Boat DC Alternator Chargers

Boat DC Alternator Chargers: What You Need To Know

Ahh! What a great day for fishing! But, oh no! Your trolling motor is low on charge. That’s when a dc alternator charger comes into play.

But, what is a DC alternator changer? Where should we put it? How to use it? Don’t worry, in this article, I will discuss each and everything which you need to know about boat DC alternator chargers. Without any further delay, let’s start.

Note: most links in this article are Affiliate links, see Affiliate Disclosure, thank you.

What is a DC alternator charger?

A DC alternator charger is a type of charger that takes power from the engine’s alternator and directs the power to the trolling motor batteries so that they will be recharged while the engine is running from one fishing hole to another. A DC alternator charger is the best way to charge a trolling motor battery from your outboard motor.

The charger turns on whenever the boat’s ignition key is on via a wire connected to the ignition switch from the charger. Then the power from the main battery is run through the charger and sent to the individual batteries.

DC alternator chargers are available in three different varieties in the market: DC charger for one bank systems, DC charger for two bank systems and DC charger for three bank systems. I will also discuss each of the subjects mentioned above in detail so that you can choose the best option for your boat.

How will the DC alternator charger help you?

The main purpose of a DC alternator charger is to supply power to your trolling motor batteries so that you can extend the length of your fishing trip. Having a DC alternator charger on your boat is very handy if you love to go for long fishing trips. They also come at a low price so you don’t have to worry about overspending.

How to install a DC alternator charger?

Installing a DC alternator charger is rather easy. Mount the charger then connect the cables to the desired place and it’s ready to use. The steps to install a DC alternator charger is described below:

  1. Mount the charger in a location that will allow the cables to reach all batteries to be connected in your system. If that is not possible, you will need to extend the cable to your starting battery in the next step.
  2. Find the input cable labeled “STARTING” and connect the POSITIVE (RED) wire to the POSITIVE (+) terminal on the starting battery. Then connect the NEGATIVE (BLACK) to the NEGATIVE (-) terminal on that battery.
  3. Find each output cable and connect the POSITIVE (RED) wire to the POSITIVE (+) terminal on the trolling battery. Then connect the NEGATIVE (BLACK) to the NEGATIVE (-) terminal on that battery.
  4. Connect additional output cables to the batteries as described in above step 3.
  5. For this DC Alternator Charger to function, find the purple ignition wire on the charger and connect it to the Ignition Circuit. This can be any +12v source that is only energized (powered) when the ignition key is turned on.

Picking the right DC alternator charger

As I have already mentioned, there are three different sizes of DC alternator charger for your boat. I have discussed each of them below. Now, it is your task to pick the right one for your boat.

MK 1 DC for 12 volt systems– As the name suggests, this charger is for 12 volt systems. This charger has a inbuilt LED display, along with extended battery protection. It is completely waterproof and Minn Kota also gives a replacement warranty of 3 years. So you can have a long-lasting relationship with your charger.

MK 2 DC for 24 volt systems– Two bank systems? No problem! This model is perfect for 24 volt systems. This charger also comes up with a inbuilt LED display, along with extended battery protection. Minn Kota has ensured that the charger is completely waterproof and they also give a 3-year replacement warranty. Cool, right?

MK 3 DC for 36 volt systems– Now comes the biggest of all the chargers. This charger is perfect for 36 volt systems. Again, this charger also has a inbuilt LED display, along with extended battery protection. Its completely waterproof as well and the product comes up with a 3-year replacement warranty.

Details of the MinnKota MK 2 DC – DC alternator charger

With a low-profile enclosure and a waterproof, corrosion-resistant design, this DC Alternator charger uses current from your boat’s alternator to recharge trolling batteries when the main engine is running. Master cutoff switch turns charging off while the engine isn’t in use. Experience effortless, accurate charging with up to 20 amps of total output.


  • Onboard charging capacity
  • Extended battery protection
  • Fully Waterproof and shockproof mechanism
  • LED display
  • 24 volts charging capacity (2-12-volt batteries)
  • 10 amps per battery
  • Lightweight and compact
  • Advanced corrosion protection
  • 3-year warranty

If you love long outdoor trips, then you would love this product. It helps you to charge your trolling motor batteries on-board. Besides that, the DC alternator charger also comes up with battery protection which ensures that your batteries don’t get destroyed while charging. This product is saltwater tested, its lightweight design and affordable price add to its greatness. We can’t find any reason why you shouldn’t buy it.

Click here to see the MinnKota alternator charges on

What are people saying about them?

We have seen lots of positive feedback about the MinnKota DC alternator chargers on Amazon and eBay. One customer said that it is a must-have accessory for a fishing lover. Some people say that with this DC alternator charger, your motor’s battery won’t go below 70%. If people are asked to describe the product in one word, then they would probably say excellent. We also agree with the people.

Personal experience

I have the MinnKota MK 2 DC and have been more than happy with it. The charger has added time to my fishing trips many times and continues to work great after eight years. I can not verify the listed amp rating but do notice a charger performance increase with my new motor that included a larger alternator. Also, When the key is on but the motor is not running the charger will draw from the main battery(starting battery), while I have never had a problem with this, it is something to keep in mind.

Click here to read our review of Trolling Motor Batteries


DC alternator chargers have brought a huge change in the fishing world and they are considered one of the best innovations of the decade. They are very easy to carry and you can easily install them on your boat without paying a marine professional.

With the help of the charger, there’s no need to worry about your batteries running dead. After all, worrying about your trolling motor performance can ruin an awesome day. So, get out on the water and have some fun.

Click here to see the MinnKota alternator chargers on


How To Charge A Trolling Motor Battery From The Outboard Motor?

A DC alternator charger is the best method of charging your trolling motor batteries from your outboard motor. After your main battery has been fully charged your main motor alternator output is sent to your trolling motor batteries. This method safely adds a charge to your trolling motor batteries without damaging your charging system.

Will a DC Alternator Charger Fully Recharge My Trolling Motor Batteries?

It is not likely that a DC alternator charger will fully recharge your trolling motor batteries. The main purpose of a DC alternator charger is to add a small amount of charge to your trolling motor batteries to extend your fishing day. This works because as you run your main motor to move your boat from fishing hole to fishing hole, the extra charging amps are sent to your trolling motor batteries.

What is the Best Alternative to a DC Alternator Charger?

Two options for a DC alternator charger are solar panels and wind generators. The main downside to these charging devices is that they are low output. Solar panels and wind generators are common on sailboats where large amounts of power are not required.