A battery charger upgrade is an easy and rewarding project that can be done to any boat.  Whether you keep your boat on a trailer, lift, or in the water, having the batteries topped off at all times will make sure you never miss a trip from a low or dead battery.  In this article we'll discuss how to add a battery charger to a small trailer boat. Most larger boats already have battery chargers anyway. 

Picking out the right charger

The first step is to figure out how many banks you have.  A "bank" is an independant battery, or independant group of batteries that are all connected. Small outboard boats will generally have a single bank or two banks.  Some twin outboard boats may have 3 banks.  If you have 2 bansk then you'll need a 2 bank charger, 3 banks you'll need a 3 bank charger, etc. 

Next figure out what kind of batteries you have. These will generally either be Lead Acid or AGM. Make sure you choose a charger that is suitable for the kinds of batteries you have.  Check out this Marinco 6amp Charger, you willl see in the specs it can handle Flooded (Lead Acid), AGM, or Gel batteries. Most chargers have similar capabilities. 

What sort of amperage do you need?  Without getting too technical, if your boat is going to be used once a weekend, or generally be plugged in for a few nights before use, then you can get away with lower amperage. If you have a trolling motor battery bank, and routinely run your batts all the way down while fishing and only have an overnight to charge them then you'll want a high amperage charger.  Chargers range from 5amps up to 40amps or more. 

Finally, on a small outboard boat you'll want to get a waterproof charger. Most compact chargers are, but just double check when buying to make sure it is waterproof.  It will be clearly labeled in the specs if it is, like this Minn Kota MK315D Charger.



Mounting the charger in your boat is very easy.  They practically come pre-wired.  Most will have a set of charging wires per bank.  These wires will generally have ring terminals already installed that will fit right on the battery posts.  Check out this ProMariner ProMar 10Amp Charger to see what we are talking about.  The input side of the charger normally has a household style 110 Plug that will fit a normal household outlet.  You can see one pictured here on the Blue Sea 7605 BatteryLink Charger. 

These chargers are generally meant to be mounted to a vertical bulkhead using screws.  This 10Amp Marinco Charger shows this well.  You'll want to mount them in a dry place, such as inside the center console.

To finish off your installation we recommend installing a thru-deck fitting for the charge cord.  Most of these are proprietary to fit the shape of the plug, so buy the same brand as your charger.  Here is the plug socket Powermania offers - Powemania Plug Socket


Once your charger is installed you simply plug in your boat to a normal 110 socket to keep the batts topped off. 

Recommended Parts for DIY

Single Battery Bank

Two Battery Banks