Your Position: Home > External Batteries > Astro Slim >

Anker Astro Slim3 6000mAh Portable External Battery

Anker Astro Slim3 6000mAh Portable External Battery

Charger- 40W 5-port desktop charger

Product Description

Mobile power that stacks up - literally.

Slimmer and stronger.

At 0.47in, Anker's Astro Slim3 comes with enough power for 3 or more charges to most smartphones in a compact, easy-to-grip case. Sized especially to stack behind your 4.7in smartphone for uninterrupted phone use while charging. An LED column unobtrusively lets you know just how much juice is left.

Say goodbye to knots.

Who doesn't hate tangled cables? With an intuitively-sized micro USB cord for Android, the Slim3 allows you to carry your power all-in-one. Using an iPhone? Plug into the USB port and charge up via your OEM cable. Free yourself from cords and get back to what's most important: life.

No expense to speed.

What's better than a high-capacity battery that slides into your pocket on-the-go? One capable of simultaneous, full-speed charges. Both ports supply 1A of power with complete safety to your phones, so you can power up in no time and make the most of your day.

For optimal use

- To ensure complete safety and best performance, we strongly recommend using your device’s original cable, a third-party certified cable (such as MFI) or our included cable.
- For simultaneous, max-speed charging of your Astro and other devices, check out Anker's new line of 18W / 3.6A car and home adapters.
- Compatible with all Apple and Android smartphones, tablets and other USB-charged devices. The iPod nano, Asus tablets (not include the Nexus 7), the LG G2 and some GPS and Bluetooth devices are not supported.

Popular Compatible Models

Apple: iPhone 5S, 5C, 5, 4S, 4, 3GS / iPad, iPad 2, iPad 3, iPad 4, iPad mini / iPod (Apple adapters not included)
HTC: One Max, One, One X, S, V / Sensation, Sensation XE XL / EVO 4G / Radar 4G / Inspire 4G / Vivid 4G / Wildfire S / ThunderBolt / Incredible 2 S / Rezound / Desire X, C, V, HD, S, Z
Samsung: Galaxy S4 / S4 mini / Galaxy S3 / Galaxy Note 3 / Galaxy Note 2 / Galaxy S2 I9100 / Galaxy S I9000 / Verizon Galaxy S3 I535 / AT&T Galaxy S3 I747 / Sprint Galaxy S3 L710 / T-Mobile Galaxy S3 T999 / T-Mobile Galaxy S2 T989 / AT&T Galaxy S2 I777 / AT&T Galaxy S2 Skyrocket SGH-I727 / Galaxy Nexus / Focus S / Infuse (Galaxy Note 10.1, Tab 2, Tab 7.0 not supported)
Motorola: X Phone, Droid Razr, Bionic / Atrix 2 / Triumph
LG: Nexus 4, Optimus 4X, 2X, V, S, T, 3D, 7
Nokia: Lumia 1020 920 820 900 710 800 / N8 / N9
Others: Blackberry Z10 Torch Curve 9900 9360 9320 / Sony Ericsson Xperia Arc S, Sony Xperia Z,X10 / PSP / Nook Color / MP3 MP4 MP5 / GoPro / Amazon Kindle, Kindle Fire,Nexus 7

Customer Reviews

Dominic Romeo
  • Like it, works well, built-in MicroUSB is tricky
  • No major issues, works as advertised. My minor gripe is that returning the built-in micro USB cable to the stored position can be a bit tricky. Once you get used to the angle of plugging it in, it gets easier. It is of decent build quality and was exactly what I was looking for to charge my MiFi and Nexus 5 when AC power is not available. I have not tried to use the standard USB port on the side yet.
  • 2014-04-20

Consumer Adphawkit Adphawkit Andrew
  • I love this thing - returned the 1st but 2nd is working out fine
  • I bought one of these a while back and loved it but the built-in micro-USB stopped working within a week or two of owning it. I tried it on other devices and same deal, so I returned it. I wasn't sure if it was my phone or the battery pack but it seems like it happened because, when plugged in, you can't put any tension or stress on the cable. So if you buy this - DO NOT plug it in and then put it in your pocket and walk around with it, or put it somewhere that it will shift around a lot. Your best bet is actually to plug it in when you can make sure there's no tension on the built-in cable and it's just sitting atop or below your phone (or to the side of it). On average, this thing gives me about 2 1/2 charges on my slightly extended battery. Hope that helps.
  • 2014-04-18

