August 1, 20251 yr I have a MasterVolt Combimaster inverter charger which i recently repaired (blown IGBTs / Gate drivers). I have it wired as a backup / UPS with a pair of lithium ion batteries, it operates as expected, however there is this weird and suspicious behavior as it gets very warm while sitting there connected to mains fully charged in standby mode. Is this expected behavior? Even when operational, and inverting mode with a small load (<500w) it seems way cooler. My understanding is that when mains grid is powered and the battery is full, the inverter should only be operating in charging mode and only occasionally trickle charging which should be negligible in terms of power consumption. at least not enough to make it significantly warm.I have a suspicion that i overlooked something during repair, anyone who has intimate knowledge of inverter operation have any insight? I understand that the High Voltage IGBTs operate as a full bridge rectifier when in charging mode, could they be generating more heat in that state? Or could it be an issue with the high voltage rail buck converter having efficiency issues? Or is this all normal operation (kindly note that the fans are off during the whole 'float' charging state so i imagine the heat would accumulate, but with the thermal mass of the unit, i find it suspicious that there would be that much load during standby charging). Or is this normal behavior and am i worrying for nothing? Anyone with any insights would be of great value, What are other inverter brands idle 'float charging' temps /consumption like?
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