Stacking UPS? (Without Transfer Switch)

[PinkFloydEffect]

I am trying to improve our company's data room redundancy, working with the UPS units we have on hand. I have two identical model Tripplite Smart1500RMXL2UA units to use with our switch rack. Some switches are used more than others some days, so I do not want to just connect half them to one UPS and the other half to the second UPS. I am after a load balancing solution, we do have some transfer switches but I am trying to reserve them for other uses.

I noticed there is a 36V-50A connector on the back corner of both units...likely for external battery banks. Is there a way I can link the two units using these connections so that there is load balancing functionality?

 

[OzarkEdge]

I noticed there is a 36V-50A connector on the back corner of both units...likely for external battery banks. Is there a way I can link the two units using these connections so that there is load balancing functionality?

I would RTFM.

OE

 

[CharlieTX]

Linking the DC Bus might actually work (I never considered this), but my gut tells me that it would be a really bad idea. You still wouldn't get more peak output from the inverter.

I thinking running cheap aftermarket batteries on those connections would be far safer, and give you more runtime.

 

[PinkFloydEffect]

I reached out to Tripplite and they said no.

More peak power is not my goal, its just extended runtime between the two evenly. If anything, I might try connecting both DC buses to the same battery bank.

 

[coxhaus]

I don't think UPSs work like load balancing switches. I think you divide them up. If you want more power buy a bigger UPS or battery extension. The idea with redundancy is not to make it too complex. I have to confess I only have used APC in the past.

 

[PinkFloydEffect]

I already have multiple 5000VA APC units with external battery banks but these Tripplites were free from another project. I will either put a transfer switch between the two or use just one with a large external bank.

 

[System Error Message]

I am trying to improve our company's data room redundancy, working with the UPS units we have on hand. I have two identical model Tripplite Smart1500RMXL2UA units to use with our switch rack. Some switches are used more than others some days, so I do not want to just connect half them to one UPS and the other half to the second UPS. I am after a load balancing solution, we do have some transfer switches but I am trying to reserve them for other uses.

I noticed there is a 36V-50A connector on the back corner of both units...likely for external battery banks. Is there a way I can link the two units using these connections so that there is load balancing functionality?

Yes you can link them directly on the output to load balance them but there are a few things you need to understand about passive linking. in EEE it only increases the max output by 20%, that means if you use thicker cables you could get 60A max.

It will not perfectly drain them. It may drain one battery more than the other, but you do get double the capacity in total. The reason for this is that each battery is not perfect so it will only drain the one that outputs slightly more voltage. Since batteries vary in condition even when fully charged, they output different voltages at different loads. That is why you have a voltage range at the back and why such equipment are designed to handle a range of voltages as it is more efficient to voltage switch on the smaller scale than it is on the larger scale, so this gives longer battery operation for the same capacity.

By all means, for redundancy go ahead and do it, just remember the amp limits of both the battery and cable that they do not stack even if capacities do, so do not exceed the output of 1 battery.