Daisy chaining pure sine wave UPS units

[Syntaxvgm]

I know it's not typically advised to daisy chain UPS units, but I don't see why I couldn't chain together some pure sine units? In fact, I've seen it done before. APCs website simply says it's not really necessary to run more than two, and mentions simulated since wave not working for this. Obviously the first unit would need to not exceed the draw of the second at any time, even when fully load and charging.

 

Any thoughts?

[KarathKasun]

Why?

[unijab]

Can you? yes.

Should you? no

 

 

 

 

 

[leadeater]

If you want longer run time most UPS support battery expansion modules, which have larger battery units in them than the UPS.

[dalekphalm]

1 hour ago, leadeater said:

If you want longer run time most UPS support battery expansion modules, which have larger battery units in them than the UPS.

Agreed

 

5 hours ago, Syntaxvgm said:

I know it's not typically advised to daisy chain UPS units, but I don't see why I couldn't chain together some pure sine units? In fact, I've seen it done before. APCs website simply says it's not really necessary to run more than two, and mentions simulated since wave not working for this. Obviously the first unit would need to not exceed the draw of the second at any time, even when fully load and charging.

 

Any thoughts?

What is the reason for you doing this?

 

Any enterprise grade UPS will support additional battery packs to give out more battery time - most can accommodate up to 4 additional battery packs.

 

If you need more outlets, just buy a PDU (Power Distribution Unit - basically a glorified power bar) - or if in a pinch, just use regular power bars, but NEVER daisy chain the power bars.

 

Outside of needing more battery time, or more outlets, I cannot possibly think of what you're trying to achieve.

[Syntaxvgm]

2 hours ago, dalekphalm said:

Agreed

 

What is the reason for you doing this?

 

Any enterprise grade UPS will support additional battery packs to give out more battery time - most can accommodate up to 4 additional battery packs.

 

If you need more outlets, just buy a PDU (Power Distribution Unit - basically a glorified power bar) - or if in a pinch, just use regular power bars, but NEVER daisy chain the power bars.

 

Outside of needing more battery time, or more outlets, I cannot possibly think of what you're trying to achieve.

 

4 hours ago, leadeater said:

If you want longer run time most UPS support battery expansion modules, which have larger battery units in them than the UPS.

The price to runtime gap between a pure sine consumer model that takes 1 expansion daisy changed with an identical set vs any solution that allows me to properly expand is very high. Much much cheaper to get the runtime I want to target. I'm talking 650-700$ vs 2500$ for a good used unit and equivalent batteries. I only want to do from about 50w to just over 300 watts total draw and get over sized units to maximize run time. 

 

Lol why would i need more outlets? And you can daisy chain a power bar all you want, just loading appropriately so long as it's not exposed to people with the bright idea to plug more in. Do it for monitors and stuff all the time. Where a killawatt comes in handy. Typically try to use smaller ones or just splitting extensions so you can't plug more than I have in them. The warnings on surge protects are not about the surge suppression function interacting, but really just to prevent dumbasses overloading stuff, which they do, even on one strip. I have plenty of stories of equipment ruined with daisy chaining power strips, but all of those stories well exceed the rated 10 or 15 amps. Anyone with half a brain doesn't even let it get close to that, especially given that most residential breakers in have area have 15 amp circuits, so if you approach that on one outlet...uh have fun when someone plugs something else in on the other side of the wall/room. 

I typically don't plug everything into the battery side of a ups anyway. Just like, the computers, one screen, and a low wattage light. The idea is for it to shut everything down, then still run a very low wattage light and a small security camera system for a few hours, until I'm home and have the generator hooked up.

 

So, back to my question 

 

So, my main concern is does a pure sine wave (not simulated/pwm) ups have a clean enough output to not trigger the second ups? APC seems to think so, but they're the only good source that really seems to talk about daisy chaining  ups and specifically mentions not using simulated sine wave. In fact all threads I see about not doing this mention that the power provided on battery is the modified square waves with the micro power gaps causing issues, but never really talked about in the context of pure sine wave models. 

