UPS problems and battery questions

[slicksilver]

I have a APC SUA1000UXI UPS at my home for my desktop computer. I have two external batteries connected to them each 65AH. I currently live in India and power cuts are very common to us.

The only items connected to the UPS are my monitor and my tower. My monitor is a 27" Acer and is rated at 40W power consumption. My tower has a 350W cooler master supply and is powered by an Intel Quad Core Q6600 processor. It also has 4 GB RAM and a 128GB SSD.

EDIT > I just put my config in the calculator located here - eXtreme Power Supply Calculator Lite, http://www.extreme.outervision.com/PSUEngine and it showed me that it recommended a PSU wattage of 182W.

Two questions :

1. How many hours should it take for the UPS to charge the batteries from a near dead or discharged state?
2. Also with the above setup, how many hours of battery life should I be expecting?

My backup times are abysmal. I'm getting less than an hour of backup.

Thanks

 

[Red Squirrel]

Not sure how long it should take to charge, depends how the charger works, if it is always float or if it has different stages to speed it up. If you have a way to monitor the charging current you could figure it out with the amp hour rating and add 20%.... I think that would at least give a ballpark figure but I may be wrong, I'm no expert.

As for run time, assuming it is a 12V system and 130 total AH, you are pulling 16 amps at 182w so that should give you roughly 8 hours. AH rating actually goes down as the amps go up, meaning that a battery rated at 100AH might actually only be 50AH when a certain number of amps are being pulled. I think AH rating is usually rated at 40 amps or maybe it's 20, I forget so I think it's safe to use 130 as the actual rating when calculating for your case. I would guess about 8 hours then take away any efficiency in the conversion process and 6 hours is closer to what you'll actually get. I have a 200AH UPS with a load of around 350w and I get about 4-5 hours so seems it would make sense you'd get about 6 give or take with your load.

Put a volt meter on the batteries and monitor the voltage. It should start at 13.5ish then go down to maybe 12.7 and sit there for an hour or so and slowly start going towards 12. 12 is your midway point. Once you hit 11.3 or so you want to consider shutting it down to save the batteries. Realisticly you can probably get away with like 10v but I'd try to avoid that. With telco COs we tend to start looking at dispatching a generator when the voltage hits 48-47. I've seen cell sites go down to 44 volts, but that's something we try to avoid.

Given this is an APC UPS I would imagine it's designed smart enough to handle this right though....

Maybe your battery is degraded, is it older?

 

[slicksilver]

Not sure how long it should take to charge, depends how the charger works, if it is always float or if it has different stages to speed it up. If you have a way to monitor the charging current you could figure it out with the amp hour rating and add 20%.... I think that would at least give a ballpark figure but I may be wrong, I'm no expert.

As for run time, assuming it is a 12V system and 130 total AH, you are pulling 16 amps at 182w so that should give you roughly 8 hours. AH rating actually goes down as the amps go up, meaning that a battery rated at 100AH might actually only be 50AH when a certain number of amps are being pulled. I think AH rating is usually rated at 40 amps or maybe it's 20, I forget so I think it's safe to use 130 as the actual rating when calculating for your case. I would guess about 8 hours then take away any efficiency in the conversion process and 6 hours is closer to what you'll actually get. I have a 200AH UPS with a load of around 350w and I get about 4-5 hours so seems it would make sense you'd get about 6 give or take with your load.

Put a volt meter on the batteries and monitor the voltage. It should start at 13.5ish then go down to maybe 12.7 and sit there for an hour or so and slowly start going towards 12. 12 is your midway point. Once you hit 11.3 or so you want to consider shutting it down to save the batteries. Realisticly you can probably get away with like 10v but I'd try to avoid that. With telco COs we tend to start looking at dispatching a generator when the voltage hits 48-47. I've seen cell sites go down to 44 volts, but that's something we try to avoid.

Given this is an APC UPS I would imagine it's designed smart enough to handle this right though....

Maybe your battery is degraded, is it older?

5 hrs is what I got for the first 4 months. Its been barely 6 months since I got the batteries. Now I'm getting less than an hour. The battery company says its fine and the UPS company says their product is fine and I cant get either to solve the problem. I must mention to you that I'm in India.

