When connecting various components, it’s important to get the wire sizing correct. There’s various opinions about the correct size wire for each application, but the general theory is that the wire size needs to get thicker for the longer the run and the more amps you’re drawing. If you’re pulling a huge load over a long distance, it’s going to be some giant cables.
Remember that when determining your run length, you have to include the positive and negative cables. For example, if your inverter is three feet away from your batteries, then you’ll need to look at the “6 foot” lengths on the charts below.
I’ve included multiple charts because there’s multiple opinions on what size wire gauge is best. In the BlueSea chart, they even include the concepts of a 3% voltage drop or a 10% voltage drop. Depending on your situation, one or the other might be acceptable to you.
You can click on any of the charts below to get the full-resolution version.