Most high-end battery chargers will also charge a lead-acid battery. Some examples of this are the Great Planes Triton, the Schulzes, and the Orbits. The charge rate is usually limited to about 5 amps on these chargers, so they will take a long time to charge high-capacity field batteries.
A better choice is to use a dedicated lead-acid battery charger. Be sure to select a good quality battery charger which includes an automatic cutoff feature. These battery chargers will avoid overcharging and "boiling" your battery and subsequently causing early battery failure.
Vector Manufacturing makes good battery chargers for this purpose. They use switching power supplies, digital voltage readouts, and a multi-stage charging algorithm for faster charging. The VEC1088 will charge at up to 12 amps, and the VEC1092 will charge at up to 35 amps.