External Batteries – 2015 Market Review

The 6th most-read page on the site is the Jan 2014 guide to choosing an external USB battery so I thought it would be a good idea to revisit the topic in early 2015 and expand and improve everything while I was at it, enabling readers to make an even more informed choice.

If you want to read the original article just click here. It does a good job explaining what external USB batteries actually are, what they are used for and why hikers, especially long-distance backpackers, find them useful. If you want to jump straight to the comparison table of this article click here.

I don’t want to duplicate content but rather build on that article using my experience of hiking 730 miles (1175 km) of the Appalachian Trail recently in terms of how to go about choosing the best external USB battery and review a much wider range of actual products available today. I reviewed the specs of over 170 products to arrive at the shortlist detailed here. I include the key specs of these in an interactive table to allow for easy comparison.

USB batteries are much – much – easier to choose than almost any other piece of hiking gear. It is a block of plastic and/or metal housing some electronics and the actual lithium battery (which itself is almost always manufactured by LG or Samsung). You charge it up from a wall and in turn it will charge up your devices via USB ports and your own cables. Big deal, nothing complicated here. They mostly all work just fine and there are practically no compatibility issues (a veritable miracle in the worlds of computing and electricity!). This is not the time to become emotionally attached to a brand or an individual product; this is the time to compare the key specs and make sure you get the best battery for you, period. Even the price of most of these products shouldn’t create any stress.

Market changes in the last year

When I carried out a similar review of the battery market in late 2013 I found very few products boasted an input capacity of more than 1 amp, even in the larger batteries above 10,000 mAh. This has thankfully improved and it is now a sign of an outmoded product due for an update if it still offers this level of input.

The capacities available have increased in size, and 12,000-14,000 is now quite normal. This is probably due to a combination of two factors: increased awareness and popularity with consumers and a greater requirement in the devices to be recharged. While you may wish to recharge a wide range of devices the number one type by far is the ubiquitous smartphone. The internal battery capacity of these has rocketed in the last 18 months and a high-end phone now is likely to boast a larger screen and a battery in the 2,000 – 3,000 mAh. They still need recharging as much as their smaller ancestors though and thus the USB battery market has gained greatly in popularity. People that didn’t even know what they were a year ago now routinely carry them in their bag on a daily basis.

A weight-conscious long-distance hiker might now start to consider whether the best smartphone for them is actually an older model and not the latest flagship.

Scope of review

To set the stage for what I am reviewing here, I am looking at medium capacity (8400-12000mAh) external USB batteries (sometimes called powerbanks) for multi-day 3-season weight-conscious hikers that provide supplementary power (charge, juice) to personal electronic devices including all smartphones, most tablets, GPS devices, eBook readers, some headlamps, all music (MP3) players and other such small modern digital devices. There are literally thousands of USB batteries on the market and many are suitable for a target audience other than this scope.

These batteries are simply recharged from a wall plug (or car if you want). There are batteries that use  other methods  of charging (often in conjunction with wall charging), namely solar chargers, hand (crank) chargers, heat exchangers (i.e. driven off a stove such as wood-burner like the Biolite) and even gas-powered fuel cells (see the interesting Kraftwerk project on Kickstarter which raised $500,000 in the first week alone and may be potentially useful for hikers in 2016 or 2017). This article does not cover those as they really require an article to themselves. Also, they are simply not efficient on the Appalachian Trail specifically – the weight is better spent on more battery. If you are considering one be sure that you understand the weight you are “paying” in order to get the unique feature and judge if that is worth the “cost”. For example if a battery with a solar panel attached is, say, 100g, more than an equivalent non-solar variety then is it worth 100g to you? You could just “spend” that 100g on more  capacity in a regular simple battery and not have the hassle of solar charging at all.

Do remember that the field of consumer electronics is fast-changing and you will find products listed here that are not available when you come to check them out, or have been updated, or renamed, or what-have-you. And of course new products and brands come to market all the time. The main idea of this article is to show you how to objectively rate a potential purchase and not be swayed by marketing fluff or a mention on Facebook from someone with experience of just one product, which  is invariably “amazing”. The simplicity of USB batteries is such that people seem to frequently be amazed by their purchase, as testified the number of 4-5 star reviews for a huge number of batteries on Amazon. As backpackers we need to be more savvy than general consumers and understand more of the details to make the best  purchase possible.

