Marine Battery Chargers

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The voltage of your boat's battery charger needs to match the output voltage of your battery. 12V batteries require a 12V charger. Same applies to two 12V batteries in PARALLEL - voltage does not double, you still need a 12V battery charger. However, two 12V battery chargers in a SERIES setup will now double to 24V, and youu2019ll need a 24V charger. Mismatching voltages between charger and batteries will end up destroying the batteries, and may even cause a fire.

Amps required depend on the size and type of your battery. A higher amp rating means a faster recharging time. For instance, 15 amps per bank would charge a battery faster than 5 or 6 amps per bank would charge that same battery. Follow the formula above to determine minimum amperage of the marine battery charger required.

Main difference in wiring batteries in series vs. parallel is impact on the output voltage and the capacity of the battery system. Batteries wired in series have their voltages added together. Batteries wired in parallel have their capacities (amp-hours) added together. However, the total available energy (watt-hours) in both configurations is the same.

Depends on how many batteries you need to charge. You need one bank for each battery on your boat (including starting battery, if appropriate).

Portable chargers work well for smaller boats, where the battery can be easily removed. Owners of larger vessels are better off purchasing on-board marine battery chargers.

If you operate your house bank between a 50 % and 85 % state of charge, as many experts recommend, and charge once daily, you should be able to return the 35 % of battery capacity by operating a properly-sized alternator for slightly over an hour. More deeply discharged batteries, or smaller alternators, will require more time.

You need a charger with enough capacity to run the continuous loads on your battery system, like DC refrigeration and lights, plus enough power to float-charge your batteries. Good rule is to have enough amperage to equal sum of the DC loads plus 10 percent of the amp-hour capacity of the batteries.