UPS alternatives?

[archjeb]

The big or the small one?
On the big one I only have necessary loads and we usually never have outages longer than 3 hours, with PV input it can hold up for that time. The small one is just the ups for my rack, when I see that its a longer outage I shut everything besides router and wifi off so that it can last 5 to 6 hours too

Ya, the small one.

My issue is...some times, I'm not around and want everything to gracefully shutdown; which is why I have the Raspberry pi with my existing APC/Cyberpower setup, which after a couple minutes of no power, it will log in and gracefully shutdown a bunch of VMs running on a couple of ESXi hosts.

The scripts also slack message me about the status along the way. And then using the NUT driver interface...will shut the UPS down and power back up when utility power returns. I want to do something similar but with longer runtime and something that is easier to maintain. These dinky little 9Ah Lead Acid batteries and little dinky UPS are just not able to handle much of a runtime.

I just need a simple API (heck even a simple RS232 interface is fine) to interact with the UPS/Inverter. If I have to screen scrap via a serial connection, I can use pexpect if I have to.

 

[A.Justice]

I've modified a few UPS's to take lithium batteries. I disabled the charging circuit, and charge them externally with a lithium charger.

 

[fmeili1]

Ya, the small one.

My issue is...some times, I'm not around and want everything to gracefully shutdown; which is why I have the Raspberry pi with my existing APC/Cyberpower setup, which after a couple minutes of no power, it will log in and gracefully shutdown a bunch of VMs running on a couple of ESXi hosts.

The scripts also slack message me about the status along the way. And then using the NUT driver interface...will shut the UPS down and power back up when utility power returns. I want to do something similar but with longer runtime and something that is easier to maintain. These dinky little 9Ah Lead Acid batteries and little dinky UPS are just not able to handle much of a runtime.

I just need a simple API (heck even a simple RS232 interface is fine) to interact with the UPS/Inverter. If I have to screen scrap via a serial connection, I can use pexpect if I have to.

In this Tasmota issue #8433 are some possible options linked how to communicate with Victron components. It may be helpful to implement something DIY, ESP8266/ESP32 or RaspberryPi based, to implement graceful shutdown features. In case of a RaspberryPi you may execute some ssh command to remote shutdown your systems if the SOC drops below a specific value... just an idea (I don't own large Victron inverters).

 

[archjeb]

I've modified a few UPS's to take lithium batteries. I disabled the charging circuit, and charge them externally with a lithium charger.

I was thinking of doing something similar. Having a schematic would help isolate what to clip (this is assuming there is no dip switch or anything to actually disable it).


Here is a pic of the control/inverter board on one of the Cyberpower UPSs.

Would love to know if someone has already figured out how to disable charging

 

[archjeb]

Actually I figured it out.

I'm getting 27VDC output from Schottky Rectifier Diode (circled) SS26. By severing the cathode side (pointed towards the battery connection); you cut off the pseudo charge circuit.




This also means that the control board fully relies on the battery for power (the display, etc). As long as there is at least 24vdc on the battery terminals; it should continue to function just fine. On AC power, there is a relay that provides pass through.


The bad thing is...I took this out of the junk pile and found there is something already broken on the inverter circuit...so I'll have to find another one and test/confirm this modification.

 

[archjeb]

I think I found something that might work. I'll give them a call in the morning and see if I can chat with them a little more. It looks like it has an RS232 interface that I might be able to write an interface to.

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 don't know why its so hard to find a 24v lower wattage inverter/charger for 120VAC output. It would seem like the demand would be high for these in vans, boats, etc in the US. I'm surprised the Victron Multiplus's are not available in 120VAC for the lower wattage units.

 

[PyroRider]

I've modified a few UPS's to take lithium batteries. I disabled the charging circuit, and charge them externally with a lithium charger.

Tried that with an Eaton ECO 1200, Toasted it.
Edit:
Btw, If anyone (from germany) needs 2 Eaton Eco ups boards, one 800VA one 1200VA, cant remember which one exactly I toasted and which one worked but I gave up, contact me

 

[PyroRider]

Ya, the small one.

My issue is...some times, I'm not around and want everything to gracefully shutdown; which is why I have the Raspberry pi with my existing APC/Cyberpower setup, which after a couple minutes of no power, it will log in and gracefully shutdown a bunch of VMs running on a couple of ESXi hosts.

