Graham. wrote on 6/28/2017 8:08 PM:
> On Mon, 26 Jun 2017 11:21:58 +1200,
> nospam.Rick.Christian@f377.n135.z1.binkp.net (Rick Christian) wrote:
>
>>
>>   Hello everybody!
>>
>> There was some discussion on setting up various USB batteries for a sort of
>> PiUPS...
>>
>> I'd like to get some feedback on the devices that users have found to WORK
in
>> the  role of PiUPS. Got a setup that needs to have this, and using even el
>> cheapo APC AC UPS salavaged from places and Ebay and putting $40 batteries
in
>> them seems out of line.
>>
>> Looked at the Amazon Basics 16.1AH USB battery but it cuts off the power
ports
>> when you charge. Some one there was looking to do exactly what I want, and
>> foudn out its useless.
>>
>> Any one have known working devices, with *US* purchasing options.
>>
>> Ideally it would have a setup like the Amazon units 2 USB port for power, a
>> microUSB for charging...plug Pi into one port, charger into uUSB port, and
not
>> worry about the stray power glitches... it doesn't even really have to run
that
>> long, 5-10 minutes till gen set auto starts.
>>
>> In my current time frame, plug and play is needed. I don't really have time
to
>> build something.
>>
>> Thanks.
>>
>>
>>
>> Rick
>>
>>
>> ... Ding Dong the Witch is DEAD! I Made America Great Again! President
Trump!
>
> I used a dollar store USB power-bank as a pi UPS. Like you say it
> doesn't have pass-through  while it's charging so, I added
> pass-through by wiring the regular PSU and the power-bank output in
> parallel but with a  Schottky diode in series with +ve of the
> power-bank output
> A separate PSU was used to charge the powerbank, I didn't investigate
> if one PSU could do both tasks.
> The project consisted of a Pi Zero wifi dongle and 1602 LCD display.
> Failover and power restoration  was seamless and it ran for about an
> hour on the single 18650 in the powerbank.

Seems amazingly simple.  So the makers of the power bank could make their
device into a rPi UPS by simply adding a couple of Schottkey diodes.  I
can't imagine a single PSU wouldn't work unless there are separate grounds
on input and output for some reason.

--

Rick C

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