  • Astro slim 3 6000,ma backup
  • I don't normally leave comments, but the service and the quality product I've received from Anker are second to none. You can't loose here, the product is Leaps and bounds better than I expected.
  • 2014-04-18

  • new best friend
  • Charges fast, very portable - works great for both iphone and android devices. would give 6 stars if i could.
  • 2014-04-17

  • Great Item To Have
  • Great product to have if you are like me and always run down your phones battery and tend to not be near outlets. It will charge my phone (Nexus 5) twice. The only problem that I have with mine is that the indicator lights don't seem to be calibrated correctly. If I am charging my phone, it runs down to the last light within 20 minutes and stays there forever. I can get more than a full charge when its at the last light alone. I would just like for the lights to indicate the percentage accurately because I cant tell if its nearly dead or not. Maybe there is some way I can calibrate it myself, or maybe i need to exchange it. Other than that and the design of the charging cable interfering with some thicker cases, this is definitely a 5 star product. Hopefully they fix the few issues on the Slim4.
  • 2014-04-16
<< < 1 2 3 4 5 6 7 8 9 10 > >>

Customer FAQ

Q1.  Can I use USB cables othan than those provided with my Anker external battery?
To ensure complete safety and best performance, we strongly recommend using your device’s original cable, a third-party certified cable (such as MFI) or our included cable.
Q2.  Does it work with the new iPhone 5s, 5c?
Yes. But the Apple connector is not included. Please use your device's original cable.
Q3.  Anker external batteries' efficiency.
ALL external batteries lose power due to voltage conversion and circuit resistance.

Approximately 20% of Astro 2nd Generation external battery’s total capacity is consumed, including power lost from circuit heat and voltage conversion within the external battery (approximately 6%) and the charging cable and your device (approximately 14%). This efficiency rate is 15% higher than the industry average of 35%.

Older Astro batteries have lose approximately 30%.

According to industrial standards, all external batteries are labeled based on their raw cells capacity not efficiency. Like others, we are following this standard.
Q4.  How long will the battery lasts while not in use?
Generally, most of our external batteries' static power consumption is lower than 100uA, which will take between 3.5 and 20 years to drain the battery completely.

However, the chemicals within the li-ion battery will gradually become less active over prolonged periods without use. Most will die in 2 years of inactivity.

To extend your battery's life:
1. Charge and recharge it at least once every 3-4 months.
2. Do not over-charge or over-discharge it. It is best to keep it charged between 5%-95%.
Q5.  Can Anker external batteries be used for international travel?
Yes. Be sure the USB adapter you bring with is compatible with the voltage of the country you will be traveling to. An adapter's voltage input is usually printed on the adapter.
Q6.  Can external batteries be taken on board airplanes?
Yes, all Anker external batteries can legally and safely be taken on board airplanes. Here are the relevant requirements:

Quoted from Federal transportation security rules (Effective January 1, 2008):
Lithium ion batteries (a.k.a.: rechargeable lithium, lithium polymer, LIPO, secondary lithium).
-Passengers may carry consumer-sized lithium ion batteries [no more than 8 grams of equivalent lithium content or 100 watt hours (wh) per battery]. This size covers AA, AAA, 9-volt, cell phone, PDA, camera, camcorder, Gameboy, and standard laptop computer batteries.
-Passengers can also bring two (2) larger lithium ion batteries (more than 8 grams, up to 25 grams of equivalent lithium content per battery) in their carry-on. This size covers larger extended-life laptop batteries. Most consumer lithium ion batteries are below this size.

Anker's largest external battery is currently the Anker Pro 20000mAh (74 wh) which is lower than the above 100 wh limit.
Q7.  What can I do if I lose the provided accessories?
Please check to see if you have extras or contact us via email at for help.
Q8.  Anker external batteries' compatibility
Anker external batteries are compatible with Android and Apple smartphones and tablets except Asus devices ( Apple connectors are not included, please use your devices original cable).
Q9.  Can it be charged and charge other devices at the same time?
Q10.  Can it charge multiple devices simultaneously?
Yes, it can charge two devices simultaneously.
Q11.  Can it charge Samsung and Asus tablets?
Q12.  How can I tell whether the Astro Slim3 is charging or discharging?
The Astro Slim3 is designed with auto on / off settings to simplify operation. It will begin charging or discharging once the power wire is connected.
Q13.  How long does it take to fully charge this Anker external battery?
7-8 hours with a 1A output adapter.
Q14.  What do the LEDs indicate when the external battery is charging itself or other devices?
The LED lights will remain on until the connected device is fully charged or disconnected. When the Slim3 is recharging, the LED indicators will display the charge level. The LEDs will turn off automatically once the battery is fully charged.
Q15.  What if the Astro Slim3 fails to charge my devices?
a. Check that the connection between the Astro Slim3 and the electronic device is secure, or replace the cable if the current one is not functioning normally.
b. Check that the Astro Slim3 still holds a charge, and recharge it when the remaining power is low.
c. Check that the Astro Slim3's voltage is compatible with the electronic device's.
d. Make sure that the charging cable is working.
e. Please email us at duiring your 18-month warranty period if the provided acessories or the external battery have problems.
Q16.  What if the Astro Slim3 fails to recharge?
a. Check that the adapter is connected securely, or replace it if the current one is not functioning normally.
b. Check that the USB cable is connected securely, or replace it if the current one is not functioning normally.
c. Please email us at duiring your 18-month warranty period if the provided acessories or the external battery have problems.
Q17.  How can I identify the voltage specification for my device?
Please refer to your device's instruction manual, product labeling, or adapter to find this information.

