I've been thinking of a simple HUB UPS. We don't get a lot of power interruptions but during a storm its not uncommon to loose power for some number of seconds. I didn't want to deal with: AC UPS devices as they are too big and cumbersome for my Hub location Rechargeable Lithium batteries as I…

[image] JohnRob: That's why there are two diodes D4 & D5. But that just keeps power flowing from the battery to the hub and prevents backlow into the batteries. It won't shut the flow from the batteries off. Also, how are you dealing with the fact that you'll have two voltages? Assuming yo…

The pair of diodes will each drop .7 volts, or a total of 1.4, leaving 4.6 volts. Since this is less than the 5v, it should work just fine...:thinking:

[image] Ryan780: It won't shut the flow from the batteries off. That is why there are two diodes in series with the batteries and I mentioned the actual circuit may need a third. Remember this is the "simple(st)" circuit I can come up with. Besides with an additional switch (PNP or whatev…

Upon further inspection, it looks like those are Schottky diodes in the diagram. Those should minimize the voltage drop. Perhaps use regular diodes for the battery voltage drop, and the Schottky for the power supply? Just thinking out loud....

Perhaps use regular diodes for the battery voltage drop, and the Schottky for the power supply? Good thought :slight_smile: I had considered a 1N400x diode and was on the fence about using 2 different diodes or multiple schottky's. You could go either way. If you had parts laying around the 1…

you can buy ready UPS solution on aliexpress but with 18650 <a href="https://pl.aliexpress.com/item/33013126060.html?src=google&src=google&albch=shopping&acnt=494-037-6276&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&&albagn=888888&albcp=6459787116&albag=77066918093&trgt=743612850714&crea=pl33013126060&netw=u&device=c&gclid=Cj0KCQiA04XxBRD5ARIsAGFygj_2td24h23e7k_agJ_aGeN685MQNaSGDK3TmLl125r-foQ8FbohtHAaAgZrEALw_wcB&gclsrc=aw.ds" rel="nofollow noopener">click2

Thanks for the link.... interesting. But one of my goals was to stay away from rechargeable batteries :slight_smile: John

I also like simple and cheap things. I did for a specific simple project a very simple "UPS" (Ryan, I know, it's not technically an UPS :wink:) I took a 12V car battery, used but in good shape (plenty of amps), connected to a basic trickle charger plugged on the wall. An electronic device was conn…

Sounds awesome. I imagine you could also use it to charge your cell phone in a power outage.

In fact, I use this kind of things for almost important in case of (power failures): small 12V led lamps in my garage (frustrated to have no lights when power outages), my sump pump and controller, a small Li-ion battery bank with 12V/5V outputs, etc. All based on [bad] experiences :slight_smile: …

Ultra simple Hub UPS

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Rxich January 18, 2020, 6:31am 16

I know you said no lithium, but check this out. 10 bucks, no special charger needed.
Use a high quality battery(panasonic) and you'll be fine