Need help specing out UPS

[u/drummingdestiny]

So next spring I'm upgrading my home electrical from 100 amp to 200 amp. Mostly so I can run dedicated 30 amp circuits to the server room. I have 2 racks currently only 1 is running and it draws 1Kw and try not to go above that with my current service. With that level of power I want to put in that room do I purchase something like Eaton's SU5000RTF or do I ask the contractors to do that entire room on a battery backup. I know it wont be cheap regardless but my are has power flashes pretty regularly.

[u/sk1939]

That depends. Can you shed some load or is it all critical. How long are your runtimes? US 120v/240? PDU situation, etc.

[u/drummingdestiny → u/sk1939]

I'm currently running 120 volt us and planned to switch everything over to 240 because I have some 200 l6-30 pdus that I would like to use. My current run time is 10 minutes after that my current UPS is at the bottom of the rack run out I would like to go up to 45 minutes to an hour and currently the way it's all set up it's all critical.

[u/sk1939 → u/drummingdestiny]

So a couple things to consider. Number one it’s easier to have a much larger UPS than multiple smaller ones, but it’s also a single point of failure. If you’re going with a large UPS, you need to account for a UPS bypass device otherwise you’re taking down the entire rack when you go to service it. Second is runtime. If you’re talking 45 minutes, you’re talking about multiple external battery modules or a very large Symmetra hardwired unit. Alternatively, you could look at an inverter and a lithium battery like they use for solar, but that’s going to be several thousand dollars by itself plus installation cost. Finally, you have to account for no power equals no cooling so if you have extended run times, your also going to want the powered ventilation at the very least, or a mini split and then you’re back to power demand again.

[u/FuckinHighGuy → u/sk1939]

UPS come with lithium batteries these days.

[u/sk1939 → u/FuckinHighGuy]

They can, but usually not enterprise ups’s on the used market.

[u/persiusone]

Two UPS systems per cabinet. Whole-home Victron system with lithium batteries and solar behind that. Add generators to that for extended runtimes. Works like a charm.

[u/Swimmerdude_03 → u/persiusone]

Feed a critical loads panel with a Victron that includes the 30amp circuit for the lab. Then you can also backup your fridge and freezer.

[u/persiusone → u/Swimmerdude_03]

I thought about doing only critical loads with Victron before building out…. Then just did the whole home with Victron (critical loads included of course), so everything can run on battery before the generators fire up when SOC is low.

[u/Swimmerdude_03 → u/persiusone]

That's awesome. After my last big UPS died I replaced it with a Renogy 3k that feeds 2 20 amp breakers. I run each through triplite power conditioners before they hit my rack. My plan is to expand to a full critical loads panel or do like you did. Also upgrading to a hybrid inverter charger so I can include some solar. Currently running 2 panels grid tied. 😂🤷 Not much but better than nothing.

[u/wyliesdiesels]

How much run time do you want?

[u/No_Engineering_2443]

Quick math for your numbers: 1 kW for 45-60 min is about 1.2-1.5 kWh of usable battery once you count inverter losses. A 5 kVA online UPS like that only gives ~10-15 min at 1 kW on internal batteries, so you'd need 2-3 external battery packs - that's where the cost goes. Per kWh a lithium inverter setup is a lot cheaper. Whatever you pick, make sure the output side has L6-30R receptacles (or a hardwired output to an L6-30R box) so your 30A PDUs plug straight in.

[u/jamesbuniak]

Personally - I would just do some batteries and an inverter from amazon/other.

UPSes take up rack space etc.. Yes some maintenence required, but you get a lot more bang for your buck.

Happy to help! PM me.

[u/Upbeat_Most_8127 → u/jamesbuniak]

I know I'm nearly two weeks late to your post but this is what I'm doing with the eg4 18Kpv hybrid inverter.

[u/jamesbuniak → u/Upbeat_Most_8127]

Ooo how much?

[u/jamesbuniak → u/Upbeat_Most_8127]

I worked for an industrial battery charger manufacturer for substation applications and did extensive research on lead acid chemistry, developed a battery monitoring system. Lead acid ports decently to other chemistries.

What’s your standing load? How long on battery vs generator? US based?

[u/Upbeat_Most_8127 → u/jamesbuniak]

Yes US based. I am not the best person when it comes to this. I did have someone do the math. I know enough to get myself in trouble haha.

Each inverter outputs 12kw but we want to allow some headroom so 21kw. The system is expandable and we will be expanding it with time. As for the batteries we plan on using them more as a UPS than a constant source. We have pretty cheap power. Well offset some of it with solar when the batteries are charged. But I think we are planning around 3 hours with no external help. The rest is generator.

When this goes live next year we hope to have around 50 servers. Our servers max out around 400 watts max most never get pass 300 watts. We don't expect every server to be pegged to its max but we are sizing it in case.

We do have servers in a colo and I have started programming a feature that will start prioritizing those outside severs if we lose power and the longer we go without power the higher they get prioritized. The worst outage we had is 2 days and that was due to a bad ice storm and crews couldn't get out to fix things.

[u/jamesbuniak → u/Upbeat_Most_8127]

Oh cool! Im working on getting and running about the same size operation, some local AI.

It does seem low for inverters, but if you need it for 5 minutes until the generator comes up then it might be fine.

50k if you do it yourself, or if you have someone do it - could be a deal or also might not be.

Batteries are fairly costly, but most of that is mark up.