i modified my UPS so itll last longer. i moved it from its existing case into a small computer case and added some fans (since it gerts hot enough runnin from just 1 battery).
the only changes to the UPS was a 70A relay to switch on the external battery when the power had failed, and to switch the fans on. it all works etc but the problem is, every 7-8 seconds it makes a noise for a second. it sounds like a large transformer under load. it gets fairly loud (compared to normal) then gets quite again. is this normal or should i be worried?
the only changes to the UPS was a 70A relay to switch on the external battery when the power had failed, and to switch the fans on. it all works etc but the problem is, every 7-8 seconds it makes a noise for a second. it sounds like a large transformer under load. it gets fairly loud (compared to normal) then gets quite again. is this normal or should i be worried?