How do I increase UPS backup time?

[Maung Pru]

I have been using sendon 1000va ups with 2 x 12 volt 7aH batteries. I replaced two 12 volt (17 plate) 160 aH lead acid batteries for long backup for 1 Fan and 40 watt 2 energy saving light. Backup time only 7 minutes! And switch goes off, and need again switch on for another 7 minutes.

What should I need to do for increasing backup time?

 

[tpetar]

Check temp of MOSFETs heatsink inside UPS, they are small. That UPS is not designed to work for longer time. Replace heatsinks. I will not exclude even usage of some timer.

 

[rfredel]

Hello Maung Pru,

can it be, that your new battery is not fully charged. The charging current of UPS is not strong enough to charge the big battery in time.

Look for the battery voltage under load. It must be >11V else the battery is empty.

Regards

Rainer