've got what... 20-25 days left to get your gear in order... and
>>> > you want to go out on the PCT with something that will have very very
>>> > little trail proveness (guess I have to make up that word).
>>> >
>>> > While I am a huge fan of solar systems, even the high dollar ones are
>>> > still risky.
>>> >
>>> > If you are planning to use your iPhone for everything you have said
>>> > you are going to use it for Kevin, it will be a primary piece of
>>> > equipment for you. Why put yourself at risk with some product that
>>> > just had a circuit board issue. We both know what that means... and we
>>> > both should know that is not something that should be screaming red
>>> > flags - considering your time line, considering the inability for
>>> > anybody to get this product under review and actual on-trail miles.
>>> > Sigh, a whole host of red flags here Kevin...
>>> >
>>> > As much as I may not like them, nor you like them, maybe those things
>>> > you throw batteries into and plug it into your device is the better
>>> > way to go at this point in time.
>>> >
>>> > Just some things to consider.
>>> >
>>> > John
>>> >
>>> >
>>> > On Fri, Mar 25, 2011 at 4:14 PM, Kevin Cook <hikelite at gmail.com> wrote:
>>> > > When I spoke with Ann this morning, she said they had a problem with
>>> > > the
>>> > > circuit boards and had to change suppliers. She said all backorders
>>> > > would
>>> > be
>>> > > out next week and that I should also be able to get one shipped next
>>> > week. I
>>> > > bet you get yours sooner than you think!
>>> > >
>>> > > I was getting pretty worried about how to power my iPhone. It was
>>> > probably
>>> > > my biggest gear concern that was still unresolved. So relieved to
>>> > > have
>>> > that
>>> > > taken care of!
>>> > >
>>> > > On Fri, Mar 25, 2011 at 12:57 PM, Halfmile <list at lon.net> wrote:
>>> > >
>>> > >> Kevin,
>>> > >> I ordered one on 9/13/10, so far it has not shipped. Your post
>>> > >> prompted me to call for an update as I have not heard about my order
>>> > >> since a 1/4/11 email. They said they had a parts problems and had to
>>> > >> change a supplier. It's suppose to ship in a few weeks.
>>> > >> -Halfmile
>>> > >>
>>> > >> On Fri, Mar 25, 2011 at 11:55 AM, Kevin <hikelite at gmail.com> wrote:
>>> > >> > Did anyone get their hands on an nPower PEG yet?
>>> > >> >
>>> > >> > Finally spoke to someone there and they said they are shipping
>>> > >> > this
>>> > week.
>>> > >> I think Halfmile had one ordered.
>>> > >> >
>>> > >> > Misspellings and typos brought to you by iPhone.
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>>
>
>

-- 
John B. Abela
www.RedwoodOutdoors.Com

In God's wildness lies the hope of the world - the great fresh
unblighted, unredeemed wilderness. The galling harness of civilization
drops off, and wounds heal ere we are aware. ~ John Muir