Hi big,...........need some good advice...... I've got 2 deep cycle 12v Optimas coming.
Don't know if this is good advice, but WTH. Take a discharged Optima and connect it to an automotive alternator. Then belt drive the alternator from a stationary bicycle with the wheel driving the belt. See how long it takes to charge that one battery. Multiply that by 2.
My bet is that it would take you 20 hours to charge those 2 Optimas peddling full time as hard as you can.
Now add in the discharge efficiency of a PbAcid battery and lose 10 to 20% of that energy you just worked so hard to store. Now add in the propulsion motor efficiency and lose another 20 to 30% of that energy you worked so hard to store. See where I'm goin' here?
So, the electric/human hybrid bicycle is a good machine. But use it wisely. Put the human power to the wheel and let the utility company generate the electric energy which you use to charge the battery. Or get a solar cell to charge it for you.
Back to your question about wiring. You cannot discharge 2 batteries in series while charging them in parallel from the same generator. So you will need to use two isolated generators, one for each battery. But these generators can be half size then.