I don’t, sorry. @borpin might be able to help here.
thanks robert.
Given a RasPi consumes 4 to 10 Watts of power, (depending on the model)
is there an issue with leaving it powered 24/7?
no. so a 5v 3a voltage source will be fine for the emonpi? thx.
Yes. That meets spec for all versions of the Pi.
Here’s a previous discussion about “UPSs” for the Pi
There’s plenty of good options available now. The main thing to look out for is that it will supply power from the mains adapter when available and flip to the battery when it is not available. A lot of similar adapters from eBay etc. will either charge the battery, or supply power, but not both.
It depends on how long you want it to run for. If the power is off, it will eventually run out. For me I use an APC 750VA UPS to run all my network gear and the Pi I currently have running HA (soon to move to Proxmox on a Laptop so built-in UPS). For me, a UPS is partly about surge protection as well although the UPS is plugged into a surge protection power strip (belt & 2 sets of braces).
bill, greebo, & borpin: thanks for the responses.
i am new to rpi but have looked at this technology with curiosity. it seems to really shine in dedicated systems applications, like the one here emoncms.
initially this will be used in a shed to monitor the pv output. the emoncms will be mounted on the wall beside the panels. i was thinking of a 270 or 300 cca lawn mower battery connected to something like this [Car Boat DC-DC 12V to 5V USB 3A 15W Converter Regulator Adapter Step Down Buck M | eBay]
the only problem with this one is that there is a 22v max input, and the solar panel might exceed this.
thanks everyone for the help. just ordered the emoncms & a temperature sensor. can’t wait to start monitoring the pv system!
That type of battery is designed to put out a large amount of current for a short time,
typically 30 to 60 seconds. As such, it won’t last very long before it “goes dead.”
(that’s why your car won’t start the morning after you find you left the dome light on the night before)
If you don’t need a “long term” solution, the mower battery would work fine. By long term, I mean
more than just a few hours. e.g. overnight, or a full day or more.
Ideally, you’ll want a battery designed to put out a comparatively smaller amount of current for a much longer interval. Deep Cycle Marine batteries come to mind here, but they fare only a bit better than the
“starting” batteries do. A trolling motor (fishing) battery would be a better choice. Golf cart batteries
would be even better yet.
I bought a USB DC-DC converter similar to the one you linked to:
but it was a disappointment. With 13.8 V at the input, the output was ~4.5 V.
That was with a 1 Amp load, which according to the device’s spec, should’ve been no problem.
Er…
emonCMS is just the software. Have you ordered the hardware as well: emonPi, a.c. adapter, 2 c.t’s, d.c power supply?
thanks bill.
after scouring various places and seeing various approaches, i found a good deal on a ups. no worries here, just plug in and forget.
Any info you can share WRT that?
Could use a device like this:
will this fit in the emonpi enclosure?
I think it is fairly clear that neither of those units (posts 22 & 23) will fit inside the emonPi.
no post 21. i know the cyberpower won’t; it is an external ups.
this will be my 1st rpi.
This may or may not be an issue, but be aware the Cyberpower UPS output isn’t a sine wave.
From the description on the seller’s page:
Uses pulse wave modulation to generate a stepped, approximated sine wave to supply cost-effective battery backup power for equipment that does not require sine wave output.
Although it’s rated at 1000VA, and the load you’ll be putting on it is considerably less than that, you might find the amount of battery powered run-time may not be as much as you’d like.