Would this work?

[AR.223]

 

[earl60446]

Should work, probably be best to have a matching set of batteries. Although the trolling motor battery will be discharging more rapidly with heavy use.

On second thought, the relay may fry if one battery is undercharged compared to the other one. GUEST battery switch may be best idea or very heavy relay.

Tim

 

[dieselfixer]

X2 on what Earl said You could use a Ford starter relay they used to mount them on the fender under the hood they are small and will carry a lot of load

 

[Steve A W]

The Ford solenoid won't hold up to the continuous activation.
We learned this with an old firetruck.
But there is a relay/solenoid that is made for continuous duty.
If You have a good auto parts store, they should be able to set You up.

Steve A W

 

[earl60446]

Another thing about the GUEST switch is you could charge one or the other or both. Gives you the option of choosing which would be desirable in this situation. Also provide the option of using either one for starting outboard.
Tim

 

[dieselfixer]

Steve You are correct about the Ford relay the fine wire in the pull in coil would burn out quickly. Thanks for the info.