Ground for dual battery setup

[4runnerAzGuy]

I'm hooking up my dual battery setup. I was wondering, has anyone used the hooks on the engine as a ground? I would think they would be a great ground since they bolted to the engine and they would be a solid point. What do u guys think? Or is there a better ground that I could use to ground my accessory battery?

This is the hook I'm talking about

 

[ebg18t]

I ran mine down to the Engine block mount to the frame.

 

[riceandpho]

i would upgrade both grounds, clean the metal up and use that, also sand the body and do that one also, do this with the second and also the primary battery.

 

[macgyver_ga]

i would upgrade both grounds, clean the metal up and use that, also sand the body and do that one also, do this with the second and also the primary battery.

This ^^ 100%