How to Choose a Battery Charger for Your Boat

There are a lot of different battery chargers out there. With so many choices, how do you know which one will work best for your boat? I checked in with our Product Management team to learn more, and got some great Q & A for you!

First things first…

What does a battery charger do?

When boats are out on the water using battery power to power lighting, radios, depth finders, trolling motors, and more, batteries become drained and must be recharged when the boat returns to the dock.  A battery charger connects the boat’s DC battery/ies to AC onshore power and uses that power to recharge the battery/ies to full capacity.

What does a charger’s amps refer to?

Every battery has a rating called amp-hours, which is the amount of amps it can put out in an hour.  When the battery is at full capacity, its amp hours are at its highest level.  As the battery drains, the amp-hours decrease, so a 100 amp-hour battery drained to 50% capacity has 50 amp-hours remaining.  Battery manufacturers usually recommend that batteries not be drained below 50%.

Similar to batteries, battery chargers are also measured in amp-hours.  In the case of chargers, the amp hours refer to how many amps the charger can transfer to a battery per hour.

How do I know how many amps I need my charger to be?

To determine which size charger is needed, you must figure out how long the charger will need to run in order to charge the battery to its full capacity.  It is recommended that battery chargers be run for no longer than 10-12 hours. 

So, if our 100 amp-hour battery is drained to 50%, it needs to be charged with 50 amp-hours.  If we use 10 hours as the maximum amount of time the charger should run, you simply take the amount of charge needed (50 amp-hours), divided by the max hours we want the charger to run (10 hours), and we are left with 5 amps.  This is the smallest charger that would be appropriate for the application.

Can I use a higher amp charger than the application calls for?

Absolutely, it simply means the battery will charge faster.  There is no harm in using a higher amp charger than the application calls for.

Can I use my charger to charge more than one battery at a time?

It depends on the model.  Each charger is designed to charge a specific number of batteries.  This is referred to as its number of banks.  A single bank charger can only charge one battery at a time.  A dual bank charger can charge two batteries at a time, and a triple bank charger can charge three batteries at a time. 


Have more questions? Give our tech, Scott, a call and he’ll help you out.

To see all the battery chargers, maintainers, and booster cables Del City has to offer, click here.

Posted in Batteries, Battery Cables & Accessories, How To, Marine.