Need Help/Advlce about battery setup on twin crusier

[Duke_]

Ok, ill try and keep this short and simple, its a rather complicated setup i have no experience with, i have a few ideas on how to better it but i would like to hear from people what the proper way to go about setting this up.

I have a Silverton with twin 220's, right now there is 2 batteries, PORT motor has ON/OFF switch for battery and is charging the PORT battery, STARBOARD motor has ON/OFF switch for battery and is charging the STARBOARD battery, the boats house accessories are split between both batteries and wired into the ON OFF switches (Fridge, and water pump on PORT battery, and lights,radio, etc on STARBOARD battery). Now where i get lost is both batteries are wired + to + and - to -(in parralel i believe its called), so i think theres really no isolation between batteries. what i found last year.. this would leave me stranded after a day on the lake(not good). I want to fix this up right before i drop the ship in the water this year, what are my options and how should i go about fixing this, i had thought about a switch to a 3 battery setup and have 1 starting battery for both motors and run a bank of 2 house batteries for everything else.. im just not sure how to get there from where i am now. If anyone has some advice or can explain why the previous owner set this up in this fashion?. Can i get away with a single battery to start twin engines reliably?

Thanks

 

[Don S]

Re: Need Help/Advlce about battery setup on twin crusier

Twins can be a challange to get wired so they are easy to understand and use.

I would suggest you have a starting battery for each engine, a two battery bank for house, and two Bluesea add-a-battery ACR setups.
Basically a battery switch for each engine, both charging the house batteries while keeping the individual starting batteries isolated from the house and from the other engine.

 

[Duke_]

Re: Need Help/Advlce about battery setup on twin crusier

ok so if i go that route i have 4 batteries (3 banks, port starting, starboard starting, and 2 house batteries in parallel) its ok to have each motor charging the house battery bank at the same time via the "add a battery" even tho they are connected together? or should i only have 1 Add a battery and let the starboard battery handle charging the house battery bank on its own, what im thinking now is instead of 4 batteries i will go with 2 starting batteries and 1 larger house battery and connect all the house accessories to one battery and leave the starting batteries for the motor, can you still use 2 add a batteries and have them both hooked to 1 house battery?

 

[Don S]

Re: Need Help/Advlce about battery setup on twin crusier

No, it won't hurt to have two charging sources going to the house batteries. When the batteries are fully charged, the regulators in the alternators basically shut off the charging until needed again.

The ACR doesn't care if the house battery bank is 1 battery or 10.

 

[Duke_]

Re: Need Help/Advlce about battery setup on twin crusier

No, it won't hurt to have two charging sources going to the house batteries. When the batteries are fully charged, the regulators in the alternators basically shut off the charging until needed again.

The ACR doesn't care if the house battery bank is 1 battery or 10.

Thanks, i went down to the local marina store and spoke with the mechanic there and he thought i was getting into much too compicated of a setup, he suggested i stick with dual batteries and later i can add an additional battery to one bank with an isolator and use that bank for "house" when out on the lake anchored. So with his suggestion to keep it simple i picked up a new 1-2-BOTH switch and plan to replace the two single switches, so in essence i would run both engines through 1 switch. head out with the switch on BOTH, and use bank 2 while anchored for house and use bank 1 to start the motors back up and then switch it back to BOTH for the trip home, let the shore charger top everything up when were back.. is this safe for my charging system with twins?

 

[trendsetter240]

Re: Need Help/Advlce about battery setup on twin crusier

With the single 1-2-all switch, two batteries and two motors the wiring goes like this:

Starting battery pos to position #1 on the switch.
House battery pos to position #2 on the switch.
Starting battery negative to house battery negative.

All electrical positive feed (fridge, pumps, radio,) everything to the common terminal on the switch. (Best to use a positive bus)
All electrical negative feed to the negative terminal on the batteries. (Best to use a negative bus)

Both engines positive connections to the common terminal on the switch.
Both engine negative to the negative on the batteries.

Switch to #1 to start, Both (all) while cruising, #2 while anchored and off at the dock.

Wire the float switch for your bilge pump directly to the house battery positive terminal.

 

[Duke_]

Re: Need Help/Advlce about battery setup on twin crusier

ok thank you very much, should there still be an isolator or relay so while operating in BOTH position the drained battery gets the charge?

 

[trendsetter240]

Re: Need Help/Advlce about battery setup on twin crusier

That is an option yes but not required. Without an isolator both batteries will be charged to the same level.

 

[Duke_]

Re: Need Help/Advlce about battery setup on twin crusier

OK thank you both for taking the time to give me a hand!! much appreciated.

 

[Don S]

Re: Need Help/Advlce about battery setup on twin crusier

While the system I described does take a bit more to install originally, it's a lot easier to deal with than the 1,2, Both switch.

When you get to the boat, you turn both switches to on. There, you are done until your trip is finished and you shut the switches off.
You can run the house batteries dead if you want and never touch the starting batteries. It automatically charges the house batteries when you do start the engines.

No turning the switch to 1 to start, then both to run, then 2 while anchored, 1 to start, both to run. Geeez, you spend way too much time trying to remember to change the switch and changing it for me.

 

[Don S]

Re: Need Help/Advlce about battery setup on twin crusier

You can still use an ACR and a single starting battery along with a single house battery and still not have to do a lot of battery switch changing every time you want to do something.
just wire it like this.