Battery charger question, which leads go where?

[MGrande305]

Battery charger question. Just got my 243vrx out of storage today and installed a noco genius 2 bank battery charger. I noticed one of my batteries has 2 yellow negative wires and the other battery only has one yellow negative wire...anyone know the reason for this?

 

[Dean P]

I figure it's grounding something somewhere on the boat. I do not know why. I did check mine and I have the same thing. The 3rd yellow wire is for my amp (the one in the back).