Trying to choose an APC UPS - Have some questions

[farkhispe]

I have spent forever researching APC UPS's, and I have it narrowed down to 3 different models

• SUA1500RM2U - Older 1500VA 2u Rackmount Smart UPS

• SMT1500RM2U - Newer of the above

• SMT1000RM2U - 1000VA of the above

For either of the 3, I will be using AP9630 or AP9631 network cards. I only have a 200w load, but I want a long runtime. In the future I may mod the UPS to attach some really large batteries, but for the time being I will use the stock ones

• Question 1 - The transfer time for the older SUA1500RM2U is listed as 2ms, and then for the newer SMT1500RM2U its listed as 4ms/8ms max. Why does the newer UPS, have a slower transfer time?

• Question 2 - The SMT1500RM2U and the SMT1000RM2U have the same physical dimensions, however the SMT1000RM2U has a smaller battery capacity. The images of the battery trays look the same though as far as I can tell (APCRBC132 and APCRBC133). Could I just upgrade the batteries in the SMT1000RM2U to have the same capacity of the SMT1500RM2U? I don't need anywhere near to 700w or 1000w of load capacity, so the size of the batteries is really all I care about. I will probably end up buying the UPS with no batteries anyway

[JonPro]

Hi @farkhispe,

Thank you for reaching out to the SE Community, my name is Jon and I will assist you with this query.

Our Smart-UPS that uses the line interactive topology has an advertised transfer time of 2-4ms and through the years and changes in the design and internal components would have an effect on this.  Also, if you would like to increase/decrease the transfer time of the UPS, you'll have to adjust the sensitivity of the unit.

Please see the reference below that explains the statement above:

What are the different sensitivity settings of a Smart-UPS?

We also recommend for you only use the approved battery capacity of the UPS as the charger is designed for this reason.  Using a much more higher capacity might lead to premature failure of the charger.