To make an objective comparison between the products considered ‘in scope’ I will take the following specs, features or factors into consideration: capacity, weight, size, input rating, outputs and their rating. Price will be listed but the actual importance of cost is down to your own personal choice since it has no affect on the the product itself. Generally speaking, prices are all in a $20-$50 range except in one extreme case, Mophie, which deserves highlighting as this brand is on a whole different level for no apparent reason.

These are what I consider to be the key features that should influence a weight-conscious hiker when purchasing an external battery. For example, I don’t pay any attention to ‘tough‘ or ‘rugged‘ features like shock protection or water resistance. In fact such a feature will almost certainly cause the product to be absent from this review since the extra weight is too burdensome. I never had any problems keeping my battery protected in my pack during the day – it didn’t have its own bag or ziplock, it was just in my ‘bits and pieces’ or ditty bag and it was only ever  used inside my tent each night. No need for lots of extra weight protecting it from being used as a frisbee, and for $20 you can always just buy another one. An LED torch feature could be useful – I certainly found it to be so – but I would treat it as a backup light rather than your one-and-only. Even for complete gram weenies I would recommend a dedicated light such a Petzl e-Lite for 27g (0.95oz) rather than waving your USB battery around a dark camp trying to hang a bear bag. Trust me on this. Charge-through is a rare feature that allows you to charge up a device that is plugged into your battery while the battery is being charged from the wall. It always comes with restrictions and will not magically power up both the battery and the device(s) at the same speed as charging them separately. If you really want to do this then it is more functional to take an adequately-specified  dual- (or triple- or…) USB wall charger and charge everything at 100%.

So here ARE the factors that are being rated. The specs are gathered from the most reliable source possible and preferably cross-verified from another source. I tried never to rely solely on manufacturers claims and instead looked for reviews from respected review and retail sites like Amazon, bloggers, You Tube videos, etc.

Capacity: how much power it stores, measured in milliampere hours (mAh). This is a “leading” factor, meaning your choice here will drive all the other factors. For example, if you want a high capacity battery then you must expect it to be heavier, larger and more costly on average than a battery with less capacity.

Here are the internal battery capacities of some of the most popular high-end smartphones on the market right now. To find out the capacity of your particular device check your manual or just Google ‘devicename battery capacity’. As you can see there is a vast difference in capacities between just phones, let alone different kinds of devices, so you need to be clear what your particular devices have and how important they are to you to keep charged up.

Smartphone battery capacities

Smartphone
Capacity (mAh)
Apple iPhone 51440
Apple iPhone 5c1507
Apple iPhone 5s1560
Apple iPhone 61810
Apple iPhone 6+2915
Samsung Galaxy Note 43220
Samsung Galaxy S42600
Samsung Galaxy S52800
Motorola Moto G22070
Google Nexus 52300
Google Nexus 63220
Sony Xperia Z13000
Sony Xperia Z23200
Sony Xperia Z33100
HTC One2300
HTC One M82600
Nokia Lumia 9302420

You will want to use your external battery to charge one or more of your devices. In order to choose a sensible capacity you need to know the battery capacity of your own devices and figure out how frequently you will want/need to recharge them. For example, someone might have a 2500mAh a smartphone (important, frequently used, lasts 2-3 days with typical usage when hiking) and a 800mAh digital music player (unimportant, small capacity, lasts 1-2 days with typical usage. Those two together are 3300mAh but you may discount the music player as just ‘nice to have’ and decide you need two full charges of the smartphone to get you to the next town, meaning you want 5000mAh capacity (but actual capacity not quoted capacity – see charging efficiency for details).

Beware of the common way that manufacturers mislead unwary customers by simplifying all this down to a “number of times it will charge a smartphone” figure, like the Mophie Powerstation Plus range using “2x” prominently to indicate “up to” 2 smartphone charges from their 3000 battery, which stretches the meaning  of “up to” to new levels of stretchiness if you own a Samsung Galaxy S5 phone as it will only give you 0.75 in reality. Ignore their claims and work out your own requirements for your own devices.

A quick word on device capacity, in particular on smartphones. A larger internal battery (e.g. the Samsung Galaxy S5 at 2800mAh versus the iPhone 6 at 1810) means that it requires more power from an external battery to recharge. It may, or may not, mean that the device works for more time. Generally speaking most manufacturers aim for their smartphones to last comfortably for one day of typical ‘urban’ usage, which makes sense – why burden a product with a more expensive, larger, heavier battery when 90% of users are happy to charge it fully each night? A larger battery capacity does not automatically mean the phone it powers will last longer than the phone with a smaller battery. There are a great many factors in how long a phone lasts of which internal battery capacity is but one. However, the internal battery size does have a perfect correlation with how much power it will require from an external battery to recharge it. A 2000mAh battery will charge 100% of an early model iPhone but only 50% of a Galaxy Note 4. You may find a large-screened all-powerful ‘phablet’ to be very useful in your ‘normal’ life, but when hiking in the backcountry for days on end it may not be the best choice, but of course it all comes down to what you personally want and whether you are willing to pay the price in weight.

