With our smartphones, tablets and other electronic gadgets that require still more energy, the question of autonomy arises, especially when we're going on a trip, camping and access to a plug is not always guaranteed. In this case, an external backup battery can be very useful. And for an extended period a battery that can store a lot of energy is a plus. It is for this reason that I decided to test a laptop battery from 30.000mAh (!) of AUKEY, the PB – No. 39.
Content of the box and technical characteristics
1 x battery Portable 30000mAh 1 x cable MicroUSB – USB 20cm 1 x manual in 6 languages (including french, English…) 
- Technology: Load Adaptive AiPower
- Type: Li-Polymer
- Capacity: 30000mAh (111Wh)
- Output: DC 5V 4.8 A (Max)
- Microphone input: DC 5V 2A
- Lightning input: DC 5V 2A
- Dimension: 150x84x29mm (5.9×3.3×1.14 ")
- Weight: 553g
The test
My first impressions are that the battery is rather compact compared with its ability. Certainly, half a kilo is heavy in the pocket or a purse, but it's not his interest, it is a large capacity 30 000mAh battery, which can thus charge your smartphone a 10zaine of times on average (depends on the capacity of the battery of your smartphone or other device you reload)! So it is rather to put in the bag when her share for a little while. Or if several people use it during a pique nique for example, and it will successfully complete a smaller lower capacity battery to put in the handbag for example. 
It has 2 USB outputs, each output has a 5V and the combination of the two is capped at a 4.8 current A. There is only a single cable, but if you have 2, you can charge 2 devices at once with a fast speed (2.4 A, 5V). Adaptive charge technology AiPower is security for all your devices, indeed the battery can adapt to your device to not send too much power. For example, if your smartphone supports has a charge of 5V 1, 2A battery output will send current to 1 to not to damage your hardware. It will therefore provide the maximum charge rate most suited to your device within the limits of the battery itself (A 2.4). 2 output USB being identical (5V, 2.4 has adaptive) you won't need to be careful on what port you plug in any device. 
To recharge the battery, it has two entrances, a MicroUSB entrance and entrance Lightning (Apple). The battery is large capacity, the load also takes time, it takes about 16 hours load to load completely. It is possible to recharge with the 2 inputs simultaneously, and in this case 8-9 hours suffice to fully charge. This seem long, but because it offers a significant amount of autonomy (a little more than 2 weeks for my Samsung!) when you travel, it's a good compromise. When the battery is charged, an LED on the top (at the level of the indicator LEDs button) lights. When the battery is not fully charged, the LED flashes green. When the battery has a full charge, the LED flashes white. 
When you use the battery to charge a device, or even off loading, you can press the button LED indicator to see the level of battery charge, there are 3 levels. The LED flashes white when the charge level is between 70 and 100%. When the level is 30 to 70%, the LED flashes green and when the battery is almost empty, which is the level below 30%, the LED flashes red. There's a serving white LED mini flashlight, it's pretty handy. Must hold 2-3 seconds the indication battery LED button to turn it on or turn it off.
Conclusion
In conclusion I would say that this battery is very convenient when you have no outlet to door during a trip or during a single event or more. With its large capacity of 30 000mAh, it will allow many refills of your electronic devices with ease without worry about differences in power thanks to its technology AiPower system. The full charging time of the battery can be long until 4 pm, but in view of its capacity is normal and even fast when we know that with a double entry, it can be charged in 8-9 H. Lends itself more to the output with Backpack; If you need a battery just for a day and you can recharge it every night, prefer a lighter battery with a smaller capacity. Link: https://www.amazon.fr/gp/product/B01JL06LQ6/ 