Best way to charger your smartphone on multi-day walks ?

[anthon...@gmail.com]

Hi,

As one of many people who have switched to using a smartphone as their primary bushwalking GPS, I was wondering what people out there do to power their devices on multi-day hikes ?

The old Garmin eTrex used to have 24 hour battery life, plus you could take as many spare batteries as you needed, but most smartphones are lucky to be able to run in GPS mode for one day before the battery is empty.

I've been searching the web for ideas and these are some of the options I came up with:

* Spare battery (for phones which allow you to change the battery)
* External battery bank
* Solar charger
* Fuel cell charger (Hydrogen)
* Hand-turned winder for charging
* Motion charger (e.g. The Ampy)
* Cooking pot charger that uses a thermocouple

A spare battery or external battery bank is the most simple, of course, but what about for trips longer than just a few days ? A solar charger is obviously the most simple for unlimited recharges, but what if you don't have enough day-light hours in the same spot to charge up ?

What are people out there using and what works ?

Thanks,
Anthony.

http://www.binaryearth.net/HandyGPS
http://www.diamondspirit.net/adunk/

[David Morrison]

In article <521c8e8d-b43c-4ad5...@googlegroups.com>,

All good questions Anthony, but at this stage I am not sure there is an
answer. The big problem is that modern smartphones take a *lot* of power
to charge up. With most of the practical solar chargers, you need
several days of sunshine to charge a phone iirc. A hand-turned winder
would have you exhausted before the phone was charged. I suspect your
best bet would be an external battery pack and be sparing with your use
of the phone.

One of the complications is that you are not just using the GPS, but
also the radios. When you are out of range of a mobile network, your
phone sends out as strong a signal as it can to try to reach one. This
will chew through the battery. And if you turn it to Flight Mode, that
also turns off the GPS (on iPhone anyway, maybe on Android too).

It seems unlikely to me that smartphones will be of any use in the bush
except for the occasional location checks.

[ma...@wildwalks.com]

Hi Anthony

hope you are well.

I run through stacks of power when walking for work. I carry Li-ion battery packs for charging. For smartphone & camera 300grms of battery gets me about 4 days no worries -- can easily double that if I start taking care of power management (ie airoplane mode etc).

I have tried most stuff. I think fuel cells is the best looking option. I have tried one and batteries was lighter -- but this bit of technology looks like it finally wins that game. (not yet available but soon)
http://hellokraftwerk.com/

This produce a lot of power, but slowly. I have big power needs for come of my camera rigs, but if I run one of these constantly charging a larger battery, I can get weeks out of a small gas cylinder. So I am keen on this.

I wrote this article http://emag.bushwalk.com/BWA201502.pdf (page 70) on the topic -- hope that helps.

If you want to borrow one of my batteries, just give me a yell.

Matt :)

[Adrian Jansen]

At least on Android phones you can switch to Flight mode to turn off the
phone cell radio systems, then switch the GPS back on.

But beware that many mapping apps leave the GPS on in the background
after starting, and some even when shut down, using even more power.

Also most phones I have played with do a very poor job of getting a fix
when no A-GPS is available ( which of course needs a data connection ).
So while taking the extra time to get the fix, even more power is being
used running the GPS and computation algorithms.

Personally I would go back to using a proper handheld GPS to do
navigation. At least its optimised for that. And overall, which is
less weight, a GPS and a phone, or a smartphone with poor GPS capability
and a big bunch of batteries ?

[anthon...@gmail.com]

> One of the complications is that you are not just using the GPS, but
> also the radios. When you are out of range of a mobile network, your
> phone sends out as strong a signal as it can to try to reach one. This
> will chew through the battery. And if you turn it to Flight Mode, that
> also turns off the GPS (on iPhone anyway, maybe on Android too).
>
> It seems unlikely to me that smartphones will be of any use in the bush
> except for the occasional location checks.

No, this is only true for iPhones. Android phones do not suffer this issue since you can have the GPS receiver turned on when they're in airplane mode.

