Yes, to both queries.
Battery charging takes place in 3 basic stages: Bulk, Absorption, and Float.
Bulk Charge The first stage of 3-stage battery charging. Current is sent to batteries at the maximum rate they will accept while voltage rises to full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. Most garage and consumer type battery chargers
are bulk charge only.
Absorption Charge The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.4 to 15.5 volts.
Float Charge The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it''s main purpose is to keep an already charged battery from discharging. Voltages at this stage are typically 13.2 to 13.6 volts.
Tell us more about your energy consumption & boat use; and we can offer a little advice. Obviously, better chargers & batteries cost more - so you have to match your technological investment to your requirements.