
Ask HN: Is there a reliable UPS for the Pi 4 - dustfinger
Can anyone recommend a UPS battery pack power supply that would work well for the Pi 4 with 4 GB of RAM? I would also like to be able to power one LCD screen (from the original Kano kit) from same UPS.
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sgt
I just use a regular clunky 650VA UPS with a lead acid battery. Disadvantage
is size, but they do seem to work and the batteries last long enough. Most
have USB output for getting info on what the UPS is doing, battery level etc,
which you can then connect to the Pi.

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segfaultbuserr
I seriously don't recommended using it (at least without doing some researches
first).

Many UPS units are optimized for 50%-80% load. If you put a very light load on
an office UPS, like a lamp, a modem or a Raspberry Pi, some UPS's inverter
will drain itself quicker before the load even drains battery. Some UPS have a
light-load powersave feature, they don't even activate themselves when there's
little load. Also, most office UPS is designed for short loss of power, not as
a longterm battery-backup, so it will keep beeping until it's dead. Depending
on what the OP is trying to do, this may be unacceptable.

Due to the above problems. If I chose to use a 110/220 V UPS, I would at least
try finding one designed to supply backup power to routers and modems to
ensure that they don't have this problem.

~~~
sgt
That's very interesting. I did not know this. I saw your other response, it
almost feels like the other options are not really optimal either.

I guess the 5-volt power board is the best? But browsing through the
Aliexpress results, I could not find anything that comes already wrapped up in
a box and ready for use, as you would with a normal UPS. I suppose most people
prefer that.

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segfaultbuserr
For best results, you need to tell us: what are you going to be with your
Raspberry Pi. Are you going to use it as a desktop? A server? If so, do you
need backup power for your modem? Are you going to use it as an automatic
control system? Outdoor? Do you need protection against momentary power-loss
only? Or you need to have a longterm battery backup? How much runtime do you
need?

But in general, there are three practical solutions. You need to choose one
from your intended applications.

1\. Use an office/server UPS, 110/220 VAC. This is not recommended, many UPS
are optimized for 50%-80% load, the conversion loss of the inverter is
significant. If you put a very light load on an office UPS, like a lamp, a
modem of a Raspberry Pi, some UPS's inverter will drain itself first before
the load even drains battery. However, if you intended to use the Raspberry Pi
as a desktop or server in your home or office, or you only need to protect
brief loss of power, you SHOULD USE this option, since your LCD monitors,
external drives, etc, probably also needs a UPS. You can also try finding one
designed to supply backup power to routers and modems to avoid the light-load
problem. Other advantages include strong safety guarantee, and a good UPS has
a data port. But it seems that UPS units designed for modems, and UPS units
that have a data port is mutually-exclusive...

2\. Use a 5-volt power board. There are plenty of low-cost little boards
available on AliExpress ([https://www.aliexpress.com/af/Raspberry-Pi-
UPS.html](https://www.aliexpress.com/af/Raspberry-Pi-UPS.html)). They are
basically a 18650 Lithium-ion battery charging board with a boost converter
and a USB output. The size and efficiency made them an ideal choice if you
only need to power a single Raspberry Pi with some accessories (e.g. sensors,
screens). But there is no way to tell how much power is left in the battery
without hardware modification.

3\. Use a 12-volt backup power, with a 5-volt DC-DC converter board.
Sometimes, powering a Raspberry Pi is not enough, the modem and router also
needs backup power. In this case, using a 12-volt backup power intended for
routers and IP cameras is preferable, e.g. [https://www.amazon.com/Monerator-
Uninterruptable-Independent...](https://www.amazon.com/Monerator-
Uninterruptable-Independent-Standby-Wrieless/dp/B07RPMXQ7M/). The 5-volt power
can be obtained by using a 12-volt to 5-volt buck converter board, e.g.
[https://www.amazon.com/Converter-DROK-Regulator-Inverter-
Tra...](https://www.amazon.com/Converter-DROK-Regulator-Inverter-
Transformer/dp/B01NALDSJ0). Also, there is no way to tell how much power is
left in the battery without hardware modification.

4\. Use an open-source UPS specifically designed for Raspberry Pi, some have
battery data output, but I don't personally know any. There's an overlap
between (2) and (4).

WARNING: If you decide to choose (2), (3), or (4), remember: boards with
poorly-designed circuits, defective Lithium-ion batteries, or exposure to
outdoor environment can be very dangerous. Linked products are examples, I do
not endorse any of the products. Caveat Emptor.

~~~
dustfinger
My use case is to use the pi like a portable desktop. I would be doing:

\- run debian with exwm

\- some programming in various languages

\- browse web (run wifi)

\- occasionally play some non-resource heavy games

I would be happy if I could use the system powered by the battery for four
hours at a time. I have a ups for the pi 3B, but it often reboots when I plug
the sytem in while running. I definitely want to avoid a UPS that has a defect
that results in a system shutdown when transitioning between battery and power
from an outlet.

Thank you so much for your time writing this comprehensive answer. I think
that options two or four are the correct ones for my use case.

Thank you also for the links. I will do some more research to avoid buying an
unreliable UPS.

cheers!

