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This is a review of Anker Astro E7 25600 mAh external battery. http://www.amazon.com/Ultra-High-Capacity-25600mAh-External-Technology/dp/B00M3073L4/

About a week ago we were expecting a big snow storm. Thank God it turned out to be nothing, but in preparation I went through my usual routine of getting extra food and water, getting extra gasoline for our generator, and.... making sure all my Anker batteries are charged up! I often talk about external batteries as a boost source on the go when you want to have something small and pocket friendly. But if you want to be prepared for any emergency or planning to be away from a power source for days - you want to have a battery with a big enough capacity, and that's what 2nd gen Astro E7 delivers with its enormous 25600 mAh. Here is more about it.

After reviewing so many different Anker batteries, I'm already used to their environmentally friendly packaging and typical accessories of a high quality usb to micro-usb cable and storage pouch. But it's always a surprise to see how big the battery turns out to be based on the advertised capacity. You have to realize that increased capacity comes at a price of increased size and additional weight. It's a simple math - higher capacity means more internal battery cells. That is why I never trust some of the budget ebay and other retailers small battery bricks claiming 20k mAh in a footprint of 10k battery. Out of the box, you will definitely feel the weight of E7 at almost 16oz (450g), but it's still manageable thanks to its slick rectangular shape with rounded edges which is easy to handle. With a dimensions of 166 × 80 × 22mm (6.5 × 3.1 × 0.9in) it can actually slip into your front pocket or cargo pants side pocket without a problem, though it will be noticeable. The whole intent of this battery is not to be a small portable back up charger but rather a portable charging power station to give your phones and tablets a boost with up to10 combined charges.

The design is similar to their other 2nd gen E-models, just scaled up in size. You still get a slick piano finish plastic body, very sturdy, no flex. Also a power button on the side to turn the battery on/off, though I found it starts charging automatically as soon as it detects attached device. Another function of power button is to turn built-in white LED by holding and pressing this button. LED functionality is a welcome bonus, especially in emergency situation to use as a portable flashlight or to lit up usb ports so you can connect the cable in the dark. The top of the battery has 4 LEDs to indicate remaining power or to display charging power. These indicate 25% per LED, not as accurate as a regular Astro line with 10-led indicators, but for bulk charging this should be sufficient. I also prefer led indicators over some other batteries that use LCD display which drains the battery. And speaking for that, I can confirm that all of my 2nd gen Anker batteries hold the charge for multiple months when not in use.

E7 model comes with one micro-usb input charging port and 3 full size usb power output ports, each equipped with PowerIQ feature that automatically adjusts current supply per attached device requirement. So if you have an old Android phone, it will source only 1A, while newer phones will get 2A, and your latest iPad will be charging at full 2.4A. Just have to keep in mind that a total combined current can't exceed 4A. Another very important feature is 2A charging input. With a capacity of 25,600 mAh it will take you over a day to charge this battery from empty using a typical 1A charger. Here with 2A wall charger you can juice it up to 100% in approximately 12-13 hours. Also, it's very important to keep in mind that with any battery you have to take into account the convergence efficiency since you are going between 3.7V cells and 5V usb interface. Anker converters are usually very efficient and deliver only 10-12% drop, bringing it closer to 90% efficiency. In comparison, a lot of other batteries are struggling around 80%. With Anker E7 battery you can get about 23,000 mAh of the actual charging capacity.

Overall, I'm always impressed with power products from Anker and consider their external batteries to be among the best. You don't have to take my word for it or to tell me that I'm biased, just search our community for all the positive feedback or look on Amazon where it's #1 best seller in every category with thousands of 5-star reviews. The combination of top quality LG battery cells, durable design, super fast input charging without a need to use proprietary connectors (just a standard micro-usb), bonus of LED light, high efficiency and huge storage capacity, and their 18-months warranty and excellent support - makes this battery my top recommendation, despite a price tag of $80 (just factor in combined cost of smaller capacity batteries).

Here are the pictures.

E7 next to E4