Bought a high output soldering iron for all those cable connections using large cables and where absolute connection certainty is required. The finished quality of the tool is poor, mine came with missing screws and was actually damaged in transit
https://www.ebay.com.au/itm/500W-220...AAOSwJJRZqS3st
due to inadequate packing materials, however after a bit of stuffing around I got it working. It takes about 10 minutes to reach soldering temp, but once there, cable size such as on winch or dual battery connections are a breeze. Recommend it for the workshop - unsure what size inverter you would need if wanting to use it mobile.