UPS for my needs (long run-time)

[drummerdimitri]

I have two pc's at home that I game on.

They consume about 400W while gaming and I need a UPS that will be able to keep them online for as long as my external batteries will last (2x38AH 12V in series).

I have found the 2500VA model of this http://www.pceups.com/products/inverters/xpl available at my local computer shop.

Since it is rated for 1500W, does that mean it can run a 100% duty cycle assuming I can run it from a 1500W DC power supply?

I will only realistically use 1/3 of its capacity now but maybe benefit from the extra power in the future.

Reason why I'm asking is because I've been modifying UPS's with internal batteries to accept my large 38AH batteries expecting much longer runtimes but they seem to shutdown way before the batteries voltage drops low enough or because they overheat.

The batteries should in theory last around 1:30 hours at a 400W load but what UPS will I need for this to work? should I just buy the one mentioned earlier even though the runtimes are not stated in the data sheet?

[Kevman]

I have a hard time imagining a 2500VA UPS overheating under a 400W load.

You could also get a double-conversion UPS  such as this one:

 https://www.tripplite.com/smartonline-120v-750va-600w-double-conversion-ups-2u-rack-tower-extended-run-snmpwebcard-option-usb-db9-serial~SU750RTXL2U

They work by always running off of battery, so it'll definitely be able run indefinitely at full power even of battery.

Supposedly has a loud fan, though.

[Bratster]

A lot of UPS's also have either hard-coded or sometimes changeable parameters expecting how big a battery bank is. So they will think the pack is empty even when it is not if it's larger than expected.

You might look into an APC smart UPS. The older ones still work great and are very well-documented on the communication protocol and what values can be modified. I have a 2200xl, you can tell it how many external batteries are connected. It will then adjust the run time calculation. You can also go in over serial and adjust values not normally seen by the user, to change the charging voltage Etc

Sent from my Nexus 6 using Tapatalk

[james_s]

It could be overheating, many UPS's use simple heatsinks that essentially rely on thermal mass, which works ok if you're only running it for a few minutes. If you want to run for an extended period you may have to add a fan and/or larger finned heatsinks. Even a small amount of heat produced will build up over time if it has nowhere to go.

[drummerdimitri]

I've found what I was looking for: https://www.cyberpower.com/ww/en/product/sku/CPS1000E

Bought it since it has two fans and it built like a tank!