UPS/Inverter recommendation for 750-850W PC

enthusiast29 said:
Moti party ho aap Sir. Anyways, did you try full stress testing the PC and then simulating power cut?
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msedcl does that for me every now and then :p I get so much fluctuation that I hard to call inverter guy to check the inverter and he told, SOLID he iska performance, its the msedcl issue, not your inverter and all. and I am using pc and ac together all the time. like 12 to 16 hrs daily.
 
Bought APC 1100VA UPS for 6300 INR locally. Issue resolved. Full stress tested the PC and removed input power from UPS and it switched fast enough.

To be tested:
Backup time on normal load and full load.
Connecting inverter output to UPS input and simulating power cut while PC on full load. I need to check does it trip the inverter or not.
 
enthusiast29 said:
Bought APC 1100VA UPS for 6300 INR locally. Issue resolved. Full stress tested the PC and removed input power from UPS and it switched fast enough.

To be tested:
Backup time on normal load and full load.
Connecting inverter output to UPS input and simulating power cut while PC on full load. I need to check does it trip the inverter or not.
Click to expand...
Do let us know of your test results.

I'm interested in 2nd case for future purposes.
 
This is what I found.

You can use a home inverter as UPS for the desktop computer, only if your home inverter has offline UPS mode [sometimes also marked as UPS mode]. Many home inverters have come with ECO and offline UPS modes. And when the home inverter is on offline UPS mode its switching time becomes less than 5 milliseconds (ms) and modern computers can tolerate a delay of 5 ms.

I know luminous have this mode.
 
@Heisen
5ms is a lot less and I have serious doubt inverters have a switching time of 5ms because even dedicated line interactive UPS advertise switching time of 6-12ms max.
As per my knowledge and research all UPS mode in inverters does is narrows down the input voltage range to switch to battery sooner (not faster, there's a difference).

Typically inverters switch to battery mode when voltage reaches outside 85 - 290 V level. Now this range is quite large and this means even if your input voltage drops to 100 V your inverter will not switch to battery just yet.
Now when UPS mode is enabled this range is narrowed to around 180 - 265 V. Now as soon as your voltage drops below 180V your inverter with switch to battery even if it's a momentary spike.
I'm speaking practically here as I've tested these scenarios and on Luminous inverter.
 
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Any reason why you are not considering APC BR1500G + external battery pack? I am pretty sure that that beast can handle any gaming PC you throw at it.
 
rahuljawale said:
Any reason why you are not considering APC BR1500G + external battery pack? I am pretty sure that that beast can handle any gaming PC you throw at it.
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Budget + abysmal backup on almost any home UPS.

BR1500G costs 250% more than BX1100C. It makes no sense when I have an inverter to provide external backup to UPS.
 
Wow! I did not realise that you are planning to power UPS through inverter. That is a lot of conversion losses there, AC -> DC (Inverter battery) -> AC (UPS) -> DC (UPS battery) -> AC (PC) -> DC (onboard components).

My recommendation would be to go for a bigger inverter because,
1. you cut the middle man (UPS) out.
2. save on some of the conversion losses
3. get longer backup for the whole house when you are not running PC
4. inverter batteries are easier to maintain (water top up etc) and live longer.

I have used Amaron Tribal inverters in the past and not once did it fail my PC. It has UPS and Regular switch at the back, which reduces the switch over time to 5-8ms. I am now using Luminous ICON and it too can handle my PC well. So before you buy, check the manual for UPS mode and UPS mode switch over response time.
 
That is a lot of conversion losses there, AC -> DC (Inverter battery) -> AC (UPS) -> DC (UPS battery) -> AC (PC) -> DC (onboard components).
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@rahuljawale I don't think that's true when AC power is present. The inverter/UPS will bypass the battery and supply AC directly to the connected appliance.
As for when there's no power, again inverter will supply from battery to UPS, UPS will bypass its own battery and supply to PC because in view of UPS the power is present.
While battery charging it's what it is... since it's converting energy it is understood some will be lost as heat.

I agree with other points for sure but the thing is power outage is not my main concern here as they are minimal to none. The problem here is since past 2-3 months we're getting a lot of voltage surges and power fluctuations.
When my PC was on load and any of the above happens it just trips my inverter into overload state probably due to less capacity (900VA), PC power usage is 400-450W (approx.) from wall. It's fine when idle or CPU load is there but it can't handle GPU load. I also tried just the PC on inverter and nothing else, but nope...

