if you have 700 Ah and can charge it at .3C you would want 210 continuous, hot, at a reasonable charging RPM (not 3000). While the Odyssey batteries might be good, the Lifeline AGMs I have regularly absorb .5C. I have an Electrodyne alternator producing 280 amps at 26V or a bit over 7KW. When my 440 Ah (@24V) battery bank is down 50%, it will absorb around 220 amps, the Electrodyne will produce this (and more) at 1700 alternator shaft rpm.