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Posted on July 16th, 2014 by Darien Graham-Smith

Smartphone battery packs: can a USB power pack beat the festival battery blues?

20140629_152204Until recently, there wasn’t much point taking your smartphone to a summer festival. With tens of thousands of people converging in the middle of the countryside, it was impossible to get a signal, and your battery was likely to expire on the first day anyway.

But things are changing. Coverage has improved markedly in recent years, and event organisers are starting to embrace mobile technology with official festival apps and onsite charging facilities – a more popular attraction than many of the bands, judging by the size of the queues.

Lowering the bar

PowerbarFor this year’s Glastonbury Festival, EE came up with a clever little thing called the Festival Power Bar – not a snack, but a baton-shaped battery costing £20 that could be easily carried around and used to recharge your phone over a regular USB cable as needed. Fully discharged bars could be swapped for freshly-charged ones at the EE tent, so you could keep on trucking without too much hanging around.

Predictably, the bars sold out long before the festival opened. Unfortunately, I suspect those who invested found themselves traipsing back to the exchange point rather more often than they’d anticipated.

That’s because the rated capacity of a Power Bar is a rather weedy 2,000mAh. According to EE, this is enough for “five hours of charge”, whatever that may mean. In practice, it doesn’t take a senior wrangler to realise that this isn’t going to fully replenish the 2,600mAh battery of a Samsung Galaxy S4.

What might surprise you is the scale of the shortfall. When you discharge one battery to charge another, a lot of energy is lost in the conversion. How much charge you lose will depend on all kinds of factors, but a 30% drop between battery pack and phone is entirely plausible. In other words, using a mobile power pack is tremendously wasteful of energy  and it means that a moderate smartphone user could charge up from a Festival Power Bar at the start of the day and still find themselves on emergency rations before the Kaiser Chiefs finally get around to playing “I Predict A Riot”.

High-capacity power packs

Of course, larger power packs are available. A friend of mine braved this year’s Glastonbury with a Proporta USB TurboCharger 7000 – a compact little battery roughly the size of a portable hard disk. Although rated at three and a half times the charge capacity of the EE Power Bar, this still only managed to charge her HTC One twice before it was completely drained. Happily, since the power pack itself charges by USB, she was able to refuel it at the recharge tent on the Saturday, and thus get through the festival.

Festival-smallMy partner and I meanwhile had invested in something meatier: the Anker 20,000mAh Astro Pro2 charger. This wasn’t actually our first choice, but for some reason the 22,000mAh pack we originally ordered wouldn’t charge my Galaxy S4: I gather that some devices are finicky about their power requirements, and won’t charge if the voltage and current aren’t exactly as expected.

The Anker is a serious piece of kit: it’s the size of a novel, it weighs a chunky 510g and it set us back fifty quid. But it charges all our devices, and also boasts a natty display showing exactly how much charge remains. We each got two charges out of it before it died – a more impressive feat than it may sound, since I’m still using my high-capacity 5,200mAh battery.

On account of its huge capacity, the Anker power pack charges from the mains rather than via USB, so at first we feared we wouldn’t be able to recharge it at the tent. Thankfully, a nice man found us a spare three-pin socket tucked away in the corner, enabling us to refuel the Anker in a matter of hours, and stay in touch for the rest of the festival.

Power to the people

We were disappointed that our power packs didn’t make it through the entirety of Glastonbury, but they did allow us to minimise our time spent queuing at the recharge tent. If you’re going away for a shorter spell, a portable battery may be just what’s needed. It might also be a sensible thing to keep in a car in case of emergency – although official advice seems quite variable as to how long a lithium-ion battery should be left unused in a charged state.

What can be said for sure is that until battery technology develops a bit further – or until really huge battery packs become the norm – you’ll still need to use your phone sparingly at festivals. That, or resign yourself to queuing up for a periodic juice boost.