You may also like

Feel free to ask questions about this product here.
Your question will be posted on this page.
Anker Customer Support and the Anker user community will do their best to quickly answer your question.



Please enter the verification code - humans only!*


Latest Post

Compatibility Question and others


I'm thinking of buying a couple of external batterries (haven't decided yet) so I was wondering if all astro slim3, astro slim2 and the astro 3E are compatible with the LG Nexus 5 and the Iphone 5. I also need to know if I have to buy any adapter or cable to connect this cellphones to the charging device.

BTW, the device comes with wall charger? Do you sell it?

Thank you very much,


Francisco Colina.

Replies(3) Collapse Report as spam Apr 19, 2014 at 10:51 AM

Yes, all the batteries will work fine with your devices. Each of the batteries comes with a cable to charge both your devices with [some, any way, others you will have to use the device's own cable for optimal charging] and to charge the battery itself.

Chargers can be found here... ...

I am really partial to the SKROSS international USB charger. It works around the world...

Reply Report as spam Apr 19, 2014 at 2:40 PM
Justin Rohr

They will all work. For your iphone you will need the USB cord, the micro-USB is built in for the Nexus 5 (or other android phones)

Any of ankers chargers will work.

Reply Report as spam Apr 19, 2014 at 5:06 PM
They will all charge your devices.The batteries will only come supplied with a Micro USB to USB cable so if any of your devices have a different input port then you will need to use the device's original cable. We sell a variety of wall chargers, feel free to take a look through our collection. The 40W 5 port charger is extremely popular!
Reply Report as spam Apr 21, 2014 at 1:30 AM


Very Disappointed - Is not reliable
Just received my Anker Slim 3 (6,000 mAh). It arrived with 3 LED’s lit. I charged it for a couple of hours and it had 4 LEDs when I started to charge my cell phone. Using the attached cord, I tried to charge my Samsung Galaxy S II (1800 mAh battery). The cell battery was at 44% charge. The Anker charged the cell for about 4 minutes, then the 4 LEDs went out and my phone showed that it wasn’t charging. I plugged the attached cord back into the Micro USB port but none of the LEDs came on. I unplugged the micro USB cord, attached the supplied USB cord and attempted to charge the Anker again. It showed 3 LEDs with the 4th blinking. I left it for another 2 hours. Once again when I tried to charge the cell phone, the Anker would only charge it for about 4 – 5 minutes and then all LEDs went out and the phone stopped charging. This happened 3 more times. On the 5th attempt to charge the Anker (Starting with 3 LEDs and the 4th blinking), I left it in until the LEDs went out. Then using the supplied cord in Output 2, I started to charge my cell phone. It charged the phone from 46% to 85%. I then disconnected that cord and using the attached micro USB it charged my cell phone to 96% and then the LEDs on the Anker went to only 1 blinking. I disconnected the Anker from my cell phone, plugged the micro USB back into the Anker and 3 LEDs came on. Once again I plugged the micro USB into my cell phone and tried to continue charging the battery. Three LEDs were on for about 1 minute and then all went out and my cell phone stopped charging. As soon as I unplugged the micro USB from my phone, 3 LEDs came back on. Tried this again on next day (cell at 35%). Cell charged to 75% and then all LEDs went out. I know all other reviews have been great, but this product did not work for me and I don't have the time to try another device. It is also very difficult to seat the micro USB in the Slim 3 slot. I returned the Anker Slim 3.
Replies(3) Collapse Report as spam Mar 11, 2014 at 5:21 PM
It's unfortunate when we buy something and get that one-in-a-million that isn't quite right. Thanks for sharing your experience with other users. It would have helped us more if you had let us know how it went when you took advantage of Anker's 18-month guarantee rather than just return it without finding out what the source of the problem was and having Anker help you with it.
Reply Report as spam Mar 11, 2014 at 6:04 PM
David Hocutt
It must be an anomaly. I use my Slim3 almost every day and it works perfectly. Contact Anker and get a replacement product ASAP!
Reply Report as spam Mar 11, 2014 at 8:39 PM
rak already returned it, David. Too bad to deny one's self such a fine product because of an unidentified issue.
Reply Report as spam Mar 12, 2014 at 1:09 AM
I'm interested in the Astro Slim 3. Does it come supplied with a charger?
Replies(4) Collapse Report as spam Feb 28, 2014 at 7:58 AM
It's getting more common not to include chargers as so many people have numerous ones and multiport chargers get more popular.
Reply Report as spam Feb 28, 2014 at 2:35 PM
It only comes with the cable, not the wall adapter
Reply Report as spam Feb 28, 2014 at 7:00 PM
It only comes with a charging cable, no charger. But you can connect/charge this external battery through your smartphone/tablet power adapter.