Charging efficiency: This is the percentage of power that an external battery actually is able to supply a device when charging. Yes, this is not 100% due to inefficiencies with the process such as loss of power to heat. It is usually 60%-75% but a few products might be a bit worse, or rarely get up to 80%. Unfortunately you will have to ignore the manufacturer’s claims for this number as they are not accurate. Once you get a device in your hands you can measure it for yourself by charging a large capacity device such as a tablet, or a phone multiple times until it drains your external battery from full to empty. Then just tot up the % of your device that it managed to charge and multiply that by the device’s capacity (this works best when your device’s battery is new as they can start to hold less and less charge as they get older). For example, if your 3000mAh battery supplied your iPhone 5 with, say, 150% of total charge, then it supplied 1440*1.5 = 2160mAh of juice. Since it was a 3000mAh battery it must have a charging efficiency of 2160/3000 =  72%. Actually it’s probably only useful to remember that it can supply 2160mAh of power, the percentage isn’t really useful. Write that number down somewhere (on the battery if you like) and then you can figure out accurately how you want to distribute the remaining power when it gets down to 50% and you have a phone at 30% and a Kindle at 12% and you’re two days from civilization.

Unfortunately it isn’t possible to include this spec on the ratings table since I would have to purchase every product on the market and test them. Even other people’s reviews are notoriously inaccurate as most people have no idea how to measure the actual useful capacity (actually, most people don’t seem to realize there is even such a thing) and will leave their device on when recharging it, etc.

Weight: measured in grams as an absolute measurement. This is a critical factor for backpackers as an absolute number but it also drives the “mAh per gram” factor which measures weight efficiency. In order to save space in the table, Americans will have to convert grams into ounces themselves. Life is hard.

mAh per gram (m/g): This is really the single most important spec because it lets you compare different products using a common measurement. Is that 10,000 battery relatively as weight-efficient as the 8,000? As a general rule the smaller the capacity of the battery the more weight has to be lost to hardware (electrical components, electronics, the casing, ports, etc.) while larger capacity batteries should consist of a greater proportion of actual battery so you should be looking for better values in bigger batteries, while accepting lesser numbers in smaller batteries. The key thing is to choose one near the top of its class. Note that I quote this figure based on the maximum quoted capacity of the battery rather than the ‘real’ available capacity after the Charging Efficiency is taken into consideration due to the spotty availability of that metric.

Size: stated in width x length x depth in centimetres and then volume in cubic centimetres (CCs). Many people will not care whether it is a longer, thinner battery, or a more cuboid shape, but the total volume used (CCs) lets us compare all the products consistently. A few extra CCs won’t matter in most circumstances but at the same time you don’t want to waste space if you can help it.

Input: how many amps does the battery accept into it, from the wall (or car) charger/plug. You only ever get one input port and it’s almost always Micro-USB in type. The more the merrier as a higher input rating will charge a battery up faster than a lower input rating assuming the power source does actually provide the higher rating. This spec can be an extreme differentiator as some popular products only accept a 1 amp input compared to others that accept 2 amps or even more, thus potentially charging up twice as fast – a huge factor especially in larger-capacity batteries. For example, a 12,000mAh battery with a 1 amp (which means 1000 milliamps) input would take at least 12 hours to recharge (at best, again an inevitable loss of efficiency will probably slow that down even further) while a 2 amp charger would only need 6 hours. Just be sure that your wall plug actually provides the same number of amps, or more, than the input rating of your battery – no point carefully choosing a battery with 1.5 or 2 amp input and then using a 1 amp wall plug  to charge it. So the weight and size of both the charger and the battery as a pair should be considered, not just the battery. You might find the faster 2 amp charging route is quick but you have to ‘spend’ more  weight than ideal to get a good enough charger. A follow-up article on wall chargers is on the cards to cover this important topic…

Output ports: number of ports into which you can plug a cable and charge a device. I focus on two-port batteries in this review simply because most medium-capacity batteries feature two but one port is often adequately useful so having just one  did not exclude any product from being reviewed. Four ports is a niche use case (family camping for example), and the extra weight and size (and extra cables) intrinsically needed means it is not suitable for inclusion in this review that is focused on weight- and size-conscious hikers.

