Adding a third battery ...diagram?

[mytime]

Does anyone have a diagram on how to add a third battery to an existing two battery bank? I have an idea on how to do it but would like a second opinion.

My existing set up is (standard set up) one alternator, battery switch (1-both-2), 2 output battery charger. I did not see a battery combiner anywhere.

If I need to upgrade to a 3 output charger that is fine but would prefer to use my existing charger.

My use for third battery is to dedicate it to a amp and sub-woofer also adding an electric head drawing 20 amps per flush.
However I want the option to switch into existing battery bank if needed for starting in an emergency. Thanks for any input.

 

[woodster]

you only need to post this query in one main thread it will get answered

 

[mytime]

Thanks..tried to delete redundant post...but apparently I can't figure it out.

 

[woodster]

Thanks..tried to delete redundant post...but apparently I can't figure it out.

don't worry about it ....no harm done ...i have seen this many times befor and the problem is not that you double posted as much as when you check for replies you have two to check instead of only one ...this format is new to all of use so we will have to learn together...but so far some of the things i have figured out was when i was eating ice cream cones ..and being the kind of guy that slaps his forehead when the lights comes on has messed up a lot of ice cream

 

[Jack - La Paz Mx]

I just added another 1,2,both switch so I can switch any of 4 batteries in line, all together, or 2, etc. Batteries should be same age and other similar characteristics. I can connect battery 1 to battery 3, 2, to 4, or have them all in parallel for charging. Put one extra battery under quarterberth, other on port side under cockpit. Use very heavy gauge wire (good welding wire works). My batteries are group 27.