Package contents: Astro® Slim3 External Battery Pack, micro USB cable, instruction manual.

Or you can check out Anker power adapters and chargers:
Reply Report as spam Feb 28, 2014 at 8:15 AM
Or get a Skross World USB Charger, they're awesome and work everywhere... I leave mine plugged into the wall as a charging station and charger all my Anker batteries off of it.
Reply Report as spam Feb 28, 2014 at 8:26 AM
Nexus 4
Can anybody please tell me how many times will the Astro Slim3 be able to charge my nexus 4 after fully charging the anker!? Also is this the best buy or would you suggest some other anker product?
Replies(4) Collapse Report as spam Feb 14, 2014 at 5:44 AM
If you're into the slim factor, I suggest getting the Anker Astro 3E 10000mAh External Battery

I usually bring the Anker Astro 3E during long bus rides. For everyday commute, I use the Astro Slim2 or Slim3, lighter and just enough power to last the whole ride. For long-haul flights, I use my Anker Astro E5 15000mAh External Battery.
Reply Report as spam Feb 14, 2014 at 6:54 AM
IT Owl
Charges About Thrice
Reply Report as spam Feb 14, 2014 at 9:44 AM
It will charge your phone about three times since the Nexus 4 has a 2100mAh battery and this is 6000mAh.
Reply Report as spam Feb 15, 2014 at 11:28 AM
Manan Ghelani
Quote From orthopaedicsurgeon:What are the number of cycles for which we can charge and discharge it?
Reply Report as spam Feb 16, 2014 at 12:27 PM
Input Amps? - .8 or 1 amp
The specs above indicate the slim 3 charges at .8. However, the manual I indicates that slim 3 can be recharged at 1 amp. Which is it? Of course, I wish it could use 1.5 or 2 amps!
Replies(3) Collapse Report as spam Feb 3, 2014 at 2:37 AM
IT Owl
It recharges at 0.8A and charges devices at 1A

0.8A input - for itself to charge
1A output - for devices to charge
Reply Report as spam Feb 3, 2014 at 3:32 AM
I believe it is at 1 amp. I just noticed the discrepancies between the product description in this page and the manual that came with the product.

However, if you check the product description on Amazon, it is at 1A:

I own both the Slim2 and Slim3, the manual and product description on the Slim2 state that input: 5V/1A so I assumed it'll be the same with the Slim3.
Reply Report as spam Feb 3, 2014 at 3:44 AM
Justin Rohr
If you give the device more Amperage than what it needs, it will only take the Amps it needs, so it really doesn't matter as long as voltage lines up and its not overly huge power.
Reply Report as spam Feb 4, 2014 at 6:52 PM
Barns & Noble Nook HD 7"
Can you please tell me if this product will charge a Nook HD 7"? If not, will any of your products work for the Nook? Thanks.
Replies(2) Collapse Report as spam Feb 1, 2014 at 10:04 PM
Assuming the Nook HD 7 can charge via a USB cable then sure.
Reply Report as spam Feb 1, 2014 at 10:23 PM
IT Owl
It can I think but you're better off getting one of Anker's batteries that outputs 2A for charging
Reply Report as spam Feb 2, 2014 at 2:07 PM
Comparison (Astro Slim) to 2nd Gen Astro
The "smart" port I mainly want to know which one will charge the fastest my iPhone 5s, the 2nd Gen Astro advertises the Smart port to identify what device is connected and charge it the fastest possible! I don't see this feature on this one but is also a new model to my understanding, is it that this one doesn't include this feature? what would ultimately charge the fastest?
Replies(7) Collapse Report as spam Jan 31, 2014 at 2:54 PM
An iPad can use greater than one amp so the 2nd generation astro will charge it faster.
Reply Report as spam Feb 3, 2014 at 2:28 AM
Hi Alan,

