I get how to put the batteries in parallel. I'm more curious how you hook all the accessories up?. Do you hook everything up to one battery as normal? Or do you hook up to positive on one battery and neg on other? How do you hook motor and charger up?

Just hook up to one battery as normal.

Does your charger charge the second battery when hooked up normal to one battery?

Yes

This is how I run mine... Its redundant and pointlessly excessive on my rig, but it came that was and I don't see any reason to ditch battery #2... Though I suppose when I had to replace them I could've gone down to one and saved money and also weight but there is also an extra battery in my TM battery compartment... So 5 total...

Spare battery life is never a bad thing though I suppose, and she has 2 bank chargers on each side to juice them up all the same... Then again I'd probably pick up 3mph if I dropped 2 batteries worth of dead weight right off the transom I bet!

It alsp shouldnt matter where you hook up, power side is power side and ground is ground, if you have enough extra comnectors at battery to justify it... But at that point you should be seeking a more elegant control circuit setup than running everything directly to batteries I reckon.

I had a couple people on here tell me not to do this...that it would mess things up.

I went ahead and put an extra battery in the boat next to my cranking battery. I wired it to my cranking battery must like you would if you were putting jumper cables on it (pos to pos/neg to neg (parallel)). It's been like this for about 6 months now and I've had zero problems. I do not have a battery charger hooked to the additional battery. It simply charges through from my starting battery when it's plugged into the charger.

As far as how I everything run....I have everything in the boat except the TM running off the one cranking battery which is backed up by the battery I added.

And, running batteries in parallel, you get more bang for your buck, so to speak.

For anyone wanting to get a bit more into the science/math behind batteries, this man's series is worth watching.

This one in particular about the extra oomph of two batteries in parallel:


Batteries in Parallel configuration

Brad

Two batteries connected together in parallel (pos to pos and neg to neg) will give you 12 volts but you have the juice of two batteries instead of just 1 so that will give you a longer run time on 12 volts. Just come off one battery to go to the + and - of your accessories if that is easiest to do. Since they are connected in parallel it doesn't matter which + or - post you come off of.

I was always told that you had to hook up to one post of each battery to get the benefits of that setup. So positive of one battery and negative of the other on all things that are hooked up.

hum might do this.

Whatever is the easiest way for you to hook them up is the way to go. It makes no difference if you come off both posts of one battery or one post of each battery. Google "connecting two batteries in parallel" and you will see pics. of it done both ways.

You have to when the batteries are connected in series.

Check out every diesel pickup truck on the market. Everyone of mine has come with dual battery hooked up in Parallel. They are going for the extra "oomph" mentioned above to rapidly turn over a very high compression motor. The second battery is simply hooked positive-to-positive and negative-to-negative. The starter, all accessories and the alternator are hooked to one single battery. Though they are identical batteries I call this the "main battery". The secondary battery is simply like a "jumper" battery off to the side. Even with everything run off one and only a positive and negative jumped over to the main battery from the "secondary" battery they both lasted 7 years on my current Dodge Cummins. This is the set up I would reccommend for your application although I think it's overkill to haul around the extra 50lbs in your bilge area. I would also question wether or not your batteries will be maintained in at a proper charge when stored unless you have them hooked to different banks on a multi-bank automatic battery charger(even more added weight). 361v

Just out of curiosity as to why you are running 2 starting batteries? Do you have that many accessories that you are afraid of not having enough juice to start after fishing all day?
I've been kind of worried about all the new electronics I've put on the boat and if it would drain the crank battery too fast. Mine is a crank/deep cycle so hopefully not but I don't ever want to find out.

Big agm group 34 or 31,would provide enough juice for everything you need on a bass boat. Running 2 in parallel is overkill, imo. I can see the potential benefits, but the you are adding 60-70 extra pounds back there. Every 50 pounds equates 2-3mph loss on top end. Not important to some, but just an FYI for you .