UPS switches off way before battery is empty

CathJ

CathJ

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I've noticed that my UPS seems to switch off exactly 2 hours after load shedding starts - and this has happened too often to be coincidence. And when I run UPS assistant as soon as power comes back on, it says the battery is 75% (or so) charged.

Is there a default switch-off time setting that I'm missing?

ETA: It's a RCT 650VA, if that makes any difference.
 
I'm not an expert on the topic, but a standard UPS doesn't have deep cycle batteries. This means that running them down too low will cause serious damage to the cells inside.

So 75% is likely as low as the charge level can drop safely and not cause significant deterioration of the cells inside.
 
It might help if you give more info on your ups. But your batteries could also be chronically under charged/degraded and thus the voltage is dropping below cut off point very rapidly.
 
Getting an echo in here.

2 hours exactly, hey? Been mentioned all over the forum in the past ~24 hours. My 650VA Mecer does the same. Busy investigating it. Hoping that it is a software setting somewhere.
 
If you find a solution, please post here - it's annoying spending the last 10 minutes of loadshedding in the dark, but what's more annoying is that when it switches off, it loses the "no beeping" setting and I have to go into UPS assistant every single time after loadshedding to switch the beeping off again!
 
I added another 2 x 7Ah external batteries to my old Mecer ME1000 but didn't make any difference in time to shut down.. I'm stumped :(
However, mine does keep the alarm setting after rebooting - settings attached
 

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  • settings.jpg
    settings.jpg
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Went through every single available setting via ViewPower and found nothing of interest. :-(

I still want to test the "10 second battery self check" option though, want to trigger that while the UPS is running to see if it influences the 2 hour runtime at all.
 
Interestingly, today when it switched off exactly 2 hours after loadshedding started, I switched it back on and it carried on running until the power came back on 10 minutes later.

Unfortunately because it switched off in between, it did the "beep every 30 seconds" thing. But it does strongly suggest there's a timer switch in there somewhere.
 
connect an inline volt meter and see what happens
cut off is normally at 10.5v on a 12v system
 
12v shutdown is too high
that will happen in minutes with a load connected

i cannot say why on other UPS models as i only use APC UPS's. You pay more but they are bulletproof and last forever.
I am very interested now to know why and looking forward to an answer
 
Papa Smurf said:
12v shutdown is too high
that will happen in minutes with a load connected

i cannot say why on other UPS models as i only use APC UPS's. You pay more but they are bulletproof and last forever.
I am very interested now to know why and looking forward to an answer
Click to expand...
10.5 is too low, I think the UPS is protecting the battery, 12V should be very close to 50% DoD, 10.5V is how you kill a lead acid.

It is a general not to discharge a lead acid below 50% dod, I think the UPS is doing exactly what it's supposed to do.
 
thechamp said:
10.5 is too low, I think the UPS is protecting the battery, 12V should be very close to 50% DoD, 10.5V is how you kill a lead acid.

It is a general not to discharge a lead acid below 50% dod, I think the UPS is doing exactly what it's supposed to do.
Click to expand...
interesting
my UPS's shutdown at 10.5v which is 0% of lead acid battery.
 
75% is a safe discharge level for lead-acid batteries. Lower than this and they will soon be ruined
 
It is 2 hours. Exactly 2 hours. 120 minutes.

There is no way in hell that the battery cutoff percentage happens to occur exactly on the 2 hour mark. My 18ah 12V battery bank is currently at 13.73V and I have just pulled the plug. Timer is running. Will report back. I just hope my TV does not pull too much.

12 minutes in, 12.70V. I lowered the brightness on the TV at this stage.

To rule out heat, I have opened up the UPS and have positioned a USB fan to blow out the hot air.

30 minutes in, 12.65V.
76 minutes in, 12.33V.

Died at basically 1 hour 58 minutes xx seconds. Voltage was at 12.30V at that stage. Restored to 12.44V.

Will repeat the test. It should die at the same point again.
 
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If the UPS switches off after running X minutes regardless of load then it has an internal timer which is controlling the run time.
If the UPS management software doesn't expose the timer settings then there's not much one can do unless you're an electronics engineer and modify the circuitry or reverse engineer and reflash the firmware.
 
ld13 said:
It is 2 hours. Exactly 2 hours. 120 minutes.

There is no way in hell that the battery cutoff percentage happens to occur exactly on the 2 hour mark. My 18ah 12V battery bank is currently at 13.73V and I have just pulled the plug. Timer is running. Will report back. I just hope my TV does not pull too much.

12 minutes in, 12.70V. I lowered the brightness on the TV at this stage.

To rule out heat, I have opened up the UPS and have positioned a USB fan to blow out the hot air.

30 minutes in, 12.65V.
76 minutes in, 12.33V.

Died at basically 1 hour 58 minutes xx seconds. Voltage was at 12.30V at that stage. Restored to 12.44V.

Will repeat the test. It should die at the same point again.
Click to expand...
That's a very decent run time from an 18ah battery, one advantage the UPS have over the normal inverters is the efficiency as well as noise levels, I miss mine, it was way more efficient than the Ellies inverter I am currently using.
 
i am very impressed by that 18aH battery lasting 2hrs on a load :thumbsup:
 
Can someone contact mustek and confirm this 2 hour limit


I am about to order, but would rather go APC if meecer/mustek has a time restraint on their UPS, seems. Absurd.
 
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