My old 25year+ UPS is failing, so instead a buying a new one, I was thinking of builing one using LFP batteries and victron stuff to power my NAS, HomeAutomation, POE… in case of grid power failure.
I thought of two possibilities:
Option 1/ using a Blue Smart, Lithium SuperPack (with built-in BMS) and Phoenix VE
Option 2/ using a Multiplus and a Lithium SuperPack (with built-in BMS)
Are these two drawings possible? Can the battery communicate with the other devices so I can monitor battery level, switch off to protect battery…?
in Option 2, is the Multiplus fast enough to switch to battery?
Is it possible to choose a differrent brand for the battery with built-in BMS ? Like 48v Pylontech, Dyness, I suppose they can’t communicate with the other Victron devices… is it a problem?
My main concert is reliability of the battery (fire risk, …).
Do you think it is more secure and reliable than a portable battery like EcoFlow or Anker? And you can change batteries in these when they are old…
What do you think? Have you done this on your side?
First is as the dual conversion type UPS, with 0 ms transfer time.
Second is as a normal, online type UPS, with about 20-50 ms transfer time.
I have at one location the second one, because of the space constrains.
From my point of view the first one is ideal, with grid separation, uniform supply to the loads and better protection for them, but it’s possible to cost more.
For a battery BMS to communicate and use battery parameters into the system you also need a GX like device.
Just remember that the victron system isn’t a “true” UPS - it does not provide a clean, smoothed power source.
The AC output is linked to the AC input, so, if the grid has a brown out, the output voltage will track the input voltage, until thresholds are hit and the system disconnects and inverts.
This can cause a sufficiently large dip to reset sensitive gear.
In most other cases, and for normal equipment, the changeover is sufficient to avoid disruption.
With those adapters in your pictures, you can only monitor and configure inverter parameters.
If you want voltages, currents, cell voltages, temperatures, etc - in other words BMS parameters, you need a gx device.
If you want only generic power usage and deduct from there the info about battery, you can do without.
But if you want to monitor those parameters over internet, you still need a gx device.
So without anything, battery will self protect from over discharge by disconnecting itself if I’m right.
A GX is quite expensive. Maybe a SmartShunt will do? I prefer LAN connexion but cant find any.
The multi does not have bluetooth.
To communicate with it you either need a mk3 usb to program it, a vebus smart dongle to provide access over bluetooth via victron connect, or a GX/Pi for LAN/internet access.
For a basic use case the dongle is probably the simplest and cheapest option.
The multi will estimate soc (not as accurate as a shunt) and report voltage, current etc.
Have a look at the victron connect manual, you can also simulate any device in the app by using the demo library.
OK, I’ll have a look at the demo library.
If multiplus is switching to battery in 20-50ms, it’s may be too long to ensure all my devices do not reboot.
Do you know if Lithium SuperPack are really safe?
I have 10+ sites using Option 2 for UPS, all in rural areas that suffer a variety of grid issues on a regular basis.
They use AGM batteries due to potentially sub zero temperatures at mast sites.
UPS has function has been rock solid, never lost a device due to transfer time. And in fact I think the Multiplus is a bit more sensitive than a off-the-shelf low cost inline UPS to grid dips.
Out of approximately 1000 grid failures, I have seen 3 that caused some devices to restart. Both were bad brown-outs.
Never seen an issue with manual cutovers or, a proper blackout.
Sometimes the issue is related to the battery and loads, which isn’t the inverter’s fault.
There have been a small number of complaints over the years on the forum, mainly related to poor grids that don’t die gracefully, so it pays to remind people of the inverter’s architecture, and possible limitations, albeit rare.
