After about an half hour charging with 400 Watt, my infrared thermometer shows at the ventilation of the charger only 31.6 degree Celsius. About 14 degree more than the cellar.
The small waste heat is an indicator for a high efficiency of the charger.
Standby without charging only 0.9 Watt
Critic: The trickle charge is with 19 Watt very high. In the morning 7:00 am had been 2.45 kWh on the wattmeter, 2 hours later 2.49 kWh. I think the batteries would have been full at 3:00 am at only 2.37 kWh on the counter.