 

I want someone to tell me why a pure sine wave ups cant power another ups if that's the case. (keep in mind, I'm not going to overload the "mother" unit. That would be stupid)

[leadeater]

16 minutes ago, Syntaxvgm said:

I want someone to tell me why a pure sine wave ups cant power another ups if that's the case. (keep in mind, I'm not going to overload the "mother" unit. That would be stupid)

Pure can so if you need to chain a pure with simulated then the pure sine wave UPS would have to feed in to the simulated.

 

What messes with the UPSs is the power factor correction which simulated sine would cause havoc with and destroy efficiency meaning you'd get next to no run time at all. Simulated sine is either going to trip power protection conditions or fight with power correction mechanisms the UPS offers.

 

The other big reason not to is the efficiency loss or effective capacity you get at the end of the chain and the load at the start. Two 3kva UPS chained can't actually provide 3kva load due to the loss, if it's 10% then you can only connect up a 2.7kva load to the end of the chain as the start of the chain will see it as 3kva. This does apply to pure sine.

[Syntaxvgm]

1 minute ago, leadeater said:

Pure can so if you need to chain a pure with simulated then the pure sine wave UPS would have to feed in to the simulated.

 

What messes with the UPSs is the power factor correction which simulated sine would cause havoc with and destroy efficiency meaning you'd get next to no run time at all. Simulated sine is either going to trip power protection conditions or fight with power correction mechanisms the UPS offers.

 

The other big reason not to is the efficiency loss or effect capacity you get at the end of the chain and the load at the start. Two 3kva UPS chained can't actually provide 3kva load due to the loss, if it's 10% then you can only connect up a 2.7kva load to the end of the chain as the start of the chain will see it as 3kva. This does apply to pure sin.

Yah I'm aware of the loss. The consumer ones I'm looking at are 900w or more, and my load will not much exceed 300w on the battery side. I would intend to have the unit at the top be pure sine, or both really. Simulated sine does some weird things on some stuff that's not meant to run it, and who knows I may want change what I have on the end of this in the future.

[leadeater]

14 minutes ago, Syntaxvgm said:

Yah I'm aware of the loss. The consumer ones I'm looking at are 900w or more, and my load will not much exceed 300w on the battery side. I would intend to have the unit at the top be pure sine, or both really. Simulated sine does some weird things on some stuff that's not meant to run it, and who knows I may want change what I have on the end of this in the future.

Really comes down to if needs must then do it, just make sure you do a bit of research in to the UPSs you are going to buy and check their claim of being pure sine. There are UPSs out there that say on the spec sheet they are pure sine when in fact that aren't really true pure sine just "close enough to it".

 

Personally I'd get a used UPS without battery and buy a new battery pack for it, if the costs out better. Like this.

https://www.ebay.com/itm/EATON-PW9130L1500T-XL-1500VA-1350W-120V-BACKUP-UPS-103006428-6591-SMT1500-REF/222975264393?hash=item33ea5c8689:g:es4AAOSwoDFa9f59

 

https://www.ebay.com/itm/EATON-PW9130L1500R-XL2U-1500VA-1350W-Power-backup-UPS-103006449-6591-SMT1500RM2U/292559926835?hash=item441dee3633:g:1xwAAOSwd0ha9f58

 

https://www.ebay.com/itm/Eaton-PW9130N3000T-EBM-Extended-Battery-Module-UPS-Battery/222868949120?hash=item33e4064880:g:o0oAAOSwAO1ancVP

 

https://www.ebay.com/itm/Eaton-Powerware-Extended-Battery-Module-PW9130L2000R-XL2U/122833973844?hash=item1c9979b254:g:07cAAOSwHYpaHdRP

[8uhbbhu8]

@leadeater Hmm I've actually been considering something like this for a while too. Those links are helpful. Any idea how many of those rackmount modules you can chain?

