UPS alternatives?

[archjeb]

24v 100Ah battery was $530
Inverter/charger was $649
60A breaker was $16 from Amazon
Rack Shelf (rated weight of 110#) was $46
Plug ends & SO cable from Home Depot ~ $35

A few dollars for the wire and crimp rings/lugs from the local Marine Shop for the DC side. I have a hydraulic crimp, so I just built my own for the specific lengths I needed.

I didn't count the Raspberry PI for the serial interface...since I already had that...

 

[xcentric]

Just trying to understand this: the Victron MultiPlus II e.g. https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-inverter-charger-EN.pdf says that it acts as a UPS when grid is out, but (and this may be a UK thing) I thought that when the grid was out, the inverter had to be isolated from the grid and so couldn't run the house loads? The only way that it could do is to have some loads connected to a critical loads circuit in the inverter, which is active when the grid is out. But having all the usual house loads continue to run via power to the consumer unit is not possible - I thought. Am I wrong?

 

[ricardocello]

When inverting, by default, only the critical loads are powered on Victron multiplus and quattros. The grid input is disconnected by an internal relay. When grid power is sensed to have returned and stabilizedd, the device switches back to grid power. Just like a UPS.

 

[archjeb]

That is Exactly how the Cotek INverter/Charger works that I'm using.

Cotek SC1200-124 1200W, 24V Pure Sine Inverter/Charger | DonRowe.com

The Cotek SC1200-124, 1200 Watt, 24 Volt Pure Sine Wave Inverter/Charger is a compact inverter/charger designed for mobile and off-grid applications

www.donrowe.com

I would have considered going with a Victron, but they do NOT make a US version that runs on 24v in the wattage I was looking for.
Cotek was one of the very few 24v versions in the 1200w size.

Failover from Utility to Inverter is less than 10ms...I have not seen a single glitch, so far, with this quick of a failover.

 

[Crowz]

I have a similar setup that runs my workbench chargers, window air conditioner and a few other things. The inverter runs 24/7. Its idle consumption is so low I don't even remember its there. I do notice when its powering the window air conditioner since the amp draw is much higher when its on.

This is what I use :

https://www.amazon.com/gp/product/B08MLBNCTK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[archjeb]

@Crowz

But.....

That is just an inverter.

Not an inverter/charger.

 

[ricardocello]

Cotek was one of the very few 24v versions in the 1200w size.

That one looks pretty good for my 24V server rack ups replacement, thanks.
you’ll need to program it for Lithium battery voltages via rs-232 or remote panel though

 

[ricardocello]

One thing I never see mentioned in the manuals for these things: Startup Behavior when battery is drained and power returns.
It does me no good if I am remote, and the inverter/charger drains the battery, shuts off, and never comes back on!
Physically having to be there to push a button is unacceptable. Lots of APC units had issues with this.
You don’t know until you’ve bought it.

 

[Crowz]

@Crowz

But.....

That is just an inverter.

Not an inverter/charger.

I have a pair of tracer 4215bn solar chargers and I have a victron backup charger that automatically charges the batteries from the grid if the sun doesn't come out for awhile.

 

[archjeb]

One thing I never see mentioned in the manuals for these things: Startup Behavior when battery is drained and power returns.
It does me no good if I am remote, and the inverter/charger drains the battery, shuts off, and never comes back on!
Physically having to be there to push a button is unacceptable. Lots of APC units had issues with this.
You don’t know until you’ve bought it.

It goes back to mains/service power once that returns.

Regarding LiFePo4 charge profile...ya, you have to set to custom and tweak the charge profile through the CLI/serial interface.

For now...I'm just using the GEL charge profile which keeps the voltages down to 14.4 so I shouldn't have a BMS voltage disconnect. That will not charge to full capacity...but I'm ok with that for now, until I get final configs done...and I am at a 'heck' of a lot longer run time than what I had before.

I'm hoping this is the last *UPS* I buy for this server rack -- at least for the next 10-15 years