[Chuck v]

Jeremy,


If you look in the article about four each 6 volt GC batteries you will see how the cable connections should be made. It is still true that you need to have ALL batteries in the bank from the same manufacturer and with the same date code. The reason is the following:


When you charge flooded lead acid cells in parallel the least charged cell has the highest internal impedance, so it will absorb the least current if there is an alternate parallel path. In the best case this increases the time to achieve a full charge, and many cases badly matched batteries may not come anywhere close to achieving a full rated charge.


Conversely, in a series stack, this higher impedance causes a disproportionately larger voltage drop across this cell, so it will charge more than its neighbors until the charge state and voltage drops are balanced out and this results in the best charge outcome relative to recharge time.



Therefore, if you have the option, use cells with a higher amp-hr rating and connect them only in series to achieve the system voltage you are desiring. This is why the off-grid home I had used L16 batteries just in series, and not GC batteries in series/parallel. Those L16 batteries had a service life of more than 10 years. Of course, I had plenty of height for these L16 batteries, you would not likely have space for any of these in a motor home. and they are a beast to maneuver around since they weigh almost 120 pounds each!!


Chuck