Dual battery switch hook up

centextom

Cadet
Joined
Oct 17, 2007
Messages
28
Ive got a 21 ft Larson runabout that I have 2 batteries in. I have the second battery there just in case Im dead in the water so to speak, and Ill just switch cables or jumpstart. I want to put a battery switch in the boat to turn one on while we are anchored and listening to music, and have both on while cruising to keep them charged, but the switches that I see have instuctions going to a control board or somthing.
All I want is a back and forth, or both on switch. I keep them both on a tender in my garage when the boat is not in use.
 
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ac0j

Petty Officer 3rd Class
Joined
Apr 26, 2011
Messages
98

sschefer

Rear Admiral
Joined
Nov 13, 2008
Messages
4,530
Re: Dual battery switch hook up

BlueSea makes the switch you want. You can get it here in parts or at West Marine if you have one nearby. Simple switch runs in 1, 2 , both or Off. Easy hookup too.

Here's the one you want -
Blue Sea 4 position Part # 9001E
 

Fireman431

Rear Admiral
Joined
Sep 17, 2007
Messages
4,292
Re: Dual battery switch hook up

Here is your hookup:
 

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AZSenza

Chief Petty Officer
Joined
Mar 11, 2008
Messages
521
Re: Dual battery switch hook up

We've had Dual Batteries on Both our boats including our current 97 226 Lxi Larson. Very simple to hook up. The diagram is pretty good, all your "Power" comes from the common connection, as you switch batteries, thats where the power comes from. When on both you have the power from both batteries for a start. We ALWAYS use #2 battery for lounging, keeps it easy when we need to start. "Hunni, switch the batteries" dont even have to say which one!
 

flimsyjim

Cadet
Joined
Feb 17, 2009
Messages
11
Re: Dual battery switch hook up

The best for your application may be dependent on how your wiring is currently configured-
If it is indiscernable as to what wire is what at the battery, I would suggest going the OFF,1,2,BOTH switch (BlueSea 9001E as suggested earlier).
Adv- easier to install, easier to understand
Disadv- must manually operate the switch, could damage charging system if switch is turned to OFF with engine running

If you can make out what wires are engine and what are accessories, I would suggest the OFF,ON,BOTH switch w/ relay (BlueSea 7650).
Adv- does not require manual switching, the 2 banks are isolated so you can use accessories while cranking the motor without have to change the switch
Disadv- an additional part (&wire) to install

I installed the 7650 in mine and it took a bit of time and wiring to get it installed, but I am very happy with the results. When the motor is running the relay senses the voltage and connects the 2 batteries in parallel so they both charge. When you shut the motor off the relay opens and the banks are isolated. You can run an LED off of the relay to indicate to the operator the state of the relay. The relay will not close when the motor is running if the banks differ too much in voltage (~3v I think). The operator can manually connect the batteries by using the COMBINE setting on the switch to charge both in this situation. This only happens if you have been pumping the stereo with the engine off for awhile.
 
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