[SOLVED] Ok to run Pc off of back up generator

[Dogsnapper6]

Hello I have been hit by a few storms that my community has lost power for days from one just happened last night and I’m still without power so I have a Generac 20,000 Watt home standby backup generator that runs off natural gas and I’m wondering if it’s safe to run a gaming Pc with it if it normally is then I have another question of will a standard APC ups battery backup work not the AVR model though and if my back up gen sometimes stutters and the lights dim a few times a day is it still safe to use? Thanks so much in advance.

 

[Aeacus]

Generac 20,000 Watt home standby backup generator

That thing produces square wave output waveform and isn't suited at all for the very sensitive PC's PSU. Better generators produce simulated sine wave output waveform and is better suited running home appliances. However, not all PSUs can handle simulated sine wave either. PSUs with Active PFC will have issues with simulated sine wave. For powering the PC, what you'd need is true/pure sine wave output waveform. Consult your generator manual to see what kind of output waveform it produces. Though, i'm quite sure it doesn't produce true/pure sine wave.

will a standard APC ups battery backup work

It works, given that the APC UPS also outputs true/pure sine wave. Though, most APC UPS'es produce simulated sine wave and many Active PFC PSUs are picky about that.

Some Q&A:

How do you know which PSUs have Active PFC and which ones don't?
Simple, every PSU that has 80+ certification (e.g 80+ Bronze or 80+ Gold) has Active PFC.

What is Active PFC?
Further reading: https://en.wikipedia.org/wiki/Power_factor#Power_factor_correction_(PFC)_in_non-linear_loads

What can happen when using simulated sine wave UPS with Active PFC PSU?
When simulated sine wave UPS switches over to the battery power, one of 3 things can happen:

1. UPS displays error resulting PC to shut down immediately.
2. UPS shuts down resulting PC to shut down immediately.
3. UPS switches to battery power resulting PC to power off from UPS (PC stays on).

Why it happens?
Simulated sine wave UPS produces a zero output state during the phase change cycle resulting in a power “gap”. This gap may cause power interruption for active PFC PSUs when switching from AC power output to simulated sine wave output (battery mode).

What to do next?
As stated above, your PC can run off from simulated sine wave UPS but be prepared when you face issues with it. When issues do rise, your best bet would be returning the simulated sine wave UPS and getting true/pure sine wave UPS. Or you can go with true/pure sine wave UPS off the bat.

Also, do note that consumer grade UPSes aren't designed to run your PC 24/7 by constantly draining it's battery power while in the same time, recharging it. Consumer UPSes (stand-by design and line-interactive design) are for emergencies, when the main power cuts off and your PC is still running, so that there is no damage to your PC during power cut, where you can safely turn off your PC.
Enterprise grade UPSes (online design, aka double-conversion topology) are designed exactly like that where server is constantly running off from UPS'es battery power while in the same time, the battery is recharged. This design is top-of-the-line in UPS world and also costs a fortune.

if my back up gen sometimes stutters and the lights dim a few times a day is it still safe to use?

You'll burn out your PSU with this. Since it takes less than a quarter of a second of power loss for PSU to loose power and hard shutting down the PC, possibly causing data corruption on your storage drives.

By ATX PSU standard, PSU must be able to keep the PC running for 17 milliseconds (0.017 seconds) when power is cut off. Best PSUs in the world can keep the PC running for 30 milliseconds. That isn't much time at all. And due to that, it's best when PSU is backed up by UPS.

Also, lights dimming = brownout (voltage drop). PSUs have some form of AVR in them but it's scope is very small and the visible dimming of lights that you can see is a lot lower voltage drop than PSU is capable of handling. Due to that, it's best when there is AVR before the PSU or even better, an UPS (since AVR is built-in to the UPS).

In an off-grid area, where there is no main power line, the are two methods to run PC:

1. Generator -> AVR (outputting true/pure sine wave) -> PSU.
2. Generator -> Line-interactive UPS (outputting true/pure sine wave) or online UPS -> PSU.

1st case is cheaper but when generator runs out of fuel, your PC will be shut down instantly, possibly causing data corruption, not to mention loosing all unsaved work.
2nd case is more expensive but in the event when your generator runs out of fuel, you have some time (UPS battery capacity) to either restart your generator or shut down PC safely.