The correct way of connecting multiple batteries in parallel is to ensure that the total path of the current in and out of each battery is equal. Connect using positive and negative posts.
Solar panels can be up to 300 feet from the battery with high voltage and thick cables. To find the best distance, consider voltage, cable size, system efficiency, and potential power loss.
Here's an in-depth DIY (do it yourself) write up on a “simple” dual battery and solar system for your overland rig on a budget. It includes layout, component selection, required sizing calculations, and recommended tools. I've researched and compared with alternate methods to.
Stackable energy storage system delivering modular lithium-ion battery modules with advanced BMS, inverter integration, and scalable capacity for microgrids, solar-plus-storage, peak shaving, load shifting, and UPS backup in residential, commercial, and industrial applications.
You can purchase solar batteries from various retailers, including online platforms like Amazon, Home Depot, and Lowe's, which offer extensive selections and user reviews. Local home improvement stores and specialty solar energy stores are also great options for personalized.