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The Amazon Echo Dot is a neat device and pretty portable, except that it doesn't have a battery and it takes a minute or so to reboot if you unplug it from one place and plug it in another.

I've used a li-ion powerbank pack attached to the Dot for a year now. Very convenient to be able to carry the Echo Dot to another room to continue listening to a podcast. But to do that, it has to remain plugged in to the charger full time. Recently I noticed that the rectangular package had popped apart. Apparently the Li-Ion cells swelled under continuous charge. Not confidence building. So, what I really need is a rig where the Dot can be running on AC power, I plug in a battery before unplugging the AC supply, carry it to my destination, and then either plug into AC again or continue running on battery for as long as it lasts. And then I recharge the battery separately. I'm sure such a thing is possible electronically but I've never seen one. An OTG octopus might work but I'm not sure.

To be explicit, I think I need something that has a micro-USB output (which goes into the Dot) and two micro-usb inputs. One input would be for the battery pack and the other for output from a wall wart. And I need to be able to plug and unplug either one (though obviously not both) without resetting the Dot or shorting out the power supplies.

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closed as off-topic by Dmitry Grigoryev, Michel Keijzers, RoyC, PeterJ, Finbarr Mar 26 '18 at 9:35

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  • \$\begingroup\$ A very poorly researched question. It appears that there are tons of "mini DC UPS" on the market. \$\endgroup\$ – Ale..chenski Mar 23 '18 at 21:39
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    \$\begingroup\$ Given that OP never mentioned a UPS once and likely did not know what a "mini DC UPS" was or that such a thing existed, how exactly is this very a poorly researched question? \$\endgroup\$ – user171804 Mar 23 '18 at 22:10
  • \$\begingroup\$ @CharlesM, because the function he describes is "UPS". Uninterruptible supply. Functional without reset. Everyone near EE area should know this. \$\endgroup\$ – Ale..chenski Mar 24 '18 at 4:31
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You need a device called "micro UPS" - miniature Uninterruptable Power Supply. Or "Mini DC UPS". One of this kind (for DYI apps) is offered by Adafruit, kit #1944,

enter image description here

see Mouser/Digikey/Arrow/whatever.

Or a device in a Rpi3 format:

enter image description here

CORRECTION: I withdraw my recommendation for Adafruit 1944 Kit. After examining their circuitry, I found that it doesn't manage the battery properly: when always on input supply AND having a load on 5V booster side, the Li-ion cell will be always subjected to charge voltage, and therefore will be overcharged eventually, resulting in bad batteries. Avoid this kit.

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    \$\begingroup\$ Hmm. So I'm not supposed to say thanks. OK. But I do appreciate the help. Actually, I am a chemical engineer, albeit an old one. And I did search the forum for continuous charging and lithium ion batteries. Learned a lot. And I have an UPS under the desk for my big iron. But it never occurred to me that there were micro versions. We all have our blind spots. Grateful to @Ali Chen \$\endgroup\$ – pwright2 Mar 24 '18 at 19:28
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    \$\begingroup\$ Brother @ali chen, I beg your indulgence a bit further. The Adafruit 1000C seems almost perfect ... except. The 1000C expects the battery side to be putting out 3.7 to 4.2V and then boosts it to 5.2. I'd like to use any commercial powerbank as the battery side, which means a 5V output. Since I doubt that Adafruit is interested in redesigning their circuit, I am visualizing something simple that would go between the 5V powerbank output and the Adafruit input that would drop the voltage to an acceptable range. (A Zener he opines, waving his hands as if he knew what he was talking about?) \$\endgroup\$ – pwright2 Mar 24 '18 at 22:13
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    \$\begingroup\$ Brethren @pwright2, will this one work for you? amazon.com/dp/B072NRXMN2 (still found by Google for key-phrase "mini DC UPS"). A good power management system, uninterruptible smooth supply while caring for battery, is not an easy feat, just read a bit about details in description... And wouldn't the Alexa be smart enough to suggest the right kind of solution in first place? Just curious... \$\endgroup\$ – Ale..chenski Mar 24 '18 at 23:02
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    \$\begingroup\$ Alexa is sweet, polite, and limited. There are batteries sold for the Dot. Costing about what the solutions here present. But I have no idea whether they are protected or merely counting on mother nature to be kind. The new link looks very nice. Once again I offer the forbidden thank you. \$\endgroup\$ – pwright2 Mar 24 '18 at 23:17

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