The scripts also slack message me about the status along the way. And then using the NUT driver interface...will shut the UPS down and power back up when utility power returns. I want to do something similar but with longer runtime and something that is easier to maintain. These dinky little 9Ah Lead Acid batteries and little dinky UPS are just not able to handle much of a runtime.

I just need a simple API (heck even a simple RS232 interface is fine) to interact with the UPS/Inverter. If I have to screen scrap via a serial connection, I can use pexpect if I have to.

The small Multiplus has a VE.Bus port, but you usually need an expensive adapter to connect it to usb and even then I can't say what you can read out or do with the interface.
Would be simpler to put an ESP in to measure battery voltage and maybe a DC current sensor or shunt to calculate remaining time

 

[archjeb]

I'm going to give the Cotek inverter/charger a shot. Just got off the phone with them. Looks like it will work just fine. the RJ12 has RS232 pins and I can easily write an interface with pexpect to do what I need to do. Via the same interface I can configure the charge profile/voltage and it has a configuration for the charge current. Switch over time is spec'd at 10ms so that should work.

Auto Neutral/ground bonding when on battery...floating neutral in bypass mode...looks like it hits all the marks.

https://www.cotek.com.tw/sc-1200-1200w

The local distributor is just 20min away that handles the warranty - so pretty much local distribution.

I'm still shocked that there are not more 24v inverter/chargers in this power output for the US market.

 

[A.Justice]

I was thinking of doing something similar. Having a schematic would help isolate what to clip (this is assuming there is no dip switch or anything to actually disable it).


Here is a pic of the control/inverter board on one of the Cyberpower UPSs.

Would love to know if someone has already figured out how to disable charging
View attachment 190981

Honestly, without having the board in front of me I couldn't tell you much. The most simple way to do it is to add a diode to the charging circuit. Power can come back to the system, but not go into the battery. However, that only works on some UPS's, others will read the battery at 0 volts and not function.

I was able to poke around with a multimeter and find to charging circuit, and then cut a few leads. But that's all model specific.

 

[A.Justice]

I think it's also worth noting that I have added external fans to every one of my UPS's. The transformers in those things get ridiculously hot, and I'm surprised the manufacturer doesn't have a fan in them. The transformer temps were approaching 150° f, I added the fan, and now it hovers around 90°f. It's pretty simple to solder up a 12 volt fan with a switch and cut a small hole in the side of the unit near the transformer as an air inlet. This seems to make my UPS's last much longer.

 

[archjeb]

Honestly, without having the board in front of me I couldn't tell you much. The most simple way to do it is to add a diode to the charging circuit. Power can come back to the system, but not go into the battery. However, that only works on some UPS's, others will read the battery at 0 volts and not function.

I was able to poke around with a multimeter and find to charging circuit, and then cut a few leads. But that's all model specific.

In post #30, I was actually able to get it on the bench and figure it out. I decided to go down the Inverter/Charger path. Its on order. Will report how it goes after I get it on the bench and test it.

 

[JMACK61]

I've modified a few UPS's to take lithium batteries. I disabled the charging circuit, and charge them externally with a lithium charger.

I used two APC SU2200 UPS’s as is with my 16s50p, 26650 DIY powerwall. The chargers are not strong enough to do any damage to a 48 volt 150 Ah battery. Most the charging comes from my solar panels. Rarely is the UPS on Utility power put I have an external relay on the UPS power cord to take me to Utility power should I get too low on battery power. This keeps power to the house and charge the battery a little bit because that charger would take several days to charge a 150 Ah battery. Took 24 hours to charge the dinky 9Ah sealed leads that it comes with.

 

[archjeb]

Alright, I've got the inverter/charger and 100Ah 24v LiFePo4 pack sitting in the rack. Its been running for a couple weeks now and its working great!

Ended up using the following battery:

Of course did a full battery capacity test beforehand - it was a little over 101Ah.


I still need to finish building a shroud/cover with some HDPE that I have on hand. And also need to get the Serial interface connected to the Raspberry PI for management. But I've ran it with a constant load for 1 hour at 1200W on battery without any issues - and still capacity left. My target is 1 hour which is significantly better than the 10min I was getting from a Cyberpower UPS. So its working as advertised and covers my needs to get enough run time to gracefully shut down the equipment or to get the generator running. Over an hour of runtime is more than adequate.





The Cotek SC1200-124 1200W - from Don Rowe.com is what I ended up with. It was one of the very few 24V inverter/chargers available in the wattage/size.





Thanks folks for the feedback and the discuss. I'm happy with what I ended up with.

 

[solar8484]

What's the total cost?

 

[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