[leadeater]

7 minutes ago, 8uhbbhu8 said:

@leadeater Hmm I've actually been considering something like this for a while too. Those links are helpful. Any idea how many of those rackmount modules you can chain?

4 EBMs can be connected to an Eaton 9130 (none for the 700va model though)

 

http://eg.eaton.com/ups-battery-runtime/en-us/PW9130G2000T-XL

[Syntaxvgm]

16 minutes ago, leadeater said:

Really comes down to if needs must then do it, just make sure you do a bit of research in to the UPSs you are going to buy and check their claim of being pure sine. There are UPSs out there that say on the spec sheet they are pure sine when in fact that aren't really true pure sine just "close enough to it".

 

Personally I'd get a used UPS without battery and buy a new battery pack for it, if the costs out better. Like this.

https://www.ebay.com/itm/EATON-PW9130L1500T-XL-1500VA-1350W-120V-BACKUP-UPS-103006428-6591-SMT1500-REF/222975264393?hash=item33ea5c8689:g:es4AAOSwoDFa9f59

 

https://www.ebay.com/itm/EATON-PW9130L1500R-XL2U-1500VA-1350W-Power-backup-UPS-103006449-6591-SMT1500RM2U/292559926835?hash=item441dee3633:g:1xwAAOSwd0ha9f58

 

https://www.ebay.com/itm/Eaton-PW9130N3000T-EBM-Extended-Battery-Module-UPS-Battery/222868949120?hash=item33e4064880:g:o0oAAOSwAO1ancVP

 

https://www.ebay.com/itm/Eaton-Powerware-Extended-Battery-Module-PW9130L2000R-XL2U/122833973844?hash=item1c9979b254:g:07cAAOSwHYpaHdRP

yah thats the other idea I was considering, though I didn't find cheap enough models I suppose. Nothing wrong with a used UPS. I'm pretty sure I've replaced batteries on UPSs that were 25+ years old before. 

Those are good links, didn't look into Eaton. I'll research them more when I have time and see what kinda costs I can come up with. I know it wont be cheaper than daisy chain idea, but if it's in a justifiable range then I'd rather do it, especially considering the expandability. 

[leadeater]

7 hours ago, Syntaxvgm said:

Those are good links, didn't look into Eaton. I'll research them more when I have time and see what kinda costs I can come up with. I know it wont be cheaper than daisy chain idea, but if it's in a justifiable range, then I I'd rather do it. 

The 9 series is rather high end, Online Double Conversion, you can get cheaper 5 and 3 series ones as well. 5 series is probably more in the area you are looking for. Eaton is my preferred UPS brand which you could probably tell by me linking them .

[8uhbbhu8]

On 5/17/2018 at 8:09 PM, leadeater said:

4 EBMs can be connected to an Eaton 9130 (none for the 700va model though)

 

http://eg.eaton.com/ups-battery-runtime/en-us/PW9130G2000T-XL

Hmm so with my current setup, leaving a good chunk of room for extras, I can get ~ 7h of runtime (on a full cap battery) with 4 EBMs. That's pretty damn good id say.

 

Thoughts on the noise level of these when they are running? I know most batteries get quite hot when discharging to a inverter for AC from DC.

[8uhbbhu8]

On 5/17/2018 at 8:12 PM, Syntaxvgm said:

yah thats the other idea I was considering, though I didn't find cheap enough models I suppose. Nothing wrong with a used UPS. I'm pretty sure I've replaced batteries on UPSs that were 25+ years old before. 

Those are good links, didn't look into Eaton. I'll research them more when I have time and see what kinda costs I can come up with. I know it wont be cheaper than daisy chain idea, but if it's in a justifiable range then I'd rather do it, especially considering the expandability. 

Wow 25 years is a long time.... Those must have been real dead or refilled (many times) sealed lead acid to have still worked.

[leadeater]

23 minutes ago, 8uhbbhu8 said:

Hmm so with my current setup, leaving a good chunk of room for extras, I can get ~ 7h of runtime (on a full cap battery) with 4 EBMs. That's pretty damn good id say.

