Wiring extra battery

[elittke]

I have an older 1983 Catalina 38, with the basic 2 battery system. Both deep cycle/starting. I want to add refrigeration and therefore a dedicated starting battery. Or a dedicated refrigeration battery so I can still have power to start the engine. Any input on how to wire this would be appreciated?

[Sandero]

Put your biggest batts in parallel and have the 3rd as the start batt. Have the alternator charge the main pair (house bank) and use and Echo charge to charge the start batt.
Get a switch that can turn you batts on or off or even combine them if necessary (dead) start batt. Look at BlueSeas

[Joel E Felt]

Thanks this helped me out also. To everyone at sea, Merry Christmas - joel

[brianlara 3]

Thanks Joel.

[Sandero]

Here's my 12 wiring...

[Stu Jackson]

Like this:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

[elittke]

Ok, thanks! It will take a bit of time for this to all sink in. So I am wondering if I add a small refrigerator, will I need a third battery or will I get by with the 2 big ones that the boat has?

[exMaggieDrum]

No one can tell you if the batteries you have will be adequate for your uses as the number of factors to consider is long, as is how you will use the batteries from day to day, month to month. Type of batteries, draw from all your devices (including refrigeration), location you will be cruising (hot, cool, etc), age of the batteries, how they have been maintained, etc. etc.

You should not, however, have a separate battery for the refrigeration as another posted has already said. The refrigeration may be the biggest draw of all your systems, but it all depends.

[vtomanov]

Consider LiFePo4 battery for hiuse and start - 20ah for starting will do a great job for any engine start cca -1000+ and can be charged with wet cel, charger - I've done it myself and very happy so far ! price in the end about 3x cheaper then wet cells as LiFePo4 last 2000+ cycles as a minimum