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Anker Astro Slim2 4500mAh Ultra-Slim Portable Charger External Battery Power Bank for Samsung Galaxy S5, S4, S3, iPhone 6, 5S, 5C, 5, 4S, iPad Air, mini, Note 3, 4, HTC One, One 2 (M8), Motorola Droid, MOTO X, LG Optimus and most other USB-charged devices

4.2 out of 5 stars 780 customer reviews
| 73 answered questions

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Product Features

  • Size (LWH): 4.96 inches, 2.52 inches, 0.39 inches
  • Weight: 4 ounces
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Product Description

Mobile Battery Brand · Anker proud of the United States, the United Kingdom, Germany, etc., the 200 000 or more total sales (anchor). Clear strict quality standards FCC, CE, RoHS, etc., of the United States and Europe. Slim design so as to be superimposed on smart phone, can call or browsing while charging. Equipped with a dual-port, charging at full speed to the two devices is possible. Using a micro chip and battery cell with high quality, can be used repeatedly for more than 500 times. Since the integrated Micro USB cable, if you use, the cable unnecessary separately Android terminal. When charging, please use the supplied cable terminal of Apple itself to Apple terminal. Please note: 18 months warranty for this product is only applicable if Amazon.co.jp or AnkerDirect has become a distributor.

Product Information

Product Dimensions 5 x 2.5 x 0.4 inches
Item Weight 4 ounces
Shipping Weight 7 ounces
Item model number AK-79ANS4552-BA
Customer Reviews
4.2 out of 5 stars 780 customer reviews

4.2 out of 5 stars
Best Sellers Rank #115,428 in Cell Phones & Accessories (See Top 100 in Cell Phones & Accessories)
#1,651 in Cell Phones & Accessories > Cell Phone Accessories > Batteries & Battery Packs > Portable Power Banks
#1,714 in Electronics > Portable Audio & Video > MP3 & MP4 Player Accessories > Batteries & Battery Packs
#115,114 in Electronics > Cell Phones & Accessories

Warranty & Support

Product Warranty: For warranty information about this product, please click here


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Customer Questions & Answers

Customer Reviews

Top Customer Reviews

Verified Purchase
This power bank is small, light, manageable, well designed, and well priced.

That being said my phone has an 1800mAh battery. Being that this battery is rated at 4500mAh, even after considering power lost to heat, and internal processes the bank has built in, it seemed reasonable for me to expect 2 charges. Sadly the Astro Slim2 delivered just a little over one.

Considering the quality, and thoughtful design, if you often find yourself out and about and away from a charger in your car or at home, this unit is still worth the money, and I'd still recommend it.


Anker responded to the negetive aspects of my review in a ridiculously fast manor, offering a replacement and seeming incredibly helpful, but I don't believe the item to be defective, still be of quite good quality, and am happy to have it. And now you can be sure the customer quality is impeccable. Again not a bad product if it's for you, but I can highly recommend Anker products in general, because they stand behind their products, and try to make sure their customers are happy.

(Update #2)

Anker mailed me an unsolicited replacement just in case original unit was under-performing. After a few discharges I've come to the conclusion that the new unit is slightly outperforming the old. I am currently getting about one and one half charges, and suspect I may get a full two charges, if I were to completely shut my phone down during charging, but for what are probably fairly obvious reasons this isn't really practical. As stated earlier, the company has quality, affordable products with unbelievable customer service. If you're on the fence about purchasing a product the company offers, you should take their willingness to go above and beyond into consideration.
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Length: 7:55 Mins
This is a beautiful product for anyone who travels or works long days. You can charge your smart phone while on the bus, train, and plane or in a meeting without looking for one of those hard to find wall plugs. This powerful battery pack can charge your smart phone multiple times or extend the use of your smart tablet. (Please see the details listed below in my test results)

It is beautifully designed, extremely thin, small and portable. It uses Grade A power cells which will provide years of recharging capability, up to 500 plus times. The battery pack has the power storage of 4500 mAh. It has a standard USB port and a built in Micro USB cable that can both output 5VDC at 1 AMP each, simultaneously. It can charge two devices at the same time. My testing reveals that this battery pack is powerful and effective with the capability of outputting 3700 mAh of its charging capacity which is 82.2 percent of its rated capacity which is an excellent result.

What I like is that the unit is priced well and it is so small and portable but can really carry a lot of power. It easily fits into your purse, briefcase or pocket. Since it is only 0.42 inches thick it can easily slip into a jacket pocket for easy access. You could recharge most smart phones from 2 to 3 times with this power cell. The battery pack is about the same size as an iPhone 4. It weighs in at 4 1/8 ounces and it has a matte finish that helps you to grip it and it does not show fingerprints. I have included a video of this review and I hope it is helpful to you.
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I think Anker finally hit the sweet spot in portable USB batteries with the Astro Slim2, and I've used my share of them. Of course, as an ultra-slim battery with just 4500mAh, this isn't going to charge your tablet or jump start your car. What it will do, though, is give your precious cellphone that extra kick when you're just about to beat that Angry Bird level and your battery is down to its last breath. It will do it in style, too.

The Anker Slim2 is about the size of your typical new-gen cellphone; it is nearly identical in size and thickness to my Google LG Nexus 4. This means that it is just the perfect size to slip into the inside pocket of a suit or jean pocket. I can't mention how many times I've had to leave my other portable batteries behind because they were just too bulky or awkwardly shaped, rendering them completely useless when I needed them most. There's no need for a second thought with the Slim2; just slip it into a pocket and go. Forgot to bring a cable? No sweat; IT COMES WITH A BUILT-IN CABLE.

Did I mention that it comes with a built-in cable?!

Sorry for those in the proprietary cable camp (I'm looking at your, Apple), the built-in cable is Micro-USB only. Which means that, oh I don't know, it will work with JUST ABOUT ANY Android cellphone in the market. When not in use, the cable tucks neatly into the battery charging port. If your device doesn't have a Micro-USB charging port, Anker showed some love by including a USB output port as well so you can BYOC (Bring-Your-Own-Cable). Anker threw in a Mini-USB and a 30-pin iPhone adapter too, just for kicks. Furthermore, the Slim2 has a 4-LED display that tells you how much battery is left so you're never left wondering.

This all sounds amazing, so you might be wondering why the 4-star.
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