That would have got by me as I did not know that LED lights needed more voltage than regular lights in fact since they're more efficient I'd have thought the opposite that they work on less. That is REAL LOW voltage tho. I'd double check the meter readings by running the ground lead all the way up to the batt neg post. I'd clean EVERY connection & I'd see what I have for charging voltage at a fast idle at the batt & at the alt & see what you have at the bulkhead/fuse box etc & go from there rearward. Any terminal/connection is a potential voltage drop from high resistance