Trolling moter plug and receptacle melted

Took the boat out today and fished about 7 hours. 7-8th time out this year with no issues. Get back to the dock and loaded up. As usual, I went to disconnect the TM plug but it wouldn’t turn. After wiggling it around, I got it unstuck and disconnected. Saw both the receptacle and plug (+) plastic had melted (Marinco 30amp/125v three prong). The plug did not look charred, though. The connections on the back of the receptacle were tight and not melted/deformed. I think the (+) connection inside the receptacle got weak, making a bad connection although that usually shows up with arcing. The motor ran fine all day (2018 MK Ultrex). I had in on high for a while (20-30 mins) while navigating a shallow river. The MK circuit breaker did not pop but I think is either a 50 or 60 amp (forgot to look when I got home). Finding out that this model receptacle is a bit hard to get (305CRR) but managed to locate one online.

Anyone have an issue like this? Have not had any other problems but don’t usually run on high very long.

Do yourself a favor and replace it with the best receptacle on the market.
https://www.batterymart.com/p-027-0004-kit-battery-tender-dc-power-connector-kit.html?msclkid=f9e061ece3cc1f1f4c7e036d90bd0f22&utm_source=bing&utm_medium=cpc&utm_campaign=*DSA%3A%20All%20Webpages%20-%20JF&utm_term=batterymart&utm_content=All%20Pages

Battery Tender Trolling Motor Plug

A 30 amp plug seems awfully light for an Ultrex. I don’t know how many models Ultrex has but I’ve only seen an 80lb and a 112lb, both would be drawing 40 amps or more at top speed.

I have the 80lb model. Have an 80lb terrova as well. Both boats I’ve had them on (this Skeeter and a ’16 Lowe) had the 30 amp TM receptacle set up. MK shows max draw at 56 amps but that is under max load, I believe. But it’s difficult to measure on these TM’s using PWM. But when I replace the receptacle and plug, I’ll take an clamp-on ammeter with me and run it on high to see what it shows just for giggles. Might have something going on with the motor for all I know.

HMoshier wrote:

I’ll take an clamp-on ammeter with me and run it on high to see what it shows just for giggles.

You’ve got a DC clamp-on ammeter?

HRG

Hot Runr Guy wrote:

<div class=”d4p-bbt-quote-title”>Howard Moshier wrote:</div>
I’ll take an clamp-on ammeter with me and run it on high to see what it shows just for giggles.

You’ve got a DC clamp-on ammeter?

HRG

Klein CL390 perhaps?

Huntindave wrote:

Klein CL390 perhaps?

Niiiice! HRG

Hot Runr Guy wrote:

<div class=”d4p-bbt-quote-title”>Howard Moshier wrote:</div>
I’ll take an clamp-on ammeter with me and run it on high to see what it shows just for giggles.

You’ve got a DC clamp-on ammeter?

HRG

Yes, a standard clamp-on ammeter that I used while working on bikes to check starters and their draw. Set it to read and save the max amperage. Nothing fancy but gets the job done. Was also useful in determining parasitic drain from various systems.

the trolling motor receptacles that come standard on many boats are inadequate for the load modern trolling motors can draw. it’s amazing the ways in which even premium brands under-rig their boats in certain areas.

once i started running 36v i had to replace the plugs on three Tuffys, two Skeeters, and a Lund. my current boat is direct-wired, so no plug.

this 70A from Marinco does the trick nicely. 64 bucks on Amazon.
Marinco 70A

MK designed a plug rated for 60 Amps. https://minnkotamotors.johnsonoutdoors.com/accessories/trolling-motor/plug-receptacle-mkr-26

Michael C. Winther wrote:

the trolling motor receptacles that come standard on many boats are inadequate for the load modern trolling motors can draw. it’s amazing the ways in which even premium brands under-rig their boats in certain areas.

once i started running 36v i had to replace the plugs on three Tuffys, two Skeeters, and a Lund. my current boat is direct-wired, so no plug.

this 70A from Marinco does the trick nicely. 64 bucks on Amazon.
Marinco 70A

I’m curious. The max amp draw on a 80 lb. thrust 24 volt Minn Kota trolling motor is 56 amps while the max amp draw on a 112 lb. thrust 36 volt Minn Kota trolling motor is 52 amps so why would you need to replace plugs when you started running 36 volts systems? According to the specs, you’d need higher amp ratings on your 24 volt trolling motors?
What size circuit breakers have you been using on your 36 volt systems?

I ordered a Marinco replacement plug and receptacle before finding out about the MK MKR-26 (which I also ordered but the company sent the wrong one). So, I installed the Marinco model so I could fish this weekend. Using my clamp-on meter to check the amp draw, the max I read was 48 amps on high bypass (speed 10) from a dead stop. It gradually lowered as the load dropped a bit. One thing I hadn’t noticed initially was that the plug and receptacle (+) were wired to the smallest tab on the plug. Don’t know if that contributed to the plug melting but I moved the (+) lead to the next tab which is slightly bigger. I should have the MKR-26 by the end of next week if the company ships it to me tomorrow.

I melted one just like you did years ago. This occurred after I upgraded my trolling motor from a 12/24 volt Minnkota to a straight 24 volt Motorguide Tour 82. I ran new wires to the batteries and upgraded the plug and receptacle to higher amps, 30 or better if I remember correctly. A good way to know is to go higher amp on plug/wiring/receptacle than your inline circuit breaker. I have always run 6 gauge welding cable wire for my trolling motors. It is a bit heavy, but very low resistance so you absolutely get the most out of your trolling motor and batteries. This wire is available at welding supply shops.

Michael C. Winther wrote:

the trolling motor receptacles that come standard on many boats are inadequate for the load modern trolling motors can draw. it’s amazing the ways in which even premium brands under-rig their boats in certain areas.

once i started running 36v i had to replace the plugs on three Tuffys, two Skeeters, and a Lund. my current boat is direct-wired, so no plug.

this 70A from Marinco does the trick nicely. 64 bucks on Amazon.
Marinco 70A

This 70A Marinco plug is top notch. Not sure why you’d waste your money on anything else.

ranger680t wrote:

This 70A Marinco plug is top notch. Not sure why you’d waste your money on anything else.

The Marinco 70A is what Lund supplied for my transom TM, I just wish it had a positive retention method like the new Minn-Kota setup.

HRG

Mileage may vary I guess. I certainly have never had problems.

ranger680t wrote:

This 70A Marinco plug is top notch. Not sure why you’d waste your money on anything else.

Waste of money for the positive retention provided by the Battery Tender connection? I think not. Largest diameter connector post on the market, with the largest amperage rating presently on the market. Positive retention so the plug can not be removed or fall out, unless the twist locking knob is rotated by hand to release the plug.

Attachments:

1. 

   trollplug.jpg
   

I have heard of that plug melting under high loads before. Go with one of the higher rated plugs mentioned above.

Karry Kyllo wrote:

I’m curious. The max amp draw on a 80 lb. thrust 24 volt Minn Kota trolling motor is 56 amps while the max amp draw on a 112 lb. thrust 36 volt Minn Kota trolling motor is 52 amps so why would you need to replace plugs when you started running 36 volts systems?

ha! i suppose correlation is not causation?
thinking back on it, the in-line circuit breakers kept tripping because they were too small as well. super annoying. remove/replace them with bigger ones and then the plug fried. also replace that with bigger and finally all was well.