UPS Problem

[edy252]

hi all

I have a 500 VA ups that is really important for my computer because we have lots of power failures.

I've recently changed it's batteries because they weren't holding any charge. I got home, plugged the computer (P4 + CRT monitor) to the ups, unplugged the ups, and all worked fine.

Few hours later, when there was a power failure, the computer restarted. I tested it again later, by unplugging the ups with monitor still on, and all worked fine!!!

so i'm really confused by what exactly is the problem?

Would a bigger ups help?..i wouldnt really want to spend my money on something that i wouldp really need.

ADVICES APPRECIATED.

[Chagrin]

Sounds like you might've experienced the difference between standby and on-line UPS systems. The former needs to switch the inverter on whenever there's a power outage and can be a bit iffy at times.

[Bruce S]

edy252-

   Could be a couple things.

When you first tried it after replacing the batteries and it worked fine those batteries more than likely had a really full charge on them.

Did you let it sit unplugged for more than a few seconds?

Also what about which outlets did you plug into? Most 500VA UPS's have plugs that are setup for non-critical items like printers.

If you received or have the software and a serial port on the UPS , set it up and do a load & uptime test on it. This will tell you if you have too much load on it( don't think so since it held the first time).

It could have been that the batteries merely did not have enough of a deep current charge on them and lasted the first time but didn't have the strength to hold up to another.

Most replacement batteries come with only a small surface charge and then they could've been sitting on the shelf for awhile too.

I generally don't put a load on a UPS after replacing batteries until it's had them in and it turned on for 24hrs. This gives the system a chance to equalize and deep charge the battery(ies).

Hope this helps

Bruce S  

[scottsAI]

Edy252,

Several things could be the root cause.

1. Most of my 9 usp's are rated to switch in 4 ms, the PC should work for that time without power. I have two ups that behaves like yours, I stopped using it for PC. I use it for the cordless phone. Not much good for a PC.
   
2. The PC power supply should have a reserve or hold time. Should be rated for 16-17ms. This means power can be missing for this time and the PS will keep the PC working. The power fail reset signal from the PS should be delayed, by that time. IF it occurs too soon, the power could be ok and yet PC is reset.
   
3. Dos the PC reboot or Locked up at any other time? If it does the ATX power supply may be failing. With windows it's hard to tell if it's a hardware or software issue.
   
4. If the PC has been sitting for a few hours, then the monitor is most likely shut down. Have you tried to start the monitor while on the UPS. Warning, most monitors run a degaussing cycle when starting up (make a humming noise). The startup power is much higher than the running current. I fired a computer when this happened. The monitor and PC were on the same ups. The power failed. I wiggled the mouse to wake up the computer with the intention of shutting it down. The monitor starting over powered the ups, the ups shutdown, then restarted, the monitor tried to start up again this cycle occurred several times before I could rip the power cord out of the PC. Should have reached for the monitor cord. The PC no longer worked. The mother board was fried.
   
5. All my monitors have their own ups. I get 300w ups on sale for $10 or so. Replacement batteries cost more than getting a ups on sale. My largest ups is 3kw, I plan to replace several smaller ups. I will keep the monitors on a different ups.
   
6. Looking at the post just before I replied, I agree with Bruce S, give the battery some time to get fully charged. Then retest.
   
   

Have fun.

[Bruce S]

ScottsAI:

   Good point #4. Forgot that part

I use the old minuteman 200pro just for the monitors. They're good for about 10mins uptime even with a 21" tube type; lus they have the ability to cold start if the AC is already out.

I did cheat with the ones at home, I opened up the side where the battery is, drilled a couple holes, added red & black adapters and added more batteries to get a longer up time.

These aren't real good for computers though, they use a modified sine-wave and not effiecient enough to use coming off a 300 watt FREE invertor.

Happy Charging;

Bruce S

[nothing to lose]

I agree with the other guys about both the monitor and batteries charge, and a combintation of both week batteries and monitor starting is even worse.

Whenever I buy a new UPS I plug it into the wall and leave it about 24hrs so the batteries can become fully charged before I ever connect anything to it. It may not take that long but most UPS's I think are a slow charge rate so how long does it really take to reach full charge with a 20amphr battery?? 20 hrs if 1 amp charging 10hrs for 2amps?? 24hours I figure should be enough to be certain of full charge, what ever rate it is. Or if you have the UPS manual read it and see if it says what the charge rate should be.

Batteries have a self discharge too, so even if they were supposed to be charged and ready to use when bought, they probably were not full charged. Depends how long they sat after being charged how low they could have been.

When cold starting (UPS power without grid power) I always start the monitor first then computer and other stuff. Monitor as stated noprmally has a much larger power draw when first turned on than in use. But with a power failure and both already on it should not matter really. Not sure about the surge when comming out of a sleep mode but already powered on, I don't think it's much.

[Dreadstar]

500va is only about 300watts. Calculate the max draw of everything plugged into the outlets on the UPS that are battery backed up. Some ups systems have outlets that are not protected. Large monitors can exceed the max power your UPS can supply during power on degauss and can damage the UPS or any device plugged into it.

And the only ups i buy use and recommend are online. These are always on units dual conversion AC in is converted to DC float charge on the batteries then rectifies to ac out and in the event of a  power failure these type UPS does not switch so there is no spike or loss of power at all.

Liebert 1500gxt These are 1000 watt units and are very nice and can be upgraded for some insane uptime. They run on a 48vdc system.Just be aware that 144ah is the max they can charge to. I have seen them for as little as $25 used on ebay. with a simple modification you can hook 4 35ah batteries up to them external this is much cheaper than buying the 2 external battery cabinets and the 20 7.2ah batteries required for them.

I highly recommend using 2 thermal take smart fan II 80mm thermal fans in them as the supplied 80mm fans are very loud and .3 amps each power draw. with the thermal take fans these units draw less than 30watts with no load attached. and the 4 internal 7.2ah batteries on float.

Lastly always buy a ups that has atleast 20% more power than the max draw of your components. This helps minimize the heat they generate when supplying ac power in the event of a power outage. It also helps the recovery time afterwards.

The lieberts will also run off of a modifed sine wave inverter and supply a fairly clean sine wave with this noisy power in.