OK I have a 24v 82 lb MG connected to two batteries, plus several other attachments to these two batteries, not sure what they are but I assume it's livewell, bilge, etc? Then I have a cranking battery (200 hp yamaha) and I'm pretty sure that my electronics (2x 1199 birds) are hooked up to the cranking battery. If I run one graph, I get about 11 volts on my graph, if I run 2 graphs, I get 9.5 or less, and sometimes the front one will turn off. If I only have the console graph on, and I start my motor, the graph usually turns off when I start the motor. So it seems that I should either run my electronics off my trolling motor batteries, or perhaps the cranking battery doesn't have enough power? It's surprising that it doesn't have enough volts to run the console graph and start the motor, but it is an 1199 not a tiny 5" graph. Or maybe I need a more powerful cranking battery?
Any input is appreciated. I don't really want to go with 4 batteries as top speed is already a bit poor on my boat.

Also I don't fish a ton of tournaments that are in big water or windy conditions, so running down my trolling motor batteries by running the graphs might not be that big of a deal.. I mostly do 3-4 hour evening tournaments

You didn't say what boat you have, or if it was owned by someone before you who may have butchered the wiring. I have never seen a bass boat rigged with other loads on the TM batteries unless someone has been butchering the wiring. That is not a recommended thing to do. Do you have an onboard charger? Could those other wires be the charging leads from that charger? That would make the most sense.

Accessories such as livewell, bilge pump, etc. are not independently wired to a battery. A boat's wiring harness feeds power to them from switches. Those switches get their power from a single cable attached to the battery. For this reason, I'm guessing you may not have awareness of how your boat is actually wired. Maybe a couple of pics could help.

You didn't say what size your starting battery is. (Group 24, 27, 29, 31?). I'm betting everything is running off this battery except for the TM. That's actually normal and OK - as long as you have enough battery and it is in good condition. You have a lot of load, so you need a lot of battery. If you have a short battery (about 10 inches long) that's Group 24, and way below what you need. I'm going to guess it's going bad too. You can check the cells with a hydrometer, or take it out and let an auto parts store check it. I bet it will be bad, or at least on its last leg.

With your statement about fishing only short tournaments, you can probably make do with a good Group 27 batter, but 29 would be better. You shouldn't need 4 batteries.

ah, yep - It's a 24 series cranking battery that's about 2 years old. the wiring is a bit of a mess, I got it used and the boat is a 97 skeeter zx202.
And you're correct that I have no idea how my boat is wired! I'll try a bigger battery to see if that works, and if not, I'll take a bunch of pictures and post them in hopes of getting it figured out. I'll also trace the wires to my on board charger so that it's easier to track down the other wires. I also have a radio hooked up but it's attached to the TM batteries

and thank you very much for the info!

Most who may be experts do not recommend running anything on the TM batteries other than the TM. With a full electronics load along with all the other goodies, you need at least a Group 27 battery, and 29 would be a nice bonus. Many tournament rigged boats moved up to a Group 31, as I did.

ok, I'm on a automotive store website, the optima blue top marine deep cycle group 31 is $292, but the optima blue top marine starting battery group 34 is only $220. is 34 too much weight / size? I don't see any 29 or 31 starting batteries, only deep cycle

I have never read anything based on other than personal opinion that says to run nothing but the TM off the TM battery. The exception would be if you are getting interference on your sonar from the TM. Even multiple sonars are not going to be that much of a load on the TM battery.
I run everything off the 12V battery in the 24V setup with no issues. If I start to see interference, I'll change it over.

My opinion, and we know what that's like, is to have nothing on your starting battery except the motor. You can limp home without lights and the stereo if you have to, but if you can't start the motor, it gets a little tougher.

The Group 34 is smaller, no wantie that one. Look more closely at that model D31M "deep cycle" blue top. It is actually a dual purpose battery with a 75 AH rating from a deep cycle perspective and over 1000 cranking amps from a starting perspective. It's a common choice solution for a lot of big bass boats with a 250 on the back. If you have a Sam's club membership, they have a similar honker of a group 31 AGM battery made by Johnson Controls for $200.

If you want to save even more, Sams has a conventional Group 29 dual purpose battery for $95.

glad I asked, I assumed 34 was bigger than 31!

also look at the Specs! Those give physical size and electrical capacity. The optima website is a better place to look at optima as they will have all the info. I currently use Optima D31M as my main battery, but when it eventually dies, I will probably save $100 at Sams and give that one a try.

I just replaced my Everstart/Wal Mart cranking battery that I put in use in April 2011. Never had a boat battery cranking or TM last that long. Battery is a group 29 with 850 cranking amps. About $100. Probably the same one as the Sams battery.

I just bought two Energizer Marine Batteries group 27 from Sam's. Cheap price at $80 each. Giving it a try and see how it work out. My battery compartment won't take any sizer bigger than 27. Tight fit. Would like group 29 batteries but I don't think it will fit. Current batteries are interstate battery. Lasted barely 3 yrs and dead now.

3 years is about normal.