What gauge wire from batteries to inverter

Cable size to a large extent depends on what the demand will be - i.e. whether a resistive or reactive load...Resistive loads (like a hair dryer) are dumb loads and not as problematic as are reactive loads (say a large microwave, or vacuum motor) which will have an initial surge rating of 4-5 times the listed appliance amperage...So for reactive loads (in addition to mere wattage) you must also consider the inverters surge rating, thus cost will vary as not all same wattage inverters will perform the same...Take short cuts and you’ll be a candidate for a project redux - evaluate appliance surge conditions...A low voltage alarm or shutdown at the inverter is often due to a bottleneck caused by undersized or too long of round-trip cable run...Consider too that your future appliance needs may increase the demand on the inverter... For these reasons, from the outset I’d recommend 4-0 welding cables - a slight premium yes, but less voltage drop to inverter (absence of annoying alarms) and cheaper than buying cables twice... Just my experienced opinion...

3 tons