There is a difference! The slim 3 charges at a maximum of one amp for each of the ports. The 2nd gen astro 6000 can charge a device at a maximum of 2 amps.

How significant the differences depend on your devices (ability to charge at a faster rate if the amps are available) and how many you need to charge at the same time.

PS also depends on whether you have your USB cable with you.
Reply Report as spam Jan 31, 2014 at 10:05 PM
The Anker 2nd gen. Astro 6000 can provide a maximum of 2 amps versus the Slim 3's maximum of 1 amp. There is a real difference in charge times. if your device can draw greater than 1 amp, the Astro will charge your device faster.
Reply Report as spam Jan 31, 2014 at 10:37 PM
IT Owl
Both devices will give your iphone exactly what it needs. That is 1.5A of power

Both devices are "smart" chargers
Reply Report as spam Jan 31, 2014 at 3:12 PM
The product description indicates that both ports are 1 amp.
Reply Report as spam Jan 31, 2014 at 4:05 PM
thank you so there is no really a difference in power and the speed of charging between this one and let's say 2nd Gen Astro 6000? even with an Ipad?

the only thing is that the other one has only one usb, but I like it's size, and I like the size of this one too but I don't have any devices with microusb (I'm gonna throw it on the air lol "I wish this one had 2 usb ports with it's size and slimness) but yea my main question was the charging features
Reply Report as spam Jan 31, 2014 at 6:31 PM
You get 1A of power per port on the Anker Slim 3.
Reply Report as spam Jan 31, 2014 at 9:39 PM
Will this charge Backbeat go 2
Hi will this charge my plantronics Backbeat go 2 and my nexus 4. Please let me know ASAP.
Replies(2) Collapse Report as spam Jan 30, 2014 at 12:09 PM
Yes, this external battery can charge both devices.
Reply Report as spam Jan 30, 2014 at 2:56 PM
IT Owl
Yes it will charge both with no problems
Reply Report as spam Jan 30, 2014 at 8:43 PM
Microsoft Surface
Is this device compatible with the Microsoft surface?
Replies(2) Collapse Report as spam Jan 20, 2014 at 2:54 PM
IT Owl
No the microsoft surface uses a proprietary charger and this doesn't work for it as it is not rated for tablets like that
Reply Report as spam Jan 20, 2014 at 3:06 PM
Sorry that it is not compatible with the Microsoft Surface.
Reply Report as spam Jan 27, 2014 at 1:15 AM
Wanted to get one but it's currently unavailable at Amazon, when will it be back in stock? Kind of an inconvenience since Amazon doesn't ship for free to Puerto Rico so I often combine orders to save on shipping, and I was preparing a large one now...
Replies(4) Collapse Report as spam Jan 11, 2014 at 2:01 PM
Wow it went fast. I had it in my cart yesterday and it was still in stock.

Maybe ask Anker support about when it will be available or buy another Anker External battery? They have bigger ones that are pretty awesome

Contact for more information on availability
Reply Report as spam Jan 11, 2014 at 2:42 PM
Contact and they can tell you when it'll be back in stock.
Reply Report as spam Jan 11, 2014 at 8:35 PM
Usually stocks are replenished in 30 days or less, sometimes even sooner. You may check Amazon's site every now and then to check for availability.

If you're in a rush to get an external battery, you may check out this product:

I own both the Slim2 and Slim3, and both offer flawless charging and portability. Slim2 is lighter (weight) than the latter.
Reply Report as spam Jan 11, 2014 at 11:05 PM
It's back in stock on Amazon
Reply Report as spam Jan 12, 2014 at 8:18 AM
<< < 1 2 3 4 5 > >>

Back To Top

Submit your email address here to subscribe the latest information regularly about our promotion activities and new products.

Thanks for taking the time to visit our site. If you have general questions and suggestions, we’d love to hear from you through the form below.
For more specific inquiries relating to customer service, wholesale, or media requests, feel free to visit our contact us page.