APC UPS used as an inverter. 48v 5000va 48vdc

[SamDeleted]

I've been playing with this 5000va 48v APC UPS (sua5000rmi5u) I got it at a great price , it was the biggest I could find in 48v

I'm converting it to use as an inverter in my off grid solar system,

APC Smart-UPS 5000VA 230V Rackmount/Tower - SUA5000RMI5U | APC UK

SUA5000RMI5U - APC Smart-UPS 5000VA 230V Rackmount/Tower | APC UK

www.apc.com

See here currently hooked up to 4x12v 55ah VRLA AGM in series



I've glued a board to the side, fitted breakers, RCD, a 13amp house socket (UK) & 16amp blue caravan socket. , As well as a 16amp 240vAC input

I parallel all the little DC input cables together into a 100amp breaker as you can see on the left. Other than that I've not done much work inside, it already has 2 cooling fans and a good sized heat sinks (internal pics tomorrow)

 

[SamDeleted]

 

[SamDeleted]

I got it up and running today, put it under a 1250w load, ran the batteries all the way down to 10.5v, the UPS cut off

Total run time was 1hr 17mins , 1.56kw used.





But here's where I've got an issue, the low battery warning alarm is triggering after 50 minutes of runtime. Even if the batteries aren't running low..

It's a very annoying and constant alarm

I have read this is a known issue when using these as an inverter , and there is a fix for it in the software but I'm not super computer savvy . I haven't quiet figured out how to get into the software let alone fix the problem!

Any help appreciated

 

[SamDeleted]

@Vigo

 

[SamDeleted]

I have resolved the runtime alarm problem


First of all you can calibrate the UPS for your batteries

How do I perform a Battery Calibration on my Smart-UPS? - APC USA

Also there's an input voltage sensitive button on the back with its own little LED.


If you hold the main controllers on button, the sensitive button now adjusts the runtime alarm. Set on its brightest the alarm goes off at 15%~ battery remaining


Alarm went off at 3kw




And then it cut out all together at 3.6kw, batteries read 10.5v at cutout






And that wasn't even calibrated

 

[Delmar]

The beauty of the "XL" units is they will self-calibrate during every battery check. They are designed for expansion batteries.

Did you attempt to calibrate using the Power Chute Business Edition software? It’s a free download.

 

[SamDeleted]

The beauty of the "XL" units is they will self-calibrate during every battery check. They are designed for expansion batteries.

Did you attempt to calibrate using the Power Chute Business Edition software? It’s a free download.

Interesting would've been a lot easier I imagine with an XL .. , I spoke to my UPS guy he didn't have any XL units this big & 48v , the rest were all much higher voltage


I have not tried power chute no. , Don't you need a special cable to hook up?.. their own serial cable it think

Also I haven't had a PC with a serial port for years . Can it be plugged into by USB ?

I am no expert!

Ty

 

[Delmar]

XL's are getting hard to find. I thought my UPS's were old. Mine has a USB port for a standard printer cable. You will have to find a USB>serial cable, and hope APC didn't do anything funny with the pinout.