 

Thoughts on the noise level of these when they are running? I know most batteries get quite hot when discharging to a inverter for AC from DC.

Depends on UPS type, Online Double Conversion (9 series and above) are always loud as the inverter is always running so it needs cooling. UPSs aren't designed to be quiet either so if noise is a problem then avoid Online Double Conversion (even though it's the only type I'd personally buy).

 

Inline and Switching are much quieter until running on battery then typically a little louder than Online Double Conversion as they are cheaper units and use cheaper inverters plus aren't always active so noise is even less considered.

 

Basically if you want quiet you need to get office/workstation optimized models or stay at/below 1000va.

 

The much less obvious option is to actually install a solar system controller and battery charger and just not use any solar panels at all, just mains AC charge the batteries and only get dedicated circuits wired to the solar inverter. Solar inverters are quieter and are housed in a more naturally ventilated unit and you can much more easily expand the battery bank. Just get it all installed in a garage and not even have to care. Without solar panels a solar system is just a switching UPS anyway.

[Syntaxvgm]

53 minutes ago, 8uhbbhu8 said:

Wow 25 years is a long time.... Those must have been real dead or refilled (many times) sealed lead acid to have still worked.

nah I mean the units not the batteries in them. Units that had worked a long time and just kept getting new batteries. 

[KarathKasun]

Build your own UPS.  Its fairly simple to do if you know wiring specs and battery charging/chemistry specifics.

[scottyseng]

6 hours ago, 8uhbbhu8 said:

Thoughts on the noise level of these when they are running? I know most batteries get quite hot when discharging to a inverter for AC from DC.

I have the rackmount 9130, it idles at around 38dB. It's not exactly quiet. Though at this point, we've gotten used to it being in my room and it even feels eerily quiet at my house if the UPS is off (usually when the power goes out for a long time). Also, you'll want to put a filter cloth on the front face, this UPS sucks in a fair amount of air / dust.

[dalekphalm]

On 5/17/2018 at 8:32 PM, Syntaxvgm said:

And you can daisy chain a power bar all you want, just loading appropriately so long as it's not exposed to people with the bright idea to plug more in. Do it for monitors and stuff all the time. Where a killawatt comes in handy. Typically try to use smaller ones or just splitting extensions so you can't plug more than I have in them. The warnings on surge protects are not about the surge suppression function interacting, but really just to prevent dumbasses overloading stuff, which they do, even on one strip.

For a home scenario, you can probably get away with that. And you're right, as long as you don't overload the wire gauge, you should be fine.

 

But, if this is for a business? I'd get rid of any daisy chaining ASAP. It's against fire code almost everywhere, and fire code violations can net you big fines, or they can even shut down your business in certain scenarios.

 

But again, I don't know the context of where you're doing this, so I'm just giving my opinion on trying to save you trouble, in case you didn't consider this aspect. It's nothing against you or your skill or your knowledge in hooking up equipment.

 

Anyway, as far as my research goes, it seems like yes, you probably can daisy chain multiple pure sine wave UPS's, but you're likely to have some pretty bad inefficiencies added into the system with each chained UPS. If you're just chaining two together, it likely won't be too bad. But it'll just get worse from there. I would consider that against the cost savings of getting UPS's that can add external battery packs. Look on the used market for the chassis if you're trying to find a good deal.

[Syntaxvgm]

4 hours ago, dalekphalm said:

For a home scenario, you can probably get away with that. And you're right, as long as you don't overload the wire gauge, you should be fine.

 

But, if this is for a business? I'd get rid of any daisy chaining ASAP. It's against fire code almost everywhere, and fire code violations can net you big fines, or they can even shut down your business in certain scenarios.

 

But again, I don't know the context of where you're doing this, so I'm just giving my opinion on trying to save you trouble, in case you didn't consider this aspect. It's nothing against you or your skill or your knowledge in hooking up equipment.