I will buy a multimeter and check the voltage and report back to you. There is something seriously wrong and I want to see what I can do before I again talk to them.

Today I removed all load from the UPS. Left the batteries connected to the UPS on power for 12 hours with no load. When I switched off the power, the batteries didn't last for even 30 mins.

 

[Nec_V20]

Your battery will need something called "reconditioning" if they are used and discharged frequently. You have to make sure that your battery charger has this function othewise your battery performance will be continue to suffer.

Personally I have a 110Ah deep discharge gel battery for emergencies to use with my APC UPS.

 

[slicksilver]

Internal charger is capable of charging 24 V battery and delivering 15 A maximum charging current. The internal battery chargers operate in a constant current/constant voltage
charging mode.

The above is taken from the manual if this helps. I dont have a volt meter with me and today is Sunday. I'll get one tomorrow and report back.

 

[slicksilver]

Put a volt meter on the batteries and monitor the voltage. It should start at 13.5ish then go down to maybe 12.7 and sit there for an hour or so and slowly start going towards 12. 12 is your midway point. Once you hit 11.3 or so you want to consider shutting it down to save the batteries. Realisticly you can probably get away with like 10v but I'd try to avoid that. With telco COs we tend to start looking at dispatching a generator when the voltage hits 48-47. I've seen cell sites go down to 44 volts, but that's something we try to avoid.

Should this be done with load connected or without? Should the power be connected to the wall socket while checking the readings? Thanks.

 

[Red Squirrel]

Hmm do these get cycled very often? Gel cells arn't great for that because you can't add water to them (well you can but it's more complicated).

I guess you don't want to spend any more money if you just bought this, but if you have any plans for another one for something else, I would recommend an inverter-charger, like this:

http://www.tripplite.com/en/products/power-inverters-chargers.cfm

With some flooded lead acid batteries. Check the batteries every couple months and add distilled water as needed. This allows them to last longer.

For the load test I'd test it with the load, and unplug it to monitor voltage while it is running. Voltage should go down. It sounds like it's a 24 volt system, so just times everything I said by 2. So float voltage should be around 26v and the half way point will be 24v. You can test while charging too, as it will give you an idea if it's doing anything weird. 15a is not that much charging current, but enough for what you have, so I'd be surprised if it's overcharging it, but if the voltage is too high I suppose it could.

I suppose it's also possible your battery is just defective. Get two 12v Marine/RV batteries if you can just to test it out.

 

[webmaster1]

Hello,
I have exactly same configuration as you said but my UPS is from iball it keeps my PC on for at least 45minutes...()

 

[slicksilver]

My APC SmartUps 1000 contains (2) 12v batteries. The voltage across the pair of batteries when charging is 24V while plugged into the socket. Does this mean the charger is not working properly in the UPS?

EDIT> Thanks for your help RedSquirrel. Tripplite is not available in India.

 

[Red Squirrel]

Yeah 24 is kinda low for charging, did you test it for a long time, it might have not been charging at that point as it sensed the batteries were fully charged. Though typically it should at very least keep a float charge. Float is 2.25v per cell (this can vary though) and a 12v battery has 6 cells so that should be 27v. It's ok if it goes higher as long as it does not always stay there. Some "smart chargers" will increase voltage to charge faster then slowly decrease it. It does this in a way that is suppose to be safe for the battery.

 

[aigomorla]

hey RS i thought it was not safe to fast charge AGM's..

cuz of the fact they are sealed and quick charging them can cause them to blow up?

 

[Red Squirrel]

Yeah now that I think of it I don't think it's a good idea to do it, but pretty sure the APCs do it anyway. The voltage test would indicate that. Float is really the best way, even for flooded. I'm no battery expert though, I just know enough to be dangerous. :biggrin:

 

[slicksilver]

Batteries are working fine. The software(Powerchute) of the UPS was acting up and causing the shutdown and other problems. Remove the USB cable from the comp and all is well. Batteries when fully charged and connected to the wall outlet were showing 27.78V together. Got about 7.25 hours backup from start to finish.

Thanks all