Recommendations for external battery capacity for two on the PCT?

[Derek M.]

I'm new to external batteries and I'm trying to get my wife and I's electronics kit finalized for our upcoming PCT thru hike in 2015.

So far, here are all the USB rechargeable electronics items that I'm planning on us carrying (listed from most used to least used):
2 iPhone 6's (each has a battery capacity of 1810 mAh)
1 Steripen Ultra (not sure of the capacity, not stated by manufacturer)
2 Bosavi headlamps (each has a battery capacity of 700 mAh)

I expect that the iPhone 6's with be needing recharged the most (by far). We will be using them for music, audiobooks, podcasts, etc., as well as calls, text messaging, emails, internet surfing, etc. I'll bet 90% of the use will be listening to some form of audio while in airplane mode. We'll probably be listening to audio about 8 hours a day, I suspect, or maybe more (we both love long audiobooks!).

Anyway, I'm trying to get a handle on what size of external battery we will need to keep all these items juiced up, given the average time between electrical outlet availability on the trail. I'm still not sure on this and would love some input.

We will be carrying a Suntactics sCharger-5 for as long as it's practical to do so (until Northern California, perhaps?). After that, we'll be relying on an external battery to keep our electronics powered.

I've been eying the 2nd generation Anker lithium ion external batteries. They have a reported output efficiency of around 70-80%, seem relatively lightweight per mAh, and are well priced. Additionally, I hear nothing but good things about Anker's customer service.

Anyway, with all this in mind, what capacity of external battery would you all suggest? 10,000 mAh? More?

I also must consider how long it takes to recharge the battery as well, since we will only be in town for so long. I might consider getting a higher amperage charger than the 5 Volt, 1 Amp output standard iPhone charger variety if it will significantly decrease charge time while in town.

Anyway, thanks for any advice!

[Mitchell Ebbott]

The Steripen Ultra battery is 2600 mAh, according to this useful post on their site.

FWIW, I've found the iPhones really sip power when they're just being used for audio in airplane mode. I strongly recommend using headphones with a built in remote. The battery savings from not having to turn on the screen briefly just to skip or pause turns out to be significant, not to mention the convenience.

If you're carrying the solar charger for the first part of the hike, why don't you just track your usage on that part of the trail and order an external battery pack when the time comes?

[Rick M]

del

[Derek M.]

Mitchell,
Very reasonable advice all around.

We already use headphones with a built in remote, and yes, I agree, it's totally worth it.

As for seeing what our usage demands are at the beginning of the hike, then going from there… well, that's also very sensible advice.

I was trying to get a feel for what size battery I might need now for two reasons:

1. My family is wanting to buy us gear for our hike as gifts for the holidays, and an external battery would be a nicely priced item for a gift.

2. I have considered also carrying some sort of external battery even in the very beginning of the hike (SoCal) so that I wouldn't ever have to worry about the charger cycling the iPhone on/off constantly while it goes in and out of shade (I've heard this can actually drain your battery more than charge it).

If I carry an external battery at the beginning though, I may just go with a lipstick style mini one (with say 3200 mAh of capacity). Anker makes one of these that weighs in at 2.7oz and should be able to easily charge an iPhone once.

[Jeff LaVista]

Solar charging

I've never had direct solar charging while underway hiking work out in my favor. By that I mean strapping a solio or similar to the sunny side of my pack and trying to charge on the go.

As you said, the variable shade and changing angles of insolation cut the charge out and this cycling can kill your battery. Some chargers also reverse the flow and accidentally pull charge from your device and store that into it's own power bank. So fully test your solar system if you havent already.

[Jennifer Mitol]

It only has one JMT trip (24 days) under it's belt so take this with whatever grains of salt are needed….

But I found that when I stopped for breakfast and lunch I could plug the suntastics into my iPhone, or Delorme, or Nook and during that quick 20-ish minute break (or longer for afternoon naps!) was all I would need to top things off. My friends kept trying to charge up their Bushnell chargers on the go (they had storage capacity and the suntastics does not) and that never worked out – they kept borrowing my Suntastics charge panel over those breaks.

Anyway – don't try to use the suntastics on the go – just when you stop, prop it up in the sun and charge away. Worked like a champ (in the fully-exposed Sierra, of course…)

Good luck and have fun.

[BlackHatGuy]

I've got a New Trent 7000 mAh external battery pack I don't use anymore. It's in great shape, was only used a handful of times though it's a couple of years old so should still be in very good usage shape as well. Has two outputs (1A and 2.1A). Weighs about 7.5 oz.

If you think it would be useful (to use, not to try and trade or resell), pay for shipping and you can have it.

In case you were going to ask – it's been far too long since I used it to tell you how long it took to recharge and how much it recharged the iPhone I had at the time (probably a 5), but the device itself is showing a nearly full charge and I haven't had this thing plugged in for a long time, so it seems to hold its own charge pretty darn well.

[Ian]

As far as capacity goes, add another 30% to your energy needs to account for the power loss during transfer.

Your Steripen is rated for 50 liters. If the two of you treat two gallons per day total, you're looking at one in-field recharge per week.