Anyways, I did think of increasing inverter capacity but the investment amount is really high (at least 30-35K or more for inverter + 2x batteries) and there was no guarantee of switching time being optimal. Dealers here won't take it back if it doesn't serve my purpose.
As I don't need the backup for anything more than 5-10 mins the UPS way is cost effective to me and pretty much guaranteed optimal switching time.

Hence I did buy the APC BX1100C a couple days ago and the problem is solved. I will not keep it plugged to the inverter but to the mains directly. If power cut happens and it's is a bit longer (which happens very rarely, I can't even recall the last time it happened), I will switch the input from mains to inverter for the UPS after I reduce or remove the load on the PC.

To others,
enthusiast29 said:
To be tested:
Backup time on normal load and full load.
Connecting inverter output to UPS input and simulating power cut while PC on full load. I need to check does it trip the inverter or not.
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Got a chance today...
Backup on normal load is around 30 mins and on full stress load is 2-3 mins.
The inverter still trips and goes down. I will keep the UPS plugged into the mains, if power goes out for longer than expected (very rare) I will have to manually switch the UPS input power from mains to inverter after reducing load on PC or putting it to sleep mode.
 
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enthusiast29 said:
Perhaps but then what puzzles me is that why the inverter is able to handle full stress load of PC when already running on battery?
It's just not able to handle when it's switching.
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This is precisely the difference between an Inverter and a UPS: the power is Uninterrupted in the latter, which is the main requirement for PCs, whereas for powering a home, it isn't a problem if the lights flicker when mains is cut and batteries come online. In fact, that might actually be useful to let you know that the power is cut.

Home UPS is a misnomer for Inverters. They are not UPS unless the switching happens fast enough that PCs don't reboot.

Like mentioned before the Eco/UPS mode on Home Inverters may or may not mean suitable for PC usage.
  • Eco = Line Interactive mode, where the batteries are charged as required, but the inverter is OFF and turns on only when there's a power cut
  • UPS mode = the inverter is always on, like in Online UPS. This is helpful in case of voltage fluctuations. The batteries get charged, and the inverter uses battery power to power your devices. Since there is double conversion from AC Mains > DC battery > AC output, there is a bit of loss which will show up on your electricity bill and reduce the battery life a bit. The advantage here is that there is no switching delay since the inverter is always on anyway
 
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@n1r0 I'm aware and almost fully confirmed that this is a switching time issue. Please read a few of my earlier posts.
I have even tried UPS mode on my inverter and that's not what it means. UPS mode just narrows the voltage range where the switch to battery will happen.

Online UPS are way too expensive for my purpose and not practical to use at home.

Maybe I didn't phrase my question properly, what puzzles me is, why does the inverter shows overload status and turns off the battery supply when switching on full PC load? It doesn't do that when it's already running on battery.

Does it need to be a higher capacity only when switching?
Or is this behavior same when switching time is higher and load is high so if the load is dropped suddenly due to higher switching time inverter senses a false overload scenario?
 
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I did, but you said you were still puzzled, so my previous reply :sweatsmile:

I think a Home Inverter w/ big batteries + a PC UPS combo should suffice. If you need to extend PC usage time connect the UPS to inverter. Else, leave it connected to mains so that PC UPS will not feed off of Home Inverter batteries to stay charged.
 
@enthusiast29 so when you were running tests, did you have any other loads apart from PC running, like Fan(s) or Tubelight(s)? Most home inverters are rated to deliver 6A at 220/240V since that the size of the fuse I have seen installed in most 800/850/900VA inverters.
 
@rahuljawale I did mention in my previous replies. I tested both scenarios. Same result. Inverter shows overload and stops the output when switching on load.
Works fine when PC is on full load but inverter already on battery.
 
Although for now I've found a solution but still wanna keep updating here as I get more knowledge on the issue.

There's something called "jerk load" (sounds so wrong lol). This is the power/current drawn by appliances when there's a sudden interruption in power (like during switching from mains to battery). These appliances will try to stay on by drawing more power than usual during interruption. For the inverter to support this scenario it must be rated at least 25-30% more than your actual power needs. If the inverter isn't rated that much then it'll trip and show overload condition.

I'm guessing this is what is happening to me in addition to the switching time not being enough for my PSU. Switching time needs to be less than 15ms for stress load but inverter takes 20ms. So even if I had a higher capacity inverter I would be in the same situation of my PC getting restarted when on load and power cuts, only benefit that inverter won't show overload.

I might get higher capacity inverter later this year or next year. Not really needed now.
 
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