RV Inverter Size Guide: Watts, Surge and Battery Demand
A larger inverter can run larger AC loads, but it also demands more current from the battery system. Inverter size should follow the appliances you actually need to power.
Continuous and surge watts are different
Resistive loads are relatively simple, while compressors and motors can draw a higher startup surge. Compare both the inverter’s continuous rating and short-duration surge capability with the appliance requirements.
Large AC watts mean very large DC amps
A 1,500-watt AC load can require well over 100 amps from a nominal 12-volt battery bank after losses. That current level makes cable size, fuse selection and connection quality critical.
Idle consumption matters off-grid
Inverters consume some power even when AC loads are light or absent. Search for the model’s idle draw and consider whether a smaller inverter or switchable sub-circuit would reduce overnight battery use.
Do not size from one future appliance
Buying an oversized inverter “just in case” can increase installation complexity without improving daily use. Build around a realistic appliance list and only add margin where a known future upgrade requires it.