I kind of wonder why Apple doesn't fix this issue with iPhones, but perhaps they don't hike often :-(

Here's what my research about this topic previously led me to as a work-around:

"When an iPhone is out of cell tower range, it uses a lot of battery power transmitting "pings" to try and connect to a cell tower. Generally, to save battery power in such circumstances you can just put the phone in "airplane" mode. However, on iPhones airplane mode also turns of the GPS receiver. So, if you really need to extend battery life when using HandyGPS in remote areas, your only options are to either physically remove the SIM card or to lock it using a PIN code. However, if you're going to use a SIM PIN code, make you sure you know what it is first, otherwise your phone will lock and you'll be unable to make calls!"

[anthon...@gmail.com]

> I wrote this article http://emag.bushwalk.com/BWA201502.pdf (page 70) on the topic -- hope that helps.
>

Awesome. Thanks for the link! It looks like a pretty comprehensive coverage of the topic.

I'd really like something that generates power while you walk, like the Ampy, as I think that is simplicity itself. But I think for fuel cells, one that runs on a liquid like pure alcohol would be nicer than hydrogen because you can easily store the fuel in a bottle and see how much you've got left.

Since you're an iPhone user, check out the SIM card work-around for the iPhone power loss issue when out of signal range. (See my other post here) It's a real fiddle, but apparently it does the trick.

[maso...@gmail.com]

The above information is out of date.
Since iOS 8.3 the iPhone GPS receiver is still active when the phone is set to airplane mode.

With an iPhone 6 set to airplane mode using Avenza PDF maps with the NSW LPI 1:25,000 sheets I'll use about 10% per day of the battery. My mates' GPS batteries run down much faster.

[David Morrison]

> Here's what my research about this topic previously led me to as a
> work-around:
>
> "When an iPhone is out of cell tower range, it uses a lot of battery power
> transmitting "pings" to try and connect to a cell tower. Generally, to save
> battery power in such circumstances you can just put the phone in "airplane"
> mode. However, on iPhones airplane mode also turns of the GPS receiver. So,
> if you really need to extend battery life when using HandyGPS in remote
> areas, your only options are to either physically remove the SIM card or to
> lock it using a PIN code. However, if you're going to use a SIM PIN code,
> make you sure you know what it is first, otherwise your phone will lock and
> you'll be unable to make calls!"

Interesting. I guess then it comes down to how much power the GPS will
use without the radios operating, ie, how many hours of GPS can you have.

otoh, removing the SIM out in the bush could be a risky business. Drop
it or lose it in a pocket and your phone is useless as a phone.

[anthon...@gmail.com]

> The above information is out of date.
> Since iOS 8.3 the iPhone GPS receiver is still active when the phone is set to airplane mode.
>
> With an iPhone 6 set to airplane mode using Avenza PDF maps with the NSW LPI 1:25,000 sheets I'll use about 10% per day of the battery. My mates' GPS batteries run down much faster.

Thanks. That's great news !

I found the following official info from Apple which appears to confirm it:
https://support.apple.com/en-us/HT204234

It says "If you have a device with iOS 8.2 or earlier, Airplane Mode will also turn off GPS.". So by implication, iOS 8.3 and greater does not disable GPS in airplane mode.

Anthony.

[anthon...@gmail.com]

I ended up buying an Ampy Move motion charger and trying it out over christmas. I was pretty disappointed that it didn't really charge much when walking - you have to be jogging for it to charge by any significant amount. So I sold mine on eBay and just bought a light $20 Comsol 2200 mAh battery bank instead.

You can see a review about the Ampy here:
https://www.youtube.com/watch?v=bQcJP9xXH-M

[David Morrison]

In article <562ebd5a$0$1510$c3e8da3$5496...@news.astraweb.com>,

Adrian Jansen <adr...@qq.vv.net> wrote:

> Also most phones I have played with do a very poor job of getting a fix
> when no A-GPS is available ( which of course needs a data connection ).
> So while taking the extra time to get the fix, even more power is being
> used running the GPS and computation algorithms.

I was surprised to find recently that my iPhone SE, when the radios were
off, only took a few seconds to get a GPS location. This was faster than
any dedicated GPS I have used, although that was a few years ago.

[Adrian Jansen]

Yes, the current crop of phones seem to be a lot better. My Sony Xperia
Z5 also gets a fix in around 20 sec or so without a data connection.
Huge improvement in the last couple of years.

--
Regards,

Adrian Jansen