When researching other things I happened to spot these battery bus bars They seem fairly well built and might be just the ticket for someone wanting to connect several batteries in parallel (although not inexpensive at $160 for the red and black pair). Not having used them I can not vouch for their quality but the specifications sound good. You can find them on Amazon here: https://www.amazon.com/dp/B0BYCXS7R...N0587NSO3&ref_=list_c_wl_lv_ov_lig_dp_it&th=1