Fast charging on-the-go power bank.

I remember a time when mobile phones were simply that — phones. We used them to call or be called and eventually, that form of communication evolved to include text messaging. Within a few short years, our phones meant for making and receiving voice calls became a futuristic handheld computer like something from Star Trek. With the added features that came with our ‘smart’ phones, came the need for more power. With those older mobile phones, it was easy enough to put it on charge when you go to bed and have enough power for the next day. But now, I will meet my power limit around 5 PM. With that in mind, I carry around portable batteries so that I don’t find myself without the use of my mobile phone. One of my favorite new portable batteries is the Gum Slim from JustMobile. 


The Gum Slim is a 10000mAh portable battery that provides power delivery and quick charge to devices. It’s considered a ‘hybrid’ battery because of its dual purpose charging potential. The USB-C Input port also acts as an output charging port for power delivery to computers and mobile devices alike. With it, you can charge up to 3 devices simultaneously. The PD port (USB-C) is meant as a charging port for the new iPad Pro which features a USB-C charging port. With the Gum Slim, you get multi-point protection circuitry which provides 5X protection against overload, over current, over voltage, short-circuiting, and overheating. 

Gum Slim PD/QC Fast Charge Hybrid Battery REVIEW


  • Simultaneously charge 3 devices 
  • USB-C and 2x USB-A output  
  • PD/QC dual-standard fast-charge 
  • Fast charge USB-C input 
  • USB-A to USB-C cable included
  • USB-C: 5V/3A, 9V/2A 12V/1.5A (PD 3.0 / QC 3.0)
  • Output:USB-A1: 5V 3A 9V 2A 12V 1.5A (QC 3.0)
  • USB-A2: 5V 3A 9V 2A 12V 1.5A (QC 3.0
  • Total: 18W
  • Capacity:10000mAh / 3.7V 37Wh
  • Indicator:4 LEDs 
  • Dimensions: 247 g; 5.4 x 2.8 x 0.6 inch


  • Just Mobile TopGum™ power pack
  • Charging Dock
  • USB to Micro USB cable
  • User manual

Gum Slim PD/QC Fast Charge Hybrid Battery REVIEW


The Gum Slim comes in a fairly standard JustMobile box. There is a transparent window on the front that shows the product inside the box off. The box has a stamp on it that states the battery is ‘flight-ready’ and pre-charged. When I pulled the battery out of the box, I tested this claim by pressing the power button. This button doesn’t really turn the battery on — it does that automatically — but it does illuminate the indicator LEDs to let you know how charged the battery is. Out of the box, the Gum Slim had three LEDs illuminated, which translates to about 75% charged. So, yes, it is charged out of the box, but not full. 

The Gum Slim has a simple design that is pretty standard for power banks of this size. One of the things I noticed right away was how close in size the battery is to the iPhone XS. After reviewing the specs of the power bank and the iPhone XS side-by-side, the similarities are quite clear. The power bank is a bit heavier than the iPhone XS and even heavier than the iPhone XS Max and to me, it’s noticeable. 

Length Width Thickness Weight
iPhone XS 5.65″ 2.79″ 0.30″ 177 grams
Gum Slim 5.40″ 2.80″ 0.60″ 247 grams

It has an aluminum exterior and stays cool while it’s charging devices or being recharged itself. The battery does not come with an AC adapter and in order to get the quickest charge for the power bank, you should use one. 

In order to test the charging capabilities of power bank, I charged my iPhone XS and a new iPad Pro. I charged them both individually. The iPhone gained 39% battery charge after 51 minutes. That ends up being a 0.76% charge per minute. The iPad Pro gained 13% after 23 minutes, which was a 0.56% gain per minute. While the iPad Pro was connected to the battery, the Apple Pencil was also being charged while it was connected to the iPad. I noticed before disconnecting the iPad from the power bank that it was down to 1 LED and it was flashing. This usually is an indicator that the battery is down to 10% and should be recharged. 


The Gum Slim portable battery is a really nice option for recharging multiple devices on the go. I really like that it doesn’t collect any heat and that it is powerful enough to charge a new iPad Pro. The USB-C port is a really nice addition to the power bank and I like that it is dual purpose. It does carry a price tag of around $50, which is a bit higher priced than other 10,000 mAh power banks. As of publishing this article, the Gum Slim is only available in black. 

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