dual battery set up

[BOATINGmatt]

I have one battery connected for my starting, gps-fishfinder/lights/ and bilge pump and all accesories except the radio and vhf ( which adding to the boat)(20 ft wellcraft cuddy) all of the wires are very neatly secured and mounted to the boat and i would like not to disturb them. What i would like to do is to add a second battery to power the radio and the vhf that i will take with me when i leave the boat and charge at home, and bring it back the next time i go on the boat. I will install quick connects to make this easy....if i had to use this" carry on battery " to start the boat ( if the other battery failed) how could i set it up so i could easily switch over to it without disconnecting the regular battery. ....would there be a way to easily bypass battery 1 and use battery 2...thanks

 

[BLU LUNCH]

Re: dual battery set up

Welcome to the forum you can use a dual battery switch, do you have a V-20 also? If you do, were you aware of this site for Wellcrafts?
http://www.wellcraftv20.com/

 

[Silvertip]

Re: dual battery set up

Here is a diagram of a dual battery switch setup. Although it shows an outboard, the concept is the same for an I/O or inboard. You do need a switch with a field disconnect rather than one for an outboard. The concept of the switch is that everything electrical is fed by the COM (common) terminal on the switch except for perhaps an automatic bilge pump which should be connected directly to the battery. So -- the switch in the OFF position obviously kills power to everything on the boat while you are away. BAT 1 allows starting, charging, and operation of all accessories from BAT 1. Same for BAT 2. In the BOTH position everything is operating from both batteries and both are being charged when the engine is running. The idea is to switch to BAT 1, start the engine and then switch to BOTH while you run to your destination. Switch to BAT 2 (normally a deep cycle battery) for operation of accessories while anchored. This prevents the starting battery (BAT 1) from being discharged. When you are ready to go, switch to BAT 1, start the engine and then switch to either BOTH or BAT 2. Why BAT 2? Because you discharged it significantly while anchored. This gets it charged up quickly. If you set the switch to BOTH it would take longer to top off both batteries. NEVER - NEVER switch to OFF with the engine running. Do it once and you will never do it again as it will cost you dearly for charging system repair.

 

[Knightgang]

Re: dual battery set up

I agree that a dual batter switch setuo is the way to go. I have 2 batts in my boat and a dual switch like that. If you install quick connects on the Deep Cycle, then you can still remove it to charge at home, but the advantage with this setup is you can (like said above) recharge either or both batteries while underway...

 

[BOATINGmatt]

Re: dual battery set up

Thank You For You Answers..my Only Remaining Concern Is That I Have A 90 Hp Outboart..will That Relly Have Enough Juice To Charge Two Batteries?? Thanks

 

[RickJ6956]

Re: dual battery set up

You don't need to charge both batteries at the same time. In fact it's not advisable unless both batteries have identical specs and are close to the same age. (Otherwise the weaker battery could cause the other one to overcharge.)

You also don't need to rewire the boat. Just add the switch. If you're adding a second batt, make it a Deep Cycle Marine/RV. Switch to it to power the stereo and other accessories when you're not running. Use the other for the starting battery. A good rule of thumb is to charge the starting batt on the way out and the aux batt on the way back.

 

[Silvertip]

Re: dual battery set up

Batteries do not have to be the same size, capacity, age, etc. The charging system monitors "system" voltage so it will not overcharge one battery and undercharge the other when the BOTH setting is selected. However to maximize charging, set the swtich on the most depleted battery when running. That will likely be the "house" battery. Full output of the engine alternator will then be applied to the selected battery. Keep in mind that even with a single battery, you do not fully recharge it on a short run back to the dock. If the battery was deeply discharged you would need to run wide open for a couple hours to fully charge it. You can start the engine a dozen times or more on the starting battery before it would actually require recharging (provided of course the engine doesn't need to be cranked for extended periods). If you have AC power at the dock, install a two bank on-board charger. Plug in at the dock and both batteries will always be ready to go.

 

[BOATINGmatt]

Re: dual battery set up

THANK YOU ALL FOR YOUR HELP I THINK I HAVE IT NAILED DOWN..as per the excellent diagram posted for us by "Silvertip" where does the the actual positive and negative enter the loop to be connected to the fuse pannel and bus bar. i understand the concept that everything in the boat can be powered by each battery but whre do these accesiories/starter get hooked up?? do the poewr leads come from the switch. Does anythingother than the bildge pump (with float) get hard wired to the battery ....thank you