Just bougth a new boat with this charger. Just had it replaced and replacement has quit working. Just continually flashes yellow lights. Never goes green and batteries dead. Dealer is telling me they never have any trouble with these. Anyone have any experience?

If your batteries are below 8vdc the charger won't work. Also if your battery voltage is that low they are toast.

Yep, i could see 1 being bad; but 2??? Nah, you have something else wrong with the setup.

Bad wording. Batteries aren't completely dead. They would deploy or store my tolling motor but didn't have enough power to run it. Remote would show no battery power

What model of MK charger do you have and what batteries? Is the mode set for the proper battery type? How many hours have you left the charger plugged in?


If you have a 3 amp per bank charger, it’s going to take awhile to charge up the batteries. If you have a 15amp per bank, it’s gonna get them charged quickly. We can most likely figure it out, but give all the specs or post pics.


Sounds like you have an Ulterra, 24v or 36v? Are you 100% certain that it’s wired correctly, dealerships make mistakes. Best (easiest) thing you can do, is post a picture of your batteries and someone can confirm if they are wired properly.

Still doesn’t answer the question What is your battery voltage? 3 batteries at 8 volts will show 24 volts but squat for amps. It will also turn on a 36v tm but not fully function properly.

Digital Charger MK 315 D - 3 bank x 5 amps. Running Ulterra 36 volt with three 12 volt batteries. I keep the charger plugged in all the time. Just didn't check the charger before I went out yesterday. As mention the motor would depoly and run for short time then show low battery on the remote. I'm going to crawl in the console and get some pics.
Thanks for all the input.

Skip the pics and check battery voltage.

A flashing RED LED indicates an error. A solid YELLOW LED indicates the charger is in Bulk charging. A flashing YELLOW LED indicates the charger is in Absorption Mode. A flashing GREEN LED indicates battery is fully charged, in Maintenance Mode and ready to use.May 4, 2023

https://minnkota-help.johnsonoutdoors.com/hc/en-us/articles/6301939787031-LED-Lights-on-Digital-Chargers-2010-current-#:~:text=A%20flashing%20RED%20LED%20indicates,Mode%20and%20ready%20to%20use.

7 - Absorption Charging is when the battery has reached ~80% of its capacity and begins to lower the input current to the battery. This is sometimes known as the "cool-down" cycle. 8 - Evaluation Diagnostic is the last diagnostic mode to ensure the battery is at its optimal health.

go buy a load tester and test the batteries with it, they are still charging with flashing yellow, I used to have the same charger but 10a per bank

Yeah, the voltage would be good to know. But so would seeing if the charger was actually hooked up to the 3 TM batteries and if the TM was wired properly.

2 possibilities: bad battery or it’s wired improperly

Guys it's going to take a long time @5amps/battery to charge low battery. If they are below the threshold of the low voltage of the charger, as mentioned the charger will not start charging.

You do need to set these chargers up for the specific type of battery you are using and that would be for each bank, make sure of this. If the battery's are to low or dead, when you first plug the charger in, it won't prompt you on the setup of each bank...

You got to find out if your battery's have good voltage to start with. The main thing here, a really low battery and one that is setup with your charger, is not going to charge over night @ only 5amps. I have agm batteries and the 10amp version of the mk charger and if I run mine down, it takes between 12-14 hours for the charger to go green.

MK 315D does not have battery settings. Good for wet cell and AGMs only per Minn Kota. They will not work if battery is at 3 volts or less. Happened to me once and I had to hook up the manual charger. No problems once I got the voltage up.

I had the 330D and same, start battery got drained once and had to use the truck to jump over to get the voltage up. motel I was in didn't have a charger handy for some reason. lol