[doaclnr]

Ok, I looked around but didn't get my question answered. I have 2 batteries now and Im thinking of adding a 3rd. 1 starting and 2 deep cycle for stereos and what nots. Any thoughts on this set up? My current system is getting drained after a few hours. Im replacing the batteries this week but was thinking of adding a third to avoid dead boat syndrome. I also just put on a 120 amp alternator a couple weeks back.

[z275st]

Mine came with a factory 3-battery setup. 2-starting and 1-house battery.

The Mariah Owners Club - Gallery - Cockpit Photos

The two on the right are starting on left is the house/deep cell. The starting can be switched 1-2-All(1+2), house is isolated and has its own switch under a rear seat. I guess they wanted the safety of two starters over two house batteries. Better a dead radio than dead engine. Also a main cable goes from the alternator to a three way splitter then to each battery. I'm thinking to keep each battery from draining the others.

[doaclnr]

Interesting... I did some recon after I took the batteries out. They were both regular cell batteries. The perko switch has one line coming in from the alternator but after reading your thread maybe a splitter for each battery? Any reason I cant split off the one alternator line? Im thinking a deep cell for radio and regular for start. Just sticking with 2 batteries... AAAANNNNDDDDD Ill keep a jump box in the boat from here on out...

[z275st]

My house battery is a deep cell/starting and i keep jump cable to use if I need to jump to the starters.
If you have one cable from the alternator you will drain power from the starting battery and the house battery while sitting and using power for radio, be sure there is no connection between both battery (+) post for isolation of house/deep cell power.

https://www.youtube.com/watch?v=wR_WWqL1ufM

Amazon.com: 90 Amp Dual Multi 2 Two Battery Isolator- Marine, Rv, Ems: Automotive

CHARLES MARINE Marine Multi-Battery Isolators | West Marine

[Brewfixer]

Here is a drawing of what I did in my Z222. Originally came with 2 batteries.

[doaclnr]

Ok, Ive decided to go with 3. The new deep cycle I bought was bigger than the standard battery so I have to buy a new battery box and cables. Ill do a 2 start and 1 house (deep cycle). Do I have to have and Isolator or can I run the 2 starters batteries together and the house on its own? Like the diagram above minus the isolator and charger.

[Brewfixer]

Originally Posted by doaclnr

Ok, Ive decided to go with 3. The new deep cycle I bought was bigger than the standard battery so I have to buy a new battery box and cables. Ill do a 2 start and 1 house (deep cycle). Do I have to have and Isolator or can I run the 2 starters batteries together and the house on its own? Like the diagram above minus the isolator and charger.

You have to keep in mind that you need to charge them. Once you land the charging system on 3 batteries they become as one. The isolator prevents the house batteries from draining the starting battery.

[doaclnr]

Correct... Im going to install the isolator and set it up like yours but Im going to have 2 starting and 1 house. Like z275st said, better a dead radio than boat! 1 deep cycle should run several hours of radio and phone... I also saw a post of somebody taking out the inline fuses and putting in a fuse panel. My 00 272 had that set up. Im going to do that too. You have pics of how you mounted all your items?

[Brewfixer]

Originally Posted by doaclnr

Correct... Im going to install the isolator and set it up like yours but Im going to have 2 starting and 1 house. Like z275st said, better a dead radio than boat! 1 deep cycle should run several hours of radio and phone... I also saw a post of somebody taking out the inline fuses and putting in a fuse panel. My 00 272 had that set up. Im going to do that too. You have pics of how you mounted all your items?

If you look at the drawing the fuse panel is one that I installed under the console on the starboard side bulkhead. That is where my stereo, GPS, LED and power accessories are landed.

Leave the bilge pump and power hatch (if equipped) on the starting battery. IMO... The 2 starting battery idea is an overkill and waste of a good battery. If done like the drawing, you should never have any issue with the starting battery. What I did is when I purchased the new battery, it became my starting battery and the 2 old ones became my house batteries. Additionally, with the setup as I have it you can link all 3 batteries together in a pinch which after 4 years I have never had to do. I can play my stereo and have my LED lights on for at least 4-5 hours and never had an issue.

[z275st]

doaclnr,
As you can see you may find many opinions on a subject. It has much to do with your unique boating habits on what is best for you. Personally I felt that when a multi-million dollar boat manufacture company with a research and development department designed a boat with two starting batteries I wasn't going to change it. On a couple occasions I have been on the lake and needed to use both 1+2 batteries to get my engine to turn over, but I go out for 3-4 day trips and away from an outlet to plug in my on-board charger.I make many short runs and may start my engine 50-100 times in a day pulling skiers and tubes. If you only do day trips and have a run time to recharge the starting battery then one is probably fine. if you have a large engine it will take more amps to turn it over again and again. Do what makes YOU feel safe. There really is no RIGHT way.
I would use an isolator with any combination unless you use switches to separate the batteries, remember any direct line large or small from one (+) post to another will drain power from both batteries. You could isolate both starters together if you want, but each time you start it will draw power from both.