What determines the shut down ?

[Anonymous user]

I have a Back-UPS XS 1300, and I have  larger capacity batteries then came with this unit.  What determines the shut down, does it assumes it has two 9ah batteries, and looks at the time factor, or does it look at battery voltage ?

The software does not provide any way to adjust for longer battery time.

Also on a side note, it is very annoying that this unit has a known problem with LCD dimming, and even in the dark, very difficult to read.  It would be nice if such a part was available, so I could replace, and yes I'm Tech.

I have no other complaints about these units, other then replacing batteries, and the dim LCD, they have been working fine, I have two of these units.

Roy

[BillP]

Hello Roy,

I inquired about the runtime and was told that the UPS calculates runtime based on the capacity of it and the rate of discharge in relation to the AH of the original battery. Back UPS are not too flexible as allowing the user to add external, third party battery packs in like some of the larger UPS models are unfortunately. We only had a few models that supported their own APC external battery packs that I know of. I think even those only supported two because then the internal UPS charger can't keep up which is another concern of adding your own external batteries since the UPS charger is sized for the original battery size.

As for the LCD, it seems as though there was a firmware adjustment at some point to extend the life of the LCD and likely dim it a little bit to help it last a little longer overall. While you may be experienced with replacing the LCD, the smaller UPSs usually don't have serviceable parts like this (outside of the battery module) because majority of the install base is not experienced with this type of replacement and I am sure the company won't want to be liable for people doing this and damaging something or hurting themselves. I imagine the cost of making the part safe to replace for all users is not worth it for a smaller UPS but I am just making an educated guess on that comment along with my personal opinion.

[Anonymous user]

Thanks for the info, I kind of knew that it was the way it determined the run time, I was just hoping.  The question is now, how does it reset ?

Does it reset when line voltage is reapplied, and does it look at its charging time to know what amp hours are available for the next time.  I have two 100ah AGM batteries connected, they were left over from an another project, I tested the charging voltage and it's right on the button. 

I realize that APC does not want to deal with people repairing their own stuff, but I'm a 70 old technician and have been repairing electronic stuff most of my adult life.  Its a shame that such activity is no longer encouraged, for there is a lot to learn with such activity, I guess I'm getting up in age, and don't like to accept we have become a buy and throw away society.

Roy

[BillP]

Hi Roy,

I'll have to check into it further. The person I want to ask that may know has left for the day so I'll report back on Monday I hope. I am not sure how it resets specifically.

I agree what you said in your last paragraph. It is kind of sad

[BillP · Accepted solution]

Hi again Roy,

After checking and trying to better understand this myself to explain to you, the most accurate runtime will be seen when the UPS is on inverter supplying power to the attached load. This runtime is dynamic and adjusts as load is added or reduced, in relation to the preset battery constants in the UPS EEPROM. This constant is set at the factory for the battery being shipped with the UPS and can not be altered in the field. The constant adjusts over time, as the battery discharges and recharges in an effort to provide the most accurate runtime. The only other option which we don't know if it will work or not for what you need will be a runtime calibration. If anything, I suspect there is a maximum runtime the UPS will report based on a brand new battery (referring to the included 9AH battery) and if anything, it could report that max value to you at least based on a full capacity 9AH battery.