Originally Posted by RockyMtns
I've just added two 6v batteries and created a sealed & vented compartment under my dinette. Now I'm trying to decide if I should leave my original 12v single battery on the tongue also or remove it. The advantage of leaving it would be to keep the additional amp hours. What would be the disadvantages (if any)?
If you opt for this, I would install a switch to change between the two banks of batteries. The first bank (older 12 volt) and the second bank (newer 6volts in series) are different enough in size and age that the 12volt would be overdischarged when in use and overcharged when charging and the converter or other charger could misread the power "needs" of the bigger 6volt bank and undercharge it (those are basically the disadvantages).
The disconnect would allow you to leave it on the tongue in case you needed it but isolated from the new battery bank. Blue Sea makes a disconnect that allows you to change between bank 1, 2, 1&2 or none.