APC Back-UPS 400 ES Runtime

[graemeeme]

Brand new 400VA ES charged for a week then tested supporting two ADSL modems (draw 12W in total).  Runtime achieved only 55 minutes.  APC website UPS Selector tool claims 125 minutes for this load.  Have I bought the wrong unit?  Would changing to 650VA or more increase runtime?

[JonPro]

Hi @graemeeme 

Thank you for reaching out to the SE Community, my name is Jon and I will assist you with this query.  May I please know the model number of the UPS?

[graemeeme]

ES 400.  BE400-UK.

[JonPro]

From the runtime graph that I was able to find here, it shows that the minimum load is 45W with a runtime of 1 hour and 26 minutes.  In my experience, this has something to do with the low load that is attached to the UPS.

Have you tried charging the UPS to 100% and letting it run on battery without anything connected?

[graemeeme]

Hi Jon

Ran the experiment you suggested.  100% charged runtime 51 minutes with zero load.  Is this a faulty unit?

Checked router load while I was at it.  I need 13W back up for as long as possible.  What product should I choose if the 400 ES is unsuitable?

Graeme

[JonPro]

Apologies for the late revert @graemeeme.  Is it possible for you to add more load on the UPS?  I am thinking that due to a very low load that the UPS is behaving that way.