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Posted in: Hardware, Real World Computing


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24 Responses to “ Smartphone battery packs: can a USB power pack beat the festival battery blues? ”

  1. Alex Says:
    July 16th, 2014 at 7:39 pm

    I have just invested in the 14000mah RavPower battery pack. On it’s first charge it fully recharged my Note 2 (3200mah) from 9% to 100% twice and also fully charged my daughters Galaxy Tab 2 7″ pad (4000mah) from 8% to 100% and there was still enough power left to add another 10% to the Note 2. It’s a nice bit of kit.

  2. Tim Says:
    July 16th, 2014 at 9:58 pm

    I think Darien needs a new perspective on life. Failing that a Nokia 610 will happily last a full weekend without a recharge if you switch it into flight mode overnight.

  3. colin Says:
    July 16th, 2014 at 10:51 pm

    Spent 3 days at Silverstone for GP and my Nokia 1520 coped with no problems without any need of switching to flight mode. I realy couldn’t be doing with having to worry about charging a phone every day.

  4. Gavin Moorhouse Says:
    July 17th, 2014 at 6:45 am

    Have to say when I go to festivals / camping holidays my phone is normally dumped or if does come with me, it remains turned off for emergency use only. Everyone needs a break.

  5. james Says:
    July 17th, 2014 at 8:48 am

    I’d be worried about a good phone being lost or stolen. Something like the nokia 100 would solve the battery life and lost/stolen concerns.

  6. Lise Says:
    July 17th, 2014 at 9:08 am

    Until recently I might have agreed with the pro-Nokia crowd, but the fact is that in recent years festivals have actively encouraged the use of apps (the offical Glastonbury app got us usefully around the site on time to see acts we definitely didn’t want to miss, leaving us plenty of opportunity to wander at leisure in betweeen)- this weekend’s Latitude has a similar app to keep festival-goers up to date with event info.

    While it’s not necessary to photograph or video live events to enjoy them, I am very fond of the video I shot of Kasabian using my iPhone 5S and my photos of Dolly Parton, which I was able to share immediately on Twitter. Twitter buzz is itself now as much a part of the festival experience as cider and wellies – again, you could get through a weekend without checking social media if you wanted, but it added an extra dimension for us to see other people’s reactions to the acts we’d attended (or missed).

    Of the thousands of people we saw using phones at Glastonbury, I believe not one was using a Nokia or similar device. It’s wise to take precautions with your devices when you’re in a crowd of strangers, of course (mine stayed zipped in an inside pocket when I wasn’t actively using it), but there’s no more reason to fear for your phone’s safety at a festival than there is when you’re travelling on the Underground. Smartphones didn’t replace the festival experience for us, but in my view they did add to it and provided us with some happy mementos.

  7. Rob Says:
    July 17th, 2014 at 9:11 am

    I have one of these. It can charge any USB device and you can swap out the AA batteries. 4xAA = 8000mah, so for a few quid spent on batteries (charge them before you leave for the festival) you can have a whole weekend of power.

    Plus, it can also charge batteries!

  8. JohnAHind Says:
    July 17th, 2014 at 9:19 am

    “sensible thing to keep in a car in case of emergency”
    If you have a car, you can surely charge from the cigarette lighter socket?

  9. Chris Says:
    July 17th, 2014 at 9:30 am

    I don’t have a problem when I go camping as I always have my 110 amp hour battery and 240v 1 KW inverter to hand.

  10. David Says:
    July 17th, 2014 at 10:24 am

    Anyone any thoughts on portable Solar Power? Both for the UK, and abroad.

  11. JohnAHind Says:
    July 17th, 2014 at 11:55 am

    At risk of attracting further scorn from Ms Kobie, can I again remind everybody that the correct units for energy storage capacity are Watt Hours, not thousands of milliamp Hours (or even Ah).