Output rating (amps): each output port preferably needs to give out enough power to charge up your device at the maximum speed it supports, meaning the output rating of the battery needs to match or exceed your device’s input rating. It is safe to exceed that by the way, so a 2 amp output port on your battery is safe to use on your 1 amp phone, for example. You will have to check your device’s manual for what it takes but one common example is an iPhone 5s or earlier takes up to 1 amp, iPhone 6 or above can take 2.1 amps.  If the battery output port provides less amperage than your device can handle then it ought to still charge, but at a proportionally slower rate, e.g if you plug in a tablet that takes 2 amp input into your 1 amp battery port it will charge up at half the speed you may have been used to at home using a 2 amp wall charger.

Price:  What does it cost, in US dollars. Again, price didn’t preclude any products from being included and it has NO impact on my reviews, you must read my opinions with the understanding that I am being deliberately price-agnostic – you’re a grown-up, you can make your own value judgement at the end without me introducing personal bias which ruins the review. I don’t let borders preclude any product from being reviewed here, as long as I find at least one decent-looking website selling it that offers international delivery. I figure if you really want something then you can click a couple of buttons and wait for it to be delivered and you’re capable of including delivery charges when making your own personal value judgement. For fellow Brits you can find the majority of these products from UK retailers, though prices here may be slightly higher than the dollar amount listed; just use Google and Amazon.co.uk to do your own research. Finally, I wouldn’t recommend buying second-hand products, e.g. from Ebay or privately, as battery capacity and performance tend to degrade over time and the prices of these products should allow them to be purchased new.

 

The table below shows the key specifications for all the ‘worthy’ contenders on the market today (January 2015). What does ‘worthy’ mean? It means a product that is worth considering because it’s specs are in the top tier, and/or that the product is from a popular manufacturer and not including it might  cause confusion. You can then see how the well-known products compete in the market on the hard facts alone. Almost all manufacturers offer more than one product, sometimes the difference being just the capacity but sometimes they have multiple differences. I haven’t included EVERY product therefore as the table would literally be hundreds of rows long and I could never hope to maintain it but I have cherry picked and if, say, a 12000mAh battery is listed here and you only want a 10,000 you should definitely check the manufacturer website as it’s quite likely they offer that size and it will likely be of comparable specs if it’s in the same range.

If you find a product that has a m/g spec of at least 42 and at least one output of 2.0 amps do let me know via a comment on this article or use the Contact form in the main menu above. And of course if you can point out any inaccuracies or add extra details to any part of this article please do the same.

USB Battery Comparison Table
Manufacturer
Model
Capacity (mAh)
Weight (g)
m/g
Dimensions
Volume (CC)
Input (a)
Output
Cost ($)
EasyAccTransformer900019745.76.3x10.5x2.4158.82.02 (2.0 / 1.0)30
EasyAccBrilliant1000024141.57.1x13.3x1.6151.11.52 (2.1 / 1.5)27
PowergenUltragen900019845.76.5x11.1x2.25162.31.53 (0.6 - 2.0)20
PowergenVitalgen1200024648.78.3x9.6x2.25179.32.03 (2.0/2.0/1.0)40
AnkerAstro 2nd Gen Astro E31000023043.56.6x13.5x1.6142.62.02 (3amp total)23
AnkerAstro 2nd Gen Astro E41300029643.96.2x15 x2.2204.62.02 (3amp total)40
UnuSuperpak1000024940.07.87x8.9x2.3160.22.42 (2.1 / 1.0)40
APCMobile Power Pack1000027037.08.8x14.6x1.3167.01.52 (2.4 / 1.0)55
JackeryGiant+1200029540.77.9x10.9x2.0174.41.52 (2.1 / 1.0)40
ZendureA3900022040.96.2x9.6x2.4142.81.52 (2.1 / 1.0)40
ZendureA41200026046.17.2x10.8x2.4186.61.52 (2.1 / 1.0)55
TeckNetiEP 390900019346.66.4x10.2x2.3152.81.52 (2.1 /1.0)25
MophiePowerstation Plus1200025347.47.1x10.8x2.8214.7Not stated2 (2.4 / ?)149
MophiePowerstation XL1200031138.67.1x11.4x2.3186.2Not stated2 (? / ?)130
XiaomiPower Bank1040025440.99.05x7.7x2.2150.52.01 (2.1)50
IbattzMojo Battstation Tough1200035034.37.2x11.0x2.1166.31.02 (2.1 / 1.0)70
RavPowerIcona1000023542.67.0x13.5x1.4132.31.02 (2.0 / 1.0)34
RavPowerDeluxe840018146.36.4x10.0x2.0128.01.02 (2.0 / 1.0)20
RavPowerSavior900023738.07.0x11.3x2.8221.5Built-in charger2 (2.4 / 1.0)50
RavPowerElement 1040022845.67.0x11.2x2.1164.61.02 (2.0 / 1.0)25
Patriot FuelFuel+900018947.69.4x11.4x2.5267.91.52 (2/5 / 1.0)50
Go CrankDash900018148.19.8x6.4x2.2138.02.02 (2.1 / 1.0)40

