Ford 555c Backhoe. Only clicks without boost. New battery. Wondering what the wired button is in battery box? Bad connection somewhere? Fires right up with mega boost and runs great but can't shut off away from power cord.
Bad connection or cables. I solved my starting problems with new cables.
Just replaced positive cable on Deere 50d… solved similar problem. Cable looked perfect at battery & starter ends, but middle portion was badly corroded where sitting on carbody (Problem started in the spring after a cold winter, moisture within insulation jacket down to low point?)
X3 for cables. I replaced mine on the 555e and have no issues now.
Why not measure the voltage drop and find where the problem actually is instead of guessing?