16-05-2023, 11:15 AM
(This post was last modified: 16-05-2023, 11:23 AM by Tony Griffiths.)
LEDs draw so little current that good earth is (as others comment) absolutely essential. I'd run separate wires from each headlamp back to the battery's negative terminal. Decades ago, to brighten the ordinary bulbs, I used to solder the wires onto the bulbs and run an earth return back to the battery. The difference in light output was immediately clear and a photographic light meter (remember those?) showed a reading about 20% higher.