I am a huge supporter of having external battery packs when traveling with any sort of battery-operated device you may depend upon for navigation or help. Right now, receive 50% off the GreatShield Power Tank 10400mAh High Capacity External Battery Pack Power Bank with 3.1A max usb output. Originally $79.99, the GreatShield external battery is just $39.95 right now. It is among the cheapest battery packs over 10,000mAh that you can find on the market right now.
I own two external battery packs. One lives at my husband's work so he can charge his phone without having to transport his phone charger between work and home. That would inevitably result in him leaving it at either place and then having a dead phone. As the external battery charges over USB, he can just recharge the battery via his work computer.
The larger battery I have is for travel. My iPhone's battery is not dependable and it can jump from 58% down to 12% in a heartbeat. In addition, when I had an iPad as well, I could charge both at the same time with the dual charging system. The GreatShield external battery features the same system. One port outputs 2.1A and the other port outputs 1A. The larger output is perfect for charging tablets while the smaller output will handle your smartphone just fine.
A 10,400mAh external battery can charge an iPhone several times over and give an iPad about one and a half charges if I remember my capacities correctly. They are so incredibly useful, not just for traveling but around the house as well. My house outlets are in the most inconvenient places, so I often charge my phone off the battery pack so I can still use it while charging.
There are a couple other deals on external batteries I wanted to point out in case this one does not meet your needs. The FosPower POWERACTIVE 9000mAh (WATER/SHOCK/DUST PROOF) Rugged Heavy Duty Power Bank is on sale for $39.99, originally $69.99. This is the only external battery I would feel safe giving to my Dad, as anything electronic needs to be heavy duty.
The Anker® 2nd Gen Astro Pro2 20000mAh Multi-Voltage (5V 9V 12V) 4-Port Portable Power Bank Pack External Battery is also an amazing deal at only $89.99, originally $119.99. With this size of battery, you can charge an iPhone 10 times before recharging.
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