Why are Eaton 5SC UPS runtimes so low?

[jrmymllr]

I'm looking at an Eaton 5SC750 UPS and the runtimes seem pretty low compared with APC. The Eaton has two 12V 7Ah batteries according to Eaton. Since the 5SC is sinewave output, I'm comparing it with a sinewave out APC BR1500MS2 which also has two batteries, although those seem to be 9Ah.

This datasheet claims 105W load on the Eaton lasts 36 minutes:https://www.eaton.com/content/dam/eaton/products/backup-power-ups-surge-it-power-distribution/backup-power-ups/eaton-5sc-ups/eaton-5sc-ups-technical-specifications-tn153004en.pdf

If I enter 105W into the APC product page it claims 70 minutes! https://www.apc.com/us/en/product/BR1500MS2/apc-backups-pro-1500va-900w-tower-120v-10x-nema-515r-outlets-avr-usb-type-a-+-c-ports-lcd-user-replaceable-battery/

That is very close to 2X the runtime, with not even a 30% advantage in battery capacity. What is going on here? Is APC lying? I do have a dual-battery APC unit but it's not sinewave, and the display claims 80 minutes with a load in the low 80s of watts. I haven't tested it that far, but it seems comparable with the BR100MS2.

I called Eaton and the guy didn't have a good answer but I admit this is only something the engineers there could answer.

On a side note, 24V at 9Ah is 216W-hours and makes either UPS appear to have a very low conversion efficiency.

[coppercone2]

ehh its a choice of how much you wanna discharge the batteries probobly. APC might deep discharge, which is why for a APC unit you need to include a crow bar and safety goggles in the battery replacement kit. Those cells swell up and get fat.


Other manufacturer might treat them better where you don't end up with bloating being standard procedure.

The converter are probobly highly efficient. The problem is the lead acid battery.

I think that probobly Eaton stuff lasts to spec and is servicable whereas APC turns your battery fat and has very low life time.

Eaton is a quality brand that ends up in high reliability stuff because they make electrical safety equipment so they likely can't have their name assosiated with bloating batteries that might die before the actual deadline. Meanwhile APC... well its APC we know about APC lol they probobly treat a battery like vin diesel treats a engine before a cuban street race.
APC : you can plow a field with a ford pinto
eaton : you can drive on the street with a ford pinto


the takeaway is
you can overload lead acid batteries quite a bit if you don't mind the consequences. Batteries in general have a wide performance range and ALOT of tradeoffs to be made with the end goal, and of all the batteries you commonly see, the lead cells have the most 'use options'.

[jrmymllr]

ehh its a choice of how much you wanna discharge the batteries probobly. APC might deep discharge, which is why for a APC unit you need to include a crow bar and safety goggles in the battery replacement kit.

I had the same thought in passing but I think you're right. Perhaps that's part of Eaton's "ABM" that's supposed to increase battery life, but the charging method is definitely most of it.