    Amp hours are meaningless unless you specify the voltage. Milliamp hours quoted are probably the total capacity of the cells within the unit at the cell voltage of around 3v (for Lithium Ion) so the actual power delivered at 5v will be substantially less. (@Rob: the voltage of an alkaline AA cell is about half that of a Lithium Ion cell, so the capacity is about half at the same Amp Hour rating – this is why we should be using Wh!)

    Manufacturers (and reviewers) should state capacity in watt hours at the rated output voltage after conversion losses.

  12. Graham Allen Says:
    July 17th, 2014 at 4:30 pm

    Alternatively leave your phone with the property lock-ups for a recharge… for the cost of a donation.

  13. Charlie Says:
    July 17th, 2014 at 4:34 pm

    @JohnAHind, the correct unit for battery capacity is the Ampere-hour (from Wikipedia), but you are correct that it does not represent a measure of energy. In a past life, I have used battery capacity (in a simululated battery) as part of a real-time flight simulation. What is more baffling is why does it always get expressed in mAh rather than Ah when the value exceeds 1000

  14. TV John Says:
    July 18th, 2014 at 8:56 am

    David: Yes, I’ve used a 13W briefcase solar panel before. This was a few years back but it comfortably kept my HTC HD2 charged for the week of a festival. You have to be confident about leaving your phone unguarded in your tent, of course.

  15. colin Says:
    July 18th, 2014 at 1:31 pm

    Don’t be silly Charlie, why would I want a 1520 with 3.4Thingamajigs, when I can have one with 3400thingamajigs. ;-)

  16. JohnAHind Says:
    July 22nd, 2014 at 12:22 pm

    My Galaxy Note has a Li-ion battery rated at 3.7V, 9.25Wh (top marks Samsung) but the marketeers call this 2500mAh. So it is clear that they are measuring at the 3.7V cell voltage not the 5V USB voltage.

    Stating ONLY Ah is meaningless: you can state Ah and V, or more simply you can just multiply them together and state Wh.

    The important thing is that a “2000mAh” 5V auxiliary power pack will probably not, as the purchaser might reasonably expect, deliver 2A at 5V for 1 Hour.

  17. Charlie Says:
    July 23rd, 2014 at 9:47 pm

    The point of battery capacity in Ah is that it gives a measure of how long your battery charge will last. The voltage value is not part of this equation and is therefore not important, only the current drain is used in the calculation along with time.

  18. JohnAHind Says:
    July 25th, 2014 at 5:33 pm

    @Charlie – Pah! How does it give a measure of how long your battery will last unless you have a measure of the current being drawn from the battery?
    The point is that these days voltages are routinely and efficiently boosted or bucked to different levels (in this case from 3.7v to 5v). What we need is to be able to compare the energy capacity of two different devices. See the example above where someone thought a 1Ah Li-Ion battery had the same capacity as a 1Ah Alkaline battery. That confusion does not happen if you use the proper units: the Li-On battery is 3.7Wh while the Alkaline is only 1.5Wh.

  19. Charlie Says:
    July 27th, 2014 at 4:31 pm

    @JohnAHind, please re-read post 17 carefully followed by post 18. The latter is precisely my point; battery capacity in Ah is a measure of the current being drawn from the battery (which is exactly what post 17 says). Please don’t be afraid to do further independent reasearch into what battery capacity actually is; you will then find that my statements have been 100% accurate.

  20. IanL Says:
    August 5th, 2014 at 8:09 am

    I know I’m a bit late to this discussion, but I’d like to add that my Galaxy SIII and a no-brand but similar smartphone I have will both happily last five days in phone-standby with occasional use as long as all the other radios (bluetooth, gps, wifi, mobile data) are only turned on when I actually need them.

  21. Chriskno Says:
    August 6th, 2014 at 7:30 pm

    Have a look at A brilliant solar powered light and usb charger that I use all the time with my phone. And when you buy it helps fund one for places like Haiti earthquake victims, Syria refugees. I have no attachment to them other than I contributed to their Kickstarter launch. By the way, I live in Cumbria and get enough sun up here!

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