Connecting two UPS to each other?

[her209]

How long could they stay powered on?



EDIT: Here's another question: if the two UPS units had different backup capacities, would they still go out at the same time?

 

[Jeff7]

Until one pees on the lawn.

 

[Miramonti]

/edit: I see what you did there.

 

[KK]

42 minutes

 

[Rubycon]

Plug the power strip into itself and enjoy free power anywhere forever.

 

[her209]

Here's another question: if the two UPS units had different backup capacities, would they still go out at the same time?

 

[Miramonti]

Here's another question: if the two UPS units had different backup capacities, would they still go out at the same time?

Depends what time the power goes off.

 

[SunnyD]

Depends on the inherent loss in the inverter/rectifiers no? I mean you even get loss just from the wire in the cables... so if you're thinking they'll last forever... well duh.

 

[Sasiki]

The 1st one should supply the 2nd one with 120v power until it runs out. Then the 2nd one would detect no power after the 1st one shut down. It would then switch to battery power.

 

[Modelworks]

Connect a motor to a generator and free power forever !

 

[her209]

The 1st one should supply the 2nd one with 120v power until it runs out. Then the 2nd one would detect no power after the 1st one shut down. It would then switch to battery power.

Would it?

 

[Rubycon]

Would it?

Not likely. First of all connecting UPS' in series is discouraged. Surge strips with LC filtering should not be connected to the output of a UPS as well. The exception would be true sine wave output UPS products. Others are stepped approximation to sine wave and that's where the problems start.

The downstream UPS is likely to stay on battery even though the first UPS inverter is supplying power. The watchdog monitoring power will treat the non sinusoidal waveform as rogue power and to maintain protection will turn its own inverter on. Additionally any hash filtering (LC) on UPS number two will produce an un-necessary load on its inverter!

If you have two identical model UPS' side by side (parallel) powering a resistive dummy load the runtimes won't be identical due to electronic tolerances and (most of all) SLA tolerances and overall health. SLA state is not tightly monitored on consumer grade UPS products. The chief purpose is to provide a means for you to save work when the power flickers or goes out from an interruption caused by a plethora of possibilities.

 

[westom]

Would it?

The power output from the first UPS in battery backup mode is typically so 'dirty' that the second UPS trips into battery backup mode. Then the second UPS runs down its battery and cuts off power to the computer.

That is the technical reason. Others have said same without saying why.

Appreciate that UPS in battery backup mode outputssome of the 'dirtiest' electricity a computer will see. Why? Because computers are so robust as to consider 'dirtiest' electricity as perfectly ideal. Do not connect small electric motors or power strip protectors to a UPS. 'Dirty' UPS power can harm those 'less robust' devices.