August 2020: Ordered the TalentCell Mini UPS (TalentCell SL3400) to be used as a power backup for a Sonic fiber internet. The Sonic "modem" - an ADTRAN 411 Optical network terminal (ONT) - runs on 12V DC. The "2x DC5521 male to male Power Cable" (41 cm; 16 inch) that comes with the UPS have 5.5x2.1mm plugs (outer 5.5mm, inner 2.1mm). This does *not* fit the Sonic ONT, which has takes something like a 3.5x1.35mm plug (exact dimension unknown but this one works perfectly). To solve this, I ordered(*) a separate 5.5x2.1mm-female-to-3.5x1.35mm-male adaptor.

Run-time test: I ran a test with the Sonic ONT being powered solely by the battery of the UPS. It ran for 24/7 and lasted exactly 44 hours. I had full working internet access all the time. It took approx 7 hours to charge back up to 100%.

Note: The above setup is only to power the ONT. You still need to power your WiFi/Ethernet router. If it runs on 12V, 9V, or USB, this UPS should be able to power that one as well. My ordinary router is 19V so I can't use that. However, I've got another cheap, tiny, yellow, travel 300 Gbps WiFi router that is power via USB (5V) that I'll use if the power goes out. That one I'll probably power via a separate USB battery in order to maximize the time I can keep the ONT running on battery.

Specifications:
TalentCell Mini UPS
Model: SL3400
Serial number: 202007171511
Battery: Lithium ion
Capacity: 11.1V/8.8Ah (98Wh)
Input: DC5521 12.6V/2A (inner positive, outer negative)
Output:
- 4*DC5521 (9-12.6)V/4A Max.
- 1*DC5521 9V/2A Max.
- 2*USB: 5V/2A Max.
Labels: CE, RoHS, recycle, no-trash
Over-charged/discharged protection
Short-circuit protection
Made in China
Source: From the label on the back of the UPS

EDIT 2020-09-21: Added TalentCell Mini UPS specification.
EDIT 2020-08-22: Updated with the final results of the UPS-ONT.

(*) After realized this I quickly ordered 'IBERLS Universal 5V DC Power Cable, USB to DC 5.5x2.1mm Plug Charging Cord with 10 Connector Tips(5.5x2.5, 4.8x1.7, 4.0x1.7, 4.0x1.35, 3.5x1.35, 3.0x1.1, 2.5x0.7, Micro USB, Type-C, Mini USB)'. FYI, the 5.5x2.1mm DC plug is a non-proprietary open standard, whereas the jungle of the other dimensions is often due to different companies running their own standard.

Thank you. No worries. This unit has one covered through a power outage. It still works; I've only had it a couple of weeks. Very good choice. I will update the years it lasts if it lives past the warranty period. Doesn't overheat. I don't feel the heat generated, though I know it's generating some. Electrical: engineers, scientists, and technicians have truly outdone themselves this generation. I'm astounded. Always a late bloomer, but wow! It feels really good to know that power doesn't have to be interrupted during a power outage. This power bank is just for my laptop and phone.

I have wanted a way to keep my internet on during power outages for the security system to transmit alarms for about a decade. I was looking at possibly buying a small standby UPS which would have provided about 1 hour of backup time for around the same price as this product. I knew I had about 33watts at 120v when searching.

I measured each of my 5 devices(Modem, Router/Gateway, Switch, AP, Smart Home Gateway) at DC and found they only consumed 14watts. That means the rest of the 19watts of power was wasted due to heat in the inefficient 5-1A power adapters. I also knew that it was all going to be less than 2A at 12V so this product would work. It actually comes out to be about 1.2A.

Installation is easy and makes sense because now I only have 1 power supply VS 5 supplies. I have 3-12V devices, 1-9V device and a 48v POE injector. I am still waiting on a 12V to 48V DC-DC boost converter to be delivered so it has not been connected, but should work fine once it arrives.

I decided to do a discharge test to verify the watt-hour rating and see if the supply could recover from a discharge. I disconnected the 12.6V in and connected a volt meter to the input jack. The input jack is directly connected to the cells so you can measure cell voltage regardless of the on/off switch position. As noted above I only had 4 of 5 devices connected for a total load of 10.5watts. The cell voltage started at 12.6v.

I noticed that early in the test, about 1.25 hours, it went from 4 lights to 3 lights indicating only 75% charge remaining. The cell voltage was at 11.9v. It had only discharged just over 10.5watt-hours. The test continued for 3 hours without change and the voltage was still at 11.5v. At the 4.5hr mark the cell voltage finally reached 11.1v where I believe the 50% charge point should have been, but the 75% charge light remained on. With 10.5watts at 4.5hours it had discharged 47.25watt-hours which is also about half of the 98watt-hour capacity. At the 5 hour mark the cell voltage was 11.0v. Finally at the 5hour and 25min mark the cell voltage dropped to 10.9v and the 75% light started to flicker marking only 50% charge remaining. I then stopped the test since I did not want to too deeply discharge the battery or stress my electronics with under voltage.

So one of my observations was the LEDs are really just a quick reference for if it is fully charged or partially discharged. I think whoever designed it might have not understood the nonlinear state of charge for a li-ion battery. It may be that they only had the option to design the LEDs to operate at 11.9v,10.9v, 9.9v, 8.9v with Zener diodes because that was all that was available. I don't know but it is something good to know during use. So 4 lights is around 100% to 85% and 3 lights is 85% to 40%. I did not test any further.

I think 5 and half hours of backup is excellent and if I continued it looks like it would have continues past 8 hours before dropping to 9v. I don't think I will need it that long. If I have a long power outage I will run a generator. At least if I am away from the house the internet will continue to run during a power outage. Any security related messages can be passed.

The other aspect I love about this is I now have less power adapters and the overall power consumption has dropped by consolidating power adapters. The power savings will pay for this device after about 4.5 years.

I got this as a power failure backup for may router, and it works perfectly! We had a power failure and this kept my router going for the full 2.5 hours of the power failure. It was great to have internet connection still working so I could sit in darkness and play on the laptop. Great price as well!

I bought it while my neighbor was doing electrical work (I live in a condo) and every time he turned the building power off, I lost my internet because my WiFi router had no power even though I still technically had internet. i don't know how long the battery last but even if it's just for an hour, that's enough time get out those last emails and power everything down in an organized fashion. This is a must have if you work from home.