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Portable Power Question

I go camping a lot and sometimes get worried about a dead battery (had it happen a few times).
I have seen these 5600mah to 10,000mah power banks on Amazon pretty cheap,looking at a 5600mah PowerBank brand for 12.99 + 4.99 shipping, 5600mah UniCharge for 19.99 + 4.84 shipping or 10,000 RavPower for 19.99 and free shipping.
Any ideas on these?
If the PowerBank is OK, might get 2 of them.

For a DIY, I have a few 7.4v and one 11.1v 5000mah Lithiums for RC car, I thought about getting a USB car charger and hooking it up to one one them and using it. I also have a couple NiMH batteries also.
Any ideas on whether that will work or a bad idea?
 

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#1 Stuartlittle, Aug 6, 2013
I've seen portable packs that hold up to 15, ,000mah but are more expensive of course . I've never heard of rave power or uni power so Idk about the quality but they seem a little TOO cheap. As for the diy I thought you could only charge a phone with 5v and anything more would fry it.
 
#2 Zolo185, Aug 6, 2013
Good review of a Anker 12,000mAh powerbank ...
http://androidforums.com/showthread.php?p=6019994

Harry
 
#3 Harry2, Aug 6, 2013
a car cigarette lighter is 12 volt, the car charger output is 5 volt @ .5mah.
Maybe I could look something up on youtube.

Those power banks were found on Amazon.
 
#4 Stuartlittle, Aug 6, 2013
You should look at the output of the powerbanks before looking at mah. A 12000mah powerbank with an output of 3.7V is just roughly 7000mah for a phone, give or take.
 
#5 chanchan05, Aug 6, 2013
Yeah, an efficiency of 60-70% is my experience too.

The cause of this efficiency's decrease:
Power bank's battery: 3.7V ->
transformed to power banks's output: 5V ->
connected to phone's input: 5V ->
transformed to phone's battery: 3.7V

Harry
 
#6 Harry2, Aug 7, 2013
A good reason to choose a quality power bank is the tolerance with that batteries are labeled by their manifacturers. As far as I know tolerances of the battery's capacity down to -25% are licit.
So, a power bank labeled as 12,000mAh might have just 9,000mAh.

You won't find such a "-25%" battery in quality power banks ... but you've a big chance to find such a battery in cheepy's ;)

Harry
 
#7 Harry2, Aug 7, 2013
I just received the Uhuru! 5600mAh portable charger made by Gorilla Gadgets. I ordered it from Amazon and I am very impressed with the quality of the charger. I haven't had a chance to really put it to the test, but I have confidence it will do the job.

Amazon.com: [180-Day Money Back] Gorilla Gadgets Uhuru! 5600mAh External Portable Battery Pack Charger with built-in Flashlight - Coconut White Edition - Upgraded from 5200mAh capacity - Compatible with Apple: iPad mini, iPhone 5, iPad 4 (Lightning C
 
#8 star444, Aug 7, 2013
I always have the same problem with camping. The best solution I found is to keep your mobile phone OFF, dude you are on a vacation camp. You can live without it. and in case of emergency you can turn it on and call :)
 
#9 mobilephones13, Aug 7, 2013
So I went out and bought one, I got a Sound Logic XT from Tiger Direct, since it's just down the road from me I decided to buy it in store.
It's a 5600mah, while it does work, it charges very slow, my Event was at 42% and it has been on the charger for about 2.5 hours and is at 95%.

Is this normal for these chargers?
Would an Anker be faster?
 
#10 Stuartlittle, Aug 9, 2013
Yes, it would ... but only if I use the USB cable which came with my Anker 5,600mAh.

The reason is that most phones/tablets need to "see" modified data lines before they allow be rapidly charged with high amperage.
Your wall charger which came with your phone should have this modification too.
Some info ... Wikipedia: Jumpered data pins on USB chargers

Back to Anker. Its USB cable has adapters for all kind of phones (Apple too).
And the adapter for Android phones has this modified data pins in its microUSB connector :)

Harry
 
#11 Harry2, Aug 10, 2013
I used the cord that came with my Kyocera Event, next time I'll try using the one that came with the unit and see how it works.
I plugged it back in this morning using the included cable, a few minutes later it was shut off, so I guess it charged it to 100% and then the charger shut off. After that one charge it's now down to 2 bars.
 
#12 Stuartlittle, Aug 10, 2013
Seems it can charge twice.
 
#13 vosca, Aug 19, 2013
As Harry2 pointed out, check out my external battery reviews: http://androidforums.com/samsung-galaxy-note-2/708384-twister-reviews-note-2-accessories.html

I'm a bit biased and have soft spot for Anker because those products never failed me. Their new 2nd gen line of chargers stepped up to 80% efficiency and some cool new controls.
 
#14 twister6, Aug 26, 2013