Thread: Battleborn lithium battery: Melted trolling motor wires

Originally Posted by Atimm693

The cause is high resistance somewhere in the circuit. Could've been the lug, the small wire, bad brushes in the motor, etc.

Once the resistance goes up, voltage goes down, amperage goes way up, and things start cooking.

I have a friend who used the minnkota battery box setup on his pontoon (with a wet battery) and it did the exact same thing a few years ago. He now has a standard box and a 50A breaker on the lug. He hasn't had an issue since and nothing else was changed. I suspect maybe the wire or connections made as part of the box were high resistance. (possibly even the 60A breaker itself?)

A 45-50 Amp draw will generate alot of heat in a small amount of time!

Chris

Thanks NCkenner. I am going to get a standard box. I think the Minn Kota box was the problem. I just cant believe how much they charge for the box and it is a chincy piece of plastic with a few hidden wires.

I will now be able to check all connections each day before launch.

Its too late now but if you had suspected a problem a voltage drop test would have pinpointed the problem. Like a bad connection or corrosion inside a lug where you can't see it. This can happen.

Your battery box wiring is definitely your problem, the heat is always going to start at or very close to the bad connection( most resistance). Hopefully it didn’t melt the connection in battery.

Time for a time out and troubleshoot.
I would recommend complete disconnect from the battery, a known good meter set to ohms, and check for continuity between the positive and the negative leads of the boat. Do the same to the trolling motor, and if necessary, any and all accessories.
Sure, it could possibly have been a loose connection at the negative, but I say find the culprit and eliminate the gremlins before going to bigger things (Like cables, battery, bigger hammer, etc.).
I would also be concerned that circuit protection did not do right. Might be a good time to reevaluate/update your protection. If you do decide to update your protection, I highly recommend disconnect switches for each battery, buss bars as needed for cleaner distribution, and fuse/breaker protection close to your batteries to keep your boat wiring from going up in smoke!

While GrandPoohBah brings up a very good point about checking everything, I would not be at all surprised if everything checks out just fine and the problem really did lie in the connection/wire size/batterybox/etc from MinnKota. Many manufactures are notorious for cheaping out and under sizing components. They size them for "average" use and not for continuous full power usage. Car manufacturers will do that just to save a few pennies on each car. After you have checked everything out and are putting it back together, there is no downside to going up one size in all the components (other than an extra couple of bucks in material cost).

I had a 35lb motor guide transom mount. Clips on the wires. On a light boat, a canoe if I remember right. Had a fairly long run into the wind to get back to the ramp. Not long into it I smelled the same thing you smelled. Wire at the clips was melting and I still had a long way to go. Turned it down to 3 out of 5 and it ran the rest of the way without issue. I know the issue was the clips not making a solid connection. Switched to lug connection and it made no difference. Wire was too small and cheap insulation. Sold it with a small boat a few months later. Stupid for manufacturers to squeeze a nickel that hard on something that simple. New marine grade wire and a size bigger on the main feed if you’re gonna use it on high for extended periods. I stay on my 70lb TM for 7 hours and the wires and connections never once even get warm. Hope you figure it out.

Another sure fire test for others with similar setups as Big D is posting here would be to use a known good meter with an amp clamp on it that reads DC amps. Your better amp clamps read AC and DC, but some cheaper models only do one or the other. Have someone, if needed, to put the trolling motor (Or what ever you are testing) under a good load as you check amp pull with the clamp/meter around the cable in question.
I hear what some of you guys are saying about manufacturers trying to "Cheap Out", but there are standards and electrical codes and approvals that the manufacturers must comply with.
BTW - just how long are your cables?