54, a 2A charge will maintain a battery that's not used frequently, without boiling the water away. To actually recharge a low battery, a 6 to 10 amp charge is better. Once the battery is up to full capacity, then cut back to the 2A maintenence charge. High-rate "boost charging" is rough on batteries. I use a "smart charger" on my boat batteries, one that cycles on and off as necessary to keep the batteries hot without cooking them.
Jerry
