On Mon, 26 Jun 2017 11:21:58 +1200, 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.
>
Pimoroni and http://www.piups.net/ sell Pi UPSes but, after you add a
battery, they may be more expensive than you're expecting.

But, there's always DIY:

Using an in-line 6 or 12 v SLA (Sealed Lead-Acid battery) together with
an off-the-shelf battery charger plus something that outputs constant 5v
when driven by the battery is probably the easiest DIY approach.

Notes:

1) Size the SLA to match your measured load and the length of time the
system must run if there's a mains outage.

2) The SLA charger must be able to output more power than the RPi plus
connected devices needs or the battery will slowly drain.

3) The SLA charger should be a 2 or 3 stage unit that goes into float
mode when the SLA is full and can go back to charge mode as the RPi pulls
the battery down below its float level. Not all can go back into float
mode, so ask the vendor specifically about that (in writing?).

4) This is probably not much cheaper than buying one from the two
suppliers mentioned above: if you want something with more than toy
capacity its going to cost more than the RPi by the time you add sensible
sized batteries.

5) An SLA of a given capacity is cheaper than an equivalent rechargeable
lithium battery and MUCH less likely to catch file than a Li Ion battery.


--
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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