Hi acei,
Any time power is drawn from the battery and then replaced it is one cycle. Shallow cycles promote long life. Solar helps to reduce the depth of a cycle. In an ideal world a saturation charge would be the best way to recharge. The only sane way to do that is on shore power, as it takes 14 to 16 hours.
In theory I could use one bank to saturation charge the other, since I have the necessary switches in place.
Go easy on the battery bank for the first five cycles--and then be cautious for the next 15. Easy = don't do 50%--only draw 10% and no "heavy" loads. After a heavy load do some recharging right away if you can, (solar is nice for that) or at least "rest" the battery by turning off all loads for one or two hours.
Avoid deep cycles--even 50% is a lot.
