Battery 101 Question

[David Pendleton]

I'm hoping some of you RV guys can answer this for me, since my boat buddies don't know.



I have two batteries connected to a Perko 1-2-ALL switch. When the switch is in the ALL position, the batteries are now in parallel; voltage remains at 12V, but are MCA and Ah are summed (or doubled if both batteries are matched)?



Thanks all.

 

[AEdelheit]

Correct, in Series you would double the voltage to 24 but in parallel it will be the same voltage but the amperage of both batteries

 

[David Pendleton]

Thanks. What about MCA/CCA?

 

[AEdelheit]

Well CCA is the maximum amperage output at 0deg, MCA is max amperage output at 32deg. So if you have 2 1000MCA 800CCA batteries is paralleled you now have 2000MCA and 1600CCA

There will always be some resistance in connections and wire but not enough to make a difference if everything is in good shape.

 

[David Pendleton]

Thank you!

 

[AABEN]

It is jest like your truck. When replacing's batteries replace both of them at the same time. GOOD LUCK

 

[RVTRKN]

Also for boats I recommend gel cell type battery. I have used diehards and other top brands and not last, but when I changed to a gel cell, I get twice the life.

 

[jelag]

My only comment is that these batteries in parallel will charge but only will come up to the charge of the weaker battery... that's why its suggested that if you need to replace 1 you replace both..... just like your truck batteries...