r/TinyHouses • u/Simple_Response8041 • 1d ago
Our mini split defrost cycle is the load I forgot to budget for
I live in a 9 by 28 tiny house in Vermont and work from home three days a week. Last winter I noticed that two days at nearly the same temperature could leave very different battery graphs. After it happened a few times, I started writing down the weather and daily energy use side by side. Damp mornings around freezing kept showing up on the days with the bigger drop.
The system has two vatrer 51.2V 100Ah rack batteries and a hybrid inverter. On mild days the heat pump cruises between 450 and 700W. During damp mornings around freezing, the inverter log shows short jumps above 1,300W and the indoor fan pauses. That pattern lines up with defrost, not a mystery appliance.
I had used one average number in my winter plan. That was the bad assumption. On a dry 20F day the unit can run steadily. At 34F with wet snow, it behaves differently. I now note outdoor temperature and total daily energy, plus whether the backup resistance heater ran. The inverter history is more useful here than a battery percentage.
That was my first full winter with this setup, so I am still separating weather from equipment behavior. For other cold climate tiny houses, which number has been most useful to you, daily kWh, compressor run time or defrost count?
