Why won't my no 1 battery start my motor?

[fish brain]

All grounds should be interconnected.

Mine are connected exactly like this. should both batteries be wired to the bus bar?

 

[ReelSlim]

If it’s wired like this then both batteries are basically the same point as the bus bar which is what you want.

 

[gunnerlove]

I would ditch the 1,2 switch in favor of the acr system. In my opinion it’s a far better setup. You can then run one house(deep cycle) and one start battery and the system will regulate the charge itself. The switch is just on/off. Starting on a deep cycle will wear it out prematurely as will deeply discharging a starting battery running electronics and riggers all day not how they were designed to be used.

just my opinion maybe worthwhile when it’s time for new batteries?

Mixing starting and deep cycles is a good way to boil the deep cycle into an early grave.