 

Anyway, as far as my research goes, it seems like yes, you probably can daisy chain multiple pure sine wave UPS's, but you're likely to have some pretty bad inefficiencies added into the system with each chained UPS. If you're just chaining two together, it likely won't be too bad. But it'll just get worse from there. I would consider that against the cost savings of getting UPS's that can add external battery packs. Look on the used market for the chassis if you're trying to find a good deal.

you're right about businesses, but let me tell you from experience most of them do it, and it's bad, especially with cubicles. You're looking at 20amp or sometimes I think 30 amp circuits, and they almost never add a ton of new capacity to their breaker and new lines. Nope, that's expensive, and IT cant justify the cost when "other businesses used the power in this building just fine.  "
They plug the cubicles in 2, 4, or more to circuit, and it all works fine with smarter employees. Then winter rolls around, and they have a no space heater rule. "Makes sense" thinks Becky. "they want to save power" but she's cold. After she blows the breaker or worse and more commonly melts her power strip, she's like "it was a small space heater though" and no matter ho much you explain ahead of time to these people, they simply refuse to understand that all 120v space heaters take the same amount of power- about 750w on low and 1500w on high. "But its small". 

There will always, without fail, be a space heater Becky. Unfortunately, as far as maintenance or IT goes, your power to do anything about the wiring is limited, and you just have to hope there's no fire and just melted power strips. 

Oh I've seen offices that implement a "bring it to IT first before plugging it in" rule and most people happily complied cause it's real easy- one look and they could tell you it's ok or to plug it in the break room instead. But not the Beckys, oh no. Surely her own coffee pot is ok. It just makes coffee, how much power can that take? Becky knows better. 

The only people that have access to my stuff both know better, and still ask where I'd like them to plug stuff in. 

[KarathKasun]

5 minutes ago, Syntaxvgm said:

*snip*

Becky knows better. 

This is why smaller offices are nice to work in.

 

Honestly, in a large office I would physically lock down any/all 120v outlets for safety.

[Syntaxvgm]

12 minutes ago, KarathKasun said:

This is why smaller offices are nice to work in.

 

Honestly, in a large office I would physically lock down any/all 120v outlets for safety.

a lot of cubicles have a couple of outlets, and you can limit it to that all you want- one for computer, 2 for monitors, one for phone, but Becky will just bring her own powerstrip. Best bet is to invest in something that will trip just at the cubicle itself, not down the line. But IT is always shackled by management. 
Ideally, the best policy is not to tell them "no space heaters" but to tell them "we prefer no space heaters, but if you must IT needs to plug it in" and just run these people a nice thick extension cord between the cubicles to a safe outlet. It's easier to tell people that than have a total ban. Its better to know about the fire hazards than have Becky hide her 1500w foot warmer under her desk. 

This is also why IT should both monitor power draw and also look around the cubicles every now and then. 

[dalekphalm]

Fortunately we have a Facilities department that handles electrical. We also have health and safety inspections (facilities always has one member attend) at least once a month. 

 

They are are very strict about those kinds of things. 

 

We also have a ton of circuits (and even the shared offices have only 5 people max in them), and management understands the cost of safety. If a new circuit is legitimately needed, they’ll pay to install one. 

[KarathKasun]

7 hours ago, Syntaxvgm said:

a lot of cubicles have a couple of outlets, and you can limit it to that all you want- one for computer, 2 for monitors, one for phone, but Becky will just bring her own powerstrip. Best bet is to invest in something that will trip just at the cubicle itself, not down the line. But IT is always shackled by management. 
Ideally, the best policy is not to tell them "no space heaters" but to tell them "we prefer no space heaters, but if you must IT needs to plug it in" and just run these people a nice thick extension cord between the cubicles to a safe outlet. It's easier to tell people that than have a total ban. Its better to know about the fire hazards than have Becky hide her 1500w foot warmer under her desk. 

This is also why IT should both monitor power draw and also look around the cubicles every now and then. 

You can physically lock down outlets, there are things for this.