You can google my past posts with photos. Parallel-reversed diodes with a forward drop ~0.5 V (at ~100 A). I measured ~0.75 V drop in the ammeter circuit at ~50 A output. The diodes I used are rated ~200 A and need a heat sink (can be the copper wires). Don't try it unless you understand basic electricity and DC power. In my post, one reader who doesn't kept arguing with an engineer (me) about resistance, which he didn't understand. A diode has a curved voltage drop vs current curve, which can't be summarized as a linear resistance value.