Some comments on individual products.

The EasyAcc Transformer 9000 looks like a good product but it’s availability is currently limited-to-none. I used the previous model EasyAcc 9000 (the U-bright) on my AT hike in 2014 and it worked well.

The Unu Superpak 10000 claims boldly to be the “the world’s smallest 10,000mAh battery” which is completely wrong since the Anker E3 is at least 10% smaller.

The Anker range all have a “shake to wake” feature which may make them unsuitable for backpacking. In fact you should be wary of any battery that is too easy to turn on, such as with a power button that sticks out.

iBattz only offer 1a input across their whole range. While one could put up with that in a battery under 8000mAh it  would be hard to deal with  with the quoted recharge time of “~16 hours” for the 20,400 unit! Hopefully they will catch up with the times soon.

Zendure products originated in a Kickstarter project and now (Jan 2015) appear to be hard to obtain. The specs on the 12000 are significantly better in terms of m/g than the 9000 which means at least one of them is likely to be inaccurate (I’d expect the 12000 to weigh more than the quoted 260g).

TeckNet are UK-based but their products are available on the U.S. Amazon. Their website lists over-optimistic weights so the ones included in the table are from a different source. While the 9000 product may be advertised as having a 1.0 amp input they confirmed to me in writing that it does in fact boast a better 1.5a rating. They list a 10,000 capacity battery on Amazon but not their own website, often an indication of an older product about to be discontinued so I omitted it from this review. It’s quoted weight of 210g and m/g of 47.6 would make it worth considering though if you see it available.

RavPower have a wide range of batteries worth checking out. The 9000 model included here may look bulky and heavy but it actually has an integrated wall charger (US prongs) and your choice of an integrated 60cm Apple Lightning cable or MicroUSB cable) already built in so the true story is quite good if you just want an all-in-one unit.

NewTrent are well-known and their batteries are often mentioned by hikers. But they have not been producing batteries since early 2014.

The Mophie Powerstation 12000 was not actually available for sale at the time this went to press but the specs quoted are from their website. The next capacity down is only 7000 so I had to focus on the 12000. It comes with a choice of Apple Lightning or Micro-USB cable built-in, as is the USB charger cable for charging the battery itself. Regarding input amps on all Mophie products listed: there is no information. Regarding outputs there is only a claim that the Lightning cable provides 2.4amps, there is no information on the free USB port or the Micro-USB cable version. I would guess a classic 2.0 / 1.0 but it’s just a guess. Clearly their target market is not technically discerning. The first sentence on the XL product page is, “The powerstation XL is the longest lasting universal battery available today.” which is erroneous and misleading. Also, the whole range costs so much more than all the competing products on the market it’s quite remarkable.

Patriot Fuel+ 9000 is a competitive unit with a 2.5a output and charge-through capability. But three factors make it an also-ran: price, size and lack of LED torch. You can make your own mind up about price and the importance of a torch but the size is rather unfortunate – 70% larger (or worse) than competing units. This makes it a ‘miss’ for me.

Go Crank’s Dash was suggested by reader Ivo in late Feb 2015. I have included it in the table and it appears to have excellent specs in a compact unit. Note that I took a reviewer’s stated weight of 6.6oz rather than the list weight of 6.3oz (m/g = 50) as I always do since those tend to be more reliable, so it might be slightly lighter than I have listed. The Dash unit supports charge-through (in some way, no details are given) and has a nice rubber finish. However there are a number of ‘caveat emptor’ signs here. The company was only registered in late July 2014 (in California), there is no manual or technical details available online, the product can only be purchased through Amazon but doesn’t ship internationally (usually enough for it to be excluded from this list) and there are only 23 reviews. All those reviews are from August to November 2014 (so no reviews at all in the last 3.5 months) when the product launched and most are from the recipients of reviewer samples, not actual purchasers.

