So I just got a used UPS (Uninterrupted Power Supply) I put in fresh batteries and the unit seems to work great. My problem though started the other night I noticed that every time my well pump kicks on the UPS switches over to Battery power for a split second and then switches back to AC power. Just wondering what you guys think could be causing this. From the manual for the UPS the Error code says low voltage is the reason it is turning on. How can I fix that?