That's 3445 mAh including the 30% loss during transfer.

iPhone needs will obviously depend on how much you use it. I can leave a 4S in airplane mode and get a week out of it. Let's say worst case scenario you want to fully recharge each phone once per week on the trail.

That's 4706 mAh including the 30% loss during transfer.

That leaves you with you with 1849 mAh to top off your head lamps if you go with a 10K mAh charger.

[Christopher *]

I used a small iGO dual AA primary external charger with proper tips to charge my iphone and my camera. This worked particularly well for me because everything else I had used AA's, so AA lithium primaries became my only power source. Anytime I hit civilization … even if I was just passing through a post office for a drop … I paused to charge everything up. One memorable example was the McDonalds at Cajon pass where the only outlet NOT in the bathroom was behind the trashcan/tray counter. The manager kindly pulled the entire counter forward so we could overfill the small outlet while devastating his dollar menu. What I can tell you is my year (2012) solar chargers worked okay through the Sierra, but after that (once the tree cover picks up) they were not very reliable, and most people started mailing them home.

The notable downsides to using primary battery charger:

1) Lithium AA's are expensive. I found a great deal on Amazon before I left, so I bought 200 and spread them out in my resupply boxes.

2) Disposable primaries are not terribly environmentally friendly. I mailed my spent batteries back home for proper disposal, but I still have the Karmic weight of all that battery trash.

3) iGO doesn't appear to still make the dual AA external charger pack. I don't know if there is an equivalent on the market, but this forumn would certainly be the first place I would ask.

One note to ease any anxiety is it is not that hard to make changes to any of your systems once underway. There are lots of good gear shops in resupply towns along the trail and nearly every hostel, hotel and motel is accustomed to getting packages from Amazon, EBay and any outdoor webstore you can name.

[D M]

I used a Monoprice 5000mAh. Worked great. The McDonalds at Cajon Pass has added more outlets inside, theres one right by the bathroom area also.

[Bob Gross]

You are never going to get anywhere with solar charging until you are able to estimate your power usage in watt-hours. Then you have to estimate your power generation in watt-hours. Only then can you begin.

Where is Nick Gatel when we need him?

–B.G.–

[Jerry Adams]

yeah, it's not the capacity of the batteries that's of interest

it's how many watt hours per day that the devices consume

you could use your device at home in the same manner you'de be using it on the trail and see how many days it takes before the battery runs out

it's hard to figure out how much capacity a solar panel would produce. Depends on how much you're in the sun.

If you had a base camp you spent many days at, a solar panel and external battery would make more sense. Charge the battery all day. Solar panel with optimum exposure to sun. Charge your devices at night.

There have been other threads on this. Hard to make the weight make sense with solar panel. On a thru hike, better to have external battery and charge it when you have access to power at a town.

[Christopher *]

"The McDonalds at Cajon Pass has added more outlets inside"

Haha. Way off topic, but that's good to hear. I knew they had to have them to do the floors and such, but it was like they were hiding them … maybe they were and there was a plan afoot that we failed to recognize. Herds of hiker-trash do tend to have a particular odor.

Back to the regularly scheduled program…

[Dan @ Durston Gear]

"The McDonalds at Cajon Pass has added more outlets inside, theres one right by the bathroom area also."

Good to hear. When we were there in May the only plugs were by the washroom and behind the TV, but we couldn't use the TV one because manager was paranoid it would wreck the TV if people plugged in there.

I hiked this year, and a lot of people seemed to be having good results in CA with solar chargers. However they mostly disappeared in Oregon and Washington due to more forests and clouds plus shorter days. CA has more opportunities to plug in than OR and WA, so if you are planning a battery pack for OR and WA I'd just use it the whole time to minimize purchases and shipping cost/hassle.

My wife and I hiked with Zebralight headlamps (2 @ 1xAA), small Nikon camera (unique Li-Ion), an iPod Touch and an iPad Mini. We never used a solar charger or a battery pack. With the long days, you'll hardly use your headlamps at all. We started with 2 AA batteries each and dropped to just one after a month. I never drained my headlamp. For the camera I carried a spare Li-Ion battery ($3 on eBay) and two was easily enough to get us through the long stretches at ~50 pictures/day. The iPad Mini was used for blogging and maps (no paper maps). It didn't have cellular internet, so we didn't drain the battery doing that. For just maps and blogging one charge was plenty but the standard charger was pretty slow in town (4 hours?). The iPod Touch was for music for my wife and it would last pretty well for 5 days or so.

If you do a lot of online stuff with your phones you'll want an external battery. If you don't, you might be able to get by without.

Charging time is a big factor, as town time is limited and precious. You don't want to be holed up somewhere for 1/2 the day because you need to charge and don't want to let your devices out of sight.

[Chris .]

Has a 10000MaH battery that I really like. The same size but a bit heavier than an S4 but the price is certainly right. It works great for me

[Bob Gross]

"Has a 10MaH battery"

I guess you know that this amount of ampere-hours is just about nothing.

It might be 10,000 milliampere-hours, which is 10 ampere-hours.

