With only a 700 watt load on the charger it indicated a heavy load. Called factory service a they tried to tell me my tools must be to blame. When I told them I was using a Fluke certified instrument they then wanted to know the inrush current. I told them that there was little inrush current with the load being incandescent light bulbs. They would not admit there could be anything wrong with their product. Will be returning this charger ASAP. I do have to say this is the first Tripp Lite charger I have ever had a problem with and am disappointed with their service department .