 

Best Battery in the 8000-9000 class

Winner

TeckNet iep390 9000 batteryTeckNet iEP 390, 9000mAh. Chosen because it is the most weight-efficient product in its class with a best-in-class m/g rating of 46.6 it holds its own with all but the best of the units from the bigger class. But it doesn’t achieve this by cutting any obvious corners and includes a very respectable 1.5 amp input to get the battery charged quickly, and an LED flashlight for occasional use. Standard dual outputs and a reasonable $25/£17 price on Amazon make this easy to recommend.

Runner-Up

RavPower 8400 batteryRavPower Deluxe 8400. Sure, it only has a 1 amp input but at this capacity it can be forgiven. The 181g weight gives it a great juice-per-gram rating and it still includes a LED light. It’s best feature though is its size – smaller than some 6000 units on the market.

Honorable Mention

Powergen Ultragen 9000Powergen Ultragen 9000. A decent 1.5 amp input for this capacity makes for fast recharging and it has a unique 3 outputs – a normal full-size USB port with 0.6 amps,  a second port that outputs up to 2 amps shared with an integrated Micro-USB cable. In other words those two outputs support two devices charging at 1 amp each or one at 2 amp, or any combination  in-between. For Android phone users, or anyone with a device that uses Micro-USB,  the built-in cable means they don’t need an extra cable, just this battery. But the unit still has a class-leading weight and even includes an LED flashlight. Finally, the $20 price lets you try without risk. Apart from a slight bulkiness, the only weakness is the paltry 0.6a on one of the ports,  adequate for small MP3 players but otherwise will provide a slower charge for devices like phone or GPS units that usually expect 1 amp.

 

Best Battery in the 10000-12000 class

Winner

Powergen Vitalgen 12000Powergen Vitalgen 12000. A full 2.0 amp input is appreciated at this level and it packs in a lot of juice into a light product, with an excellent 48.7 m/g. It holds its own in the size category. It stands out in providing 3 outputs (one of which always provides 2 amp, the other two of which share a further 2 amps – e.g. two devices drawing 1 amp each) meaning it offers more flexibility than the other products – conceivably you could plug in your Kindle, smartphone and music player all at the same time, and the 12000 mAh capacity means that is not a crazy scenario. Finally a LED torch provides a useful option. At just $40 this a bargain to boot.

Runner-Up

Anker Astro E3Anker Astro 2nd Gen E3. A 10000 unit, but the 13000 E4 unit is slightly more efficient if you want an even larger unit and Anker have other products worth checking out though different ranges have different feature sets (the E3 is the best weight-wise). It was a close run thing between the Zendure A4 (slightly better on paper but with question marks over its current availability) and the Anker. The stellar reputation of the Anker brand, wide availability, 18 month warranty and full 2.0 amp input swayed it.  It’s also relatively petite, just a shame it doesn’t include a torch.

 

7 thoughts on “External Batteries – 2015 Market Review

  1. I wish you tested the efficiency for the ones you had on hand.
    You can buy a cheap $5 OLED screen USB amp meter that will measure how much power passed by at 5V.

    My Anker Astro E1 5200 mAh only has around 60% efficiency which I found to be a surprise for a well regarded brand. The build quality and everything else is very good, but with such low efficiency it’s kind of a bummer. This will charge my Galaxy S7 Edge (3600 mAh) one full charge and then have 621mAh@3.7V left.

    1. All external batteries, as far as I know, use battery cells rated at 3.7v. Since the product has to provide current at 5v there will always be a 35% loss due to this voltage transformation. After that the individual product’s efficiency can be measured. 60% is therefore par for the course.

  2. Sparky! Just went through this again as I purchased a new Google Pixel phone. If you ever do that wall charger post/review, I would be interested. I’ve found the Anker and Powergen ones you noted in the older post on the topic, but I wonder what has changed. Anyways, best of luck on your PCT prep. I hope you have a wonderful fall/winter, and can’t wait to hear about your adventures on the PCT!

    Best Regards,
    -Paul

    1. Hey Paul. For batteries right now it seems Ravpower for general purpose (i.e. Not for the newer Android fast-charge methods) or Anker would cover most people’s bases. I’m going to use a 6700 Ravpower on the PCT plus a second in the Sierras for safety. For wall chargers my Aukey dual USB as used on the AT is tiny and just perfect.

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