–B.G.–

[Steve K]

Those 10,000mAh batteries take a very, very long time to charge. I have a 14,000mAh battery from RAV Power (it's a great battery) and since it can only charge at 2.1A/5V it's a slow process.

Almost all of these batteries that are charged via USB top out at this maximum speed, but can charge slower if you have a slower power adapter, say a 5W instead of a 10 or 12W. So they'll take a LONG time to charge.

Here's the math:

14Ah at 3.7V is 51.8Wh

If we can charge at 2.1A/5V we can charge at a max of 10.5W. 51.8Wh divided by 10.5W is 4.9h.

A 10Ah battery is 37Wh, so can charge in about 3.5h at best.

That means, at the *very best* we should expect a larger battery pack to be charged in 5 hours, and a more standard 10Ah battery at 3.5 hours but it usually takes a bit longer to top off the last third due to the way battery charging works. If you screw up and use a common 5W USB power adapter, it'll take more like 7-10 hours to charge up your battery.

I recently bought the Unu Ultrapak Tour, which differentiates itself by advertising an exceptionally fast charge rate. There's no real secret here. It comes with a special wall wart, which is rated at 31.25W as opposed to the measly 10.5W that most chargers top out at. In theory, it means we expect to top off completely in 1.2 hours. The trade off is that it cannot charge off of USB, but it gets you in and out much quicker.

[Cameron M]

I have read all the threads and have tested several solar setups over the last three years, in the quest for a 5oz solar solution suitable for south of Yosemite. I still am unsure of the best strategy and have not hit 5 oz yet but here goes:
-A solo hiker is still probably better off with just a power bank
-Most good solar chargers like Suntactics have diodes to stop reverse battery drain
-I have never had luck with direct-to-iphone charging, I need a battery
-It is most weight efficient to use a solar cell in conjunction with the smallest battery, and top-off each night
-Remember to consider the Steripen and iPhone as additional power banks. They can power you through several no-sun days
-Back of pack charging does not work well
-The Anker 3200mah is very efficient, weighs just under 3 oz. A 18650 3400mah power bank performs almost identically
-With my power diet and sun exposure I can get by with a minimum of 2 watts of solar; the syntactics is 5 watts
-The Bushnell is the right idea but poorly implemented; 1 watt solar is not nearly enough- don't go there
-I use all apps on the iPhone including Spotify, which is a bad-voodoo app, so I make sure to "turn-it-off" each night
-My iPhone 4s lasts me three days, with more care, four
-You can swipe the camera on with the iPhone without unlocking
-I get 1.7 iPhone charges off either power bank mentioned above
-I get charge combinations of 100% Steripen Freedom with 64% iPhone, or 100% iPhone and 50% Steripen
-I am beginning to think that the Steripen Freedom charges inefficiently and I may seek an alternate Steripen model
-Dont forget that the other stuff adds up fast- wall charger, cables, whatever. 8oz for a solar cell is already a huge weight investment towards a solar strategy
-Finally- if both the Steripen and the iPhone don't get charged adequately, it is no big deal. I can manage just fine without either, and probably should just chuck the whole mess anyway.

[Rick M]

del

[Mark]

Listed my charging options on the first post in this thread.
http://www.trek-lite.com/index.php?threads/charging-solutions.486/

I prefer to use 18650 based power packs, that way i can carry extra batteries if needed.
I can also use the same cells in my torch, so it's a good solution all round.

Recently experimented with 5200mAh 26650's, 2 of these are giving my 5 days of recharging.

[Derek M.]

Cameron,
That's very good info. I have been considering the Anker 3200mAh unit which is under 3oz and looks fairly tough (and is cheap!). Seems like just charging a battery like that directly from the solar panel might be the ticket. I could charge a phone each night from the battery and still have some left for the headlamps and the steripen (though I suspect the headlamps won't need to be charged very often). Having a reliable and fuss free setup would be worth a few more ounces.

I am also like you in that I won't technically need the power. If the steripen goes down I'll have backup drops. And if the phones go down I can always just listen to the birds. And I always bring paper maps, so powerless navigation should not be an issue either.

Anyway, this is all good food for thought…

Even if this setup works for the PCT in California, I suspect I'll have to figure something else out for Oregon and Washington with a more power bank setup. As has been elaborated on a bit above, the potentially long charging time for these larger external batteries is what has me worried. I really don't want to sit around town just to babysit a battery that needs to charge for half the day.

[Cameron M]

When you get north, you could send the solar cell and the 3200 Anker home, and just use a larger Anker, many of which have fast charge rates of 1.2A., and carry a dual USB block that supports the fast rate. TIP: most lithiums charge fastest the first 60%. With limited time, just charge all devices to 60% and then head out.

Did not know about the Bosavi headlamps- they look perfect for a USB power strategy.

[Mike In Socal]

"If you had a base camp you spent many days at, a solar panel and external battery would make more sense. Charge the battery all day. Solar panel with optimum exposure to sun. Charge your devices at night."

This can actually work while hiking. I'v done it several times with a GoalZero Nomad and their 4-AA battery charger. You can charge the 4-AA batteries in about 2-4 hours when you charge the pack from the 12V output of the solar panel and not the 5V from the USB port.

[Author]

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