Join Date: Aug 2006
Location: Arlington, VA
Thanked 14 Times in 12 Posts
Rep Power: 12
Your questions have been asked and answered. To recap:
1. You need approx 40-60A battery charging capacity for a total bank of 300AH.
2. You did the right thing, IMHO, by using smaller batteries which won't break your back. HOWEVER, you need to be sure that they are connected together with LARGE wires -- 2/0 is my preference -- and, if possible, connect them together and use them as a single large battery bank rather than two separate banks. This is preferable for several reasons which have been discussed here and elsewhere. You can do this either by wiring them together directly, or using a 1-BOTH-2 switch and leaving it in the BOTH position.
You didn't mention a starting battery. I assume you have one and that it is independent of the house batteries, as it should be, and that it is switched separately (i.e., not connected to the selector switch for the house batteries).
The preferred way to treat such a system these days is to hook all charging sources -- battery charger, alternator, generator, solar panels, etc. -- directly to the HOUSE battery bank, and to maintain the starting battery separately using a device like the Xantrex Echocharge. This works very well.