how to add a starter only battery

[Jimongee]

Hello,
I have a 2002 356. It currently has 2 12v batteries. I want to add 3rd 12v battery for engine starting only. My question is how do I isolate that 3rd battery so that the engine alternator and the onboard charging system will still charge the original battery bank and the additional starter only battery?
thanks for any advice.
Jim
SV SamiDog

 

[Steve Dion]

Jim:

Are you sure that your boat is NOT already wired that way. I have never seen one that was not wired that way from the factory. Normally there is a 1-both-2 selector switch that allows you to run off of one or both batteries.

If this is the case you can move one of your batteries to the "house bank" (wired in parallel) and purchase another battery for the starting bank.

Check your charger, they may have some specs for this type of setup. I know that our Xantrex XC charger specified that the "House Bank" was bank 1.

 

[Stu Jackson]

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

http://www.westmarine.com/webapp/wc...01&page=Batteries-Second-Battery#.UatiJJymXFk

 

[Paul F]

The easiest way to connect starter and house batteries for charging is to use a "combiner". This small device automatically connects the batteries together when the voltage reaches 13.5 volts the batteries connect and charge all batteries. When the charging stops the batteries disconnect. The great thing about this device is that all you do is install it and forget it. Any marine/rv store likely has one.

 

[weinie]

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

http://www.westmarine.com/webapp/wc...01&page=Batteries-Second-Battery#.UatiJJymXFk

Stu... you really need to have the mods come up with a way automate this reply.
I mean, we already know you know your s*#t... no need to get to 100k post counts to prove it!