Hi i got one of these works perfekt for a little time.
Nice and small, what the estimated uptime on this one?
Entirely depends on the mAh rating of the 18650 cell that you put in it.
Assuming that Homey uses about 750mA on average (which is a wild guess), and you use a 2500mAh cell, you should be able to get about 2500/750 ~ 3 hours.
yes but this will never be a UPS solution as such, the battery being not made to be charged and discharged constantly at the same time. I would advise you to review what Arduino people develops as backup power supply; At my side after some review, I decided to go for the solution suggested earlier in this thread by @Igy meaning a true switching power supply combined with an UPS mechanism which is connected to a solid 12V sealed battery. I ordered the ADD-55 (instead of the ADD-155 selected by Igy as he requires more power) because it is enough power for me and cost less; I also ordered a 12V 4.5 Ah battery; The benefit is that Wifi and internet connection could be secured at the same time in case of power outage, also the stability of this type of power supply is much better. Once implemented I could document more about its actual outcome …
Yes please 
As promised, please find sone results regarding one potential UPS solution… and below some pictures for illustration. Please don’t hesitate to provide feedbacks relating to your own experiences.
Nota bene: I am hiding my homey in a closet for many reasons of which security, this explains why in this setup a nice casing for the UPS is not a priority although I already ordered a case for that.
The idea was to target implementing a true UPS solution with best VFM (Value For Money) possible.
Total cost was for me 63€, just below @Ruud_van_Beek cap expressed above in this thread 
Components:
- Meanwell ADD-55 switching power (55W) 2 Outputs 12V / 2.5A and 5V / 3A
- USB femelle Adapter
- Kraftmax sealed Battery 12V 4500 mAh
Stability
first output could be tuned between 11.5 and 13.8V
Second output is fixed =5V, this is the output for your Homey, it is super stable, I measured it during a week and it doesn’t fluctuate at all.
To avoid cutting the USB cable of my homey, I ordered an femelle USB adapter to have a clean connectivity with the switching power output.
The Meanwell ADD-55 incorporates an UPS system, charge the battery with limited current of 0.23A to keep high battery life duration and the battery discharge occurs only during power outage periods …
Power cut simulation
During the cut, The 5v output stays super stable and Homey doesn’t notice anything, the battery takes on nicely. My digital voltmeter doesn’t blink and display a solid constant 5V.
Backup duration testing: more testing to be done on that one, my first test gave me 3 hours of backup before Homey became unresponsive. Of course, it depends on your average Homey current consumption and on battery selected, But here this solution is very flexible, I guess I should have taken a stronger battery but this really depends on your requirement.
Thanks to all people participating in this thread of discussion and in particular @Igy who already implemented this type of solution.
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Glad to hear that you decided to use this setup. Please be aware that to effectively charge battery, you need to set 12V output to meet battery specification. In my case its 13,7V. But I do also use 12V output to power router, modem, and NAS. Those devices should handle this higher voltage, but I decided to included also another DC/DC power supply reduction from 12-48V to 12V from meanwell, just to be sure the output is correct.
Thanks for the input @Igy, shame we couldn’t adjust both types of voltage (Output 1 & Battery charge) separately then.
True in my case, the battery would require 13.5 to 13.8 V for regulation standby on charging instructions.
I guess I could optimize my 5V backup, increasing the charging tension then because I adjusted the output 1 to 12V initially.
If the moderator with the attitude was still around he would have changed the topic title. This whole topic has nothing to do with a powerbank from post 2 and down. Can imagine peeps searching for a powerbank and find this topic, all about UPS.
Thought you were a moderator? I changed the title a bit 
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To be honest, I don’t think a lot of people really mind topic drift. It keeps conversations interesting (just like in real life!) and being able to introduce alternative ways of looking at a particular topic you may be able to help people out anyway.
Strict moderation is a great way to stiffle such conversations, and forcing people to post their questions in very generic topics that are already dozens or hundreds of posts long, which happens often when people ask question about particular apps or devices, is a good way to complete lose track of particular discussion threads (topics within topics within topics).
Thankfully, the search results show context so people searching for powerbanks can cherrypick the posts that actually talk about powerbanks. They’re not limited to just being able to see topic titles.
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U are right. A lot of people don’t mind at all!
But just a tiny adjustment like the TS did and we have the best of both worlds aye?
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Regarding the substance, Powerbanks and UPS are two sides of the same discussion around how to get a solution to prevent your Homey against Power Outage
And that will bring us back to post 2,3 and 4. Best not use a powerbank for that but a UPS!
Agreed 
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I am following-up on my previous post to share on additional results for Backup duration. Indeed across our discussion point with @Igy , the charging nominal tension should be adjusted and actually we lose the possibility to have a 12 volts output if the battery requires 13.7V like mine.
We could better understand now why the DC Output is given for 13.8V and the BAT Charge for 13.4V (See below specifications).
The Output 1 is adjustable between 11.5V and 13.8V but if you want to guarantee a good backup duration you need to adjust to the battery charging requirements.
After doing this, I measured the battery discharge and Homey voltage accross Time.
Please find following diagram to illustrate the results.
More in line with the theoretical target (Homey average supply power in my case of 5Vx380mA) than for primary result: Above 12 hours backup time before Homey disconnects …
The Homey voltage was steadily 5 Volts all the time until time where the Battery voltage went below 10.6 volts (the Homey voltage abruptly decreased down to 0)
In conclusion, I could highly recommend this type of option. You could also easily increase the backup maximum duration or output power delivered at backup for few euros more (using a 7Ah battery instead of 4.5Ah).
Later on I will have to also backup my wifi network but for that I would need first to find an option to relocate my optic fiber input. Then I will review what to do for the 12 Volts backup required…
Obviously, this kind of setup needs to be hidden and tamper proof. Too many wires going around, right? Where do you keep it, in some cupboard drawer or?
Just hiding it into an high cupboard (2m high) very well located in the center of my house.
Better for security for sure and I wouldn’t expose the homey “design” and cables around thus not really an issue for me. Otherwise to be honest not big difference with a charger once fitted in appropriate box where the cable management is handled properly, just a bigger box is needed
This DC/DC converter will solve your 12V problem https://www.meanwell-web.com/en-gb/dc-dc-enclosed-converter-input-9-2-18vdc-output-sd--50a--12
Regarding place to store, small rack in my case can host almost everything.
Only wifi router and Homey is outside, because of wireless signal.
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Hi there, I ordered 1 week ago a EasyAcc Powerbank 20.000. It is able to „charge-through“ and has 4 USB slots. I installed it and it works very well. I connected Homey pro, a Blink camera sync module and my Netatmo weatherstation. I can plug out the power supply and it still goes on working. I charge it with an old 10W Apple iPad charger.
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