I have a cranking/deep cycle battery and a deep cycle trolling battery (both everstart) in my boat.  What battery should I hook my electronics to? (2 sonar, aereator, bilge, lights, etc.)  Just want to get the most out of my batteries.

Assuming you have 1 battery for the engine & 1 for the trolling motor hook everything to the battery that starts the engine. If you hook everything to the trolling motor battery you could have a low voltage problem as you run the trolling motor.

You dont need to hook everything to the starting battery either....Most manufacturers do not recc that..you may need to install a second battery and depending on what motor you are running you can run an isolator lead from the motor to the aux battery....If you run everything off your cranking battery you take a chance of running it low and then what are ya going to do..the motor wont start and trolling motor running low..i guess you can always row your way in....

I have one for the engine and one for the trolling motor.  If i hook everything to the cranking battery, would the lights and 2 sonar units run the cranking battery down?  Would it help to connect the 2 batteries together?

I would run and isolator in the boat..this will let you use one alternator source to charge 2 batteries that way you wont have to worry baout your starting battery going dead.

most bass boats use 24 volt trolling motors and that means ALL of the 12 volt stuff is hooked to the cranking battery. They do this because it is going to get recharged throughout the day by the alt. scbassin is exactly right. This is only a guess but I would say it would take a week for a livewell(on a timer) and fishfinder to run a cranking battery dead.

Well, ok I work for a manufacturer and it is not reccommended, I informed him of the way we reccommend it being hooked up and yes your right they are normally hooked that way, but that does not mean it is right.

I wouldn't hook the batteries together.  Since they are different types to start with, it will probably be more grief in the long run.  The weaker one will cause added draw on the other and shorten the life, or that has been my experience.  I think I have everything hooked up to the cranking battery or it was.  I usually carry an extra so I may have changed it.

Ok I am done trying to explain this to yall...I suggest you do some research on MArine Battery Isolators...Cause obviously you dont know. an isolator does just that isolates each battery from each other...They will not take charge from one another..an isolator is like a switch...It senses which battery needs a charge then charges it and then switches to the next.

Thanks Eagle, didn't know about the isolator just ordered a 1-2-70 for my boat from your link. The cranking battery that came with my boat was a group 24 left me dead two times didn't last with livewells, lights and accessories running so I got two group 27 batteries and hooked them up parallel which maintains 12 volts but doubles the run time of the weakest battery didn't have any trouble so far didn't leave me" DIW "dead in the water solved that problem. Will install the isolator when it comes. Everthing but the trolling motor was hooked to the cranking battery from the boat manufacturer there was no recomendation to use a seperate battery from Tracker or the dealer for the accessories.

Thank You

The Pa Angler

I hook everything to my crankin battery, 2 graphs, 1 flasher and all the aerators, bilge etc. If your battery is in good shape  you shouldn't run it down. If you do you need to get it checked, your accessories don't draw that much amperage.