How to estimate battery backup duration for CS1K/MRF-150/MPR-25 combo.

[Telecorn]

Hi there,

While the main purpose of our battery backups solution for our PBX is to keep it running while emergency power kicks in, I've been tasked with determining approximately how long the batteries will last in the event that no other power is available. I know there are a lot of factors to consider but I'm hoping some of you might be able to help me provide a reasonable estimation.

We have 2 shelves of 4 NPR-125 batteries each, one MRF-150 with 4 MPR-25 units. The connected CS1K is a former Opt 61C with 2 core/net shelves and 5 IPE shelves (2 of which are almost empty). This back up power solution is also connected to our old SL-1 system, on which I have shut off every breaker I can find, so it should be drawing next to no power.

Is this enough info to determine if I'm looking at 15 minutes, an hour, 4 hours, 8-10 hours of performance out of the batteries? Lets also assume for now that the batteries are in proper working order, I unfortunately don't know the age of the batteries, but no bulging/cracking/leaking is visible at this point. I do intend to have our maintenance provider test the batteries and replace them as required.

Thanks for any help/insight you can provide.

Mike

 

[Telecorn]

Oops, that should read NSB-125 batteries, like these:

http://www.northstarbattery.com/1.0.1.0/188/NSB125_SES-542-11-03.pdf

 

[hawks]

I'm not really sure but I have an 81c with 3 columns and the same MRF-150 with 12 batteries. I was told mine would hold power for at least 2 hours luckily I've never had to go that long. But I did lose power one time for 30 minutes and it did not skip a beat.

The following is from the Planning and Engineering Guide.

To determine the sizing and provisioning of UPS batteries, follow the instructions provided by the UPS manufacturer. A general approach is to take the total system power in watts, divide by the UPS inverter efficiency, and convert to battery current drain by dividing by the nominal discharge voltage of the battery string. Then determine the battery requirements in ampere-hours (A-hrs) by multiplying the battery current drain by the required reserve power operating time.

 

[KCFLHRC]

There are so many variables that it's really hard to say. Battery amps, battery size, and on and on. Is it a 12v, 6v, 2v batteries. I have seen it all. The 2v batteries typically have more amps but I typically see the 12v strings as opposed to the others. Age of the batteries has a lot to do with it also. 3 years or older and you are on borrowed time.