Good that I got your attention. That relieve me from potential legal liability. Let me just say I am a professional and being so can be held to higher legal standards. It is not just me that warn others of potential harm for giving advice. This is one excerpt of one other member's disclaimer that you are solely responsible for your own action:

"DISCLAIMER: I IN NO WAY AM RESPONSIBLE FOR WHAT YOU DO TO YOUR OWN VEHICLE. BY EVEN TAKING THIS INFORMATION INTO YOUR BRAIN YOU RELINQUISH ALL RIGHTS INFERRED, IMPLIED, OR ASSUMED THAT I MAY IN ANY WAY BE AT FAULT FOR AN ISSUE YOU INCUR WITH YOUR VEHICLE. THIS IS FOR INFORMATIONAL PURPOSES ONLY. "

I will not comment further on any of your posts hereon.

 

Awesome. So back to my questions. What could cause this excess heat?

 

Also FYI, I have not done any mods to the car in the last 12mo. Pulley was about 3 years ago. Only electrical related mod was installing oem driving lights about 2.5 years ago.

 

I am thinking that if you still have power from the battery then you were not the cause of the melting. I would think that to get that hot there was a good short the should have popped the main fuse. Either that or a heat shield got moved and the header heat melted the part.

If you watched the video you can see that you either have to be an Elf on the Shelf to get to the starter or have a whole lot of patience. A shop would probably pull the drive shaft so one could only imagine the labor cost involved.

If you have everything checked out on top, the last thing to do is check the connections at the starter itself. If you do not even get a click when you turn the key then either the key is not sending a signal, the lead to the solenoid is not in good contact, or the solenoid is shot. You would need to get a test probe lead on the solenoid and then have somebody turn the key. Have the trannie in neutral or park so you don't have to worry about an axle spinning around. If you have voltage, then chances are the solenoid is bad and you need a new starter. If you can reach the leads then after disconnecting the battery, loosen the nut, wiggle the wires around, and then re-tighten.

It appears that Modmini had a helper as well.

I can squeeze the crap out of a buffalo head nickel, means I am cheap, but even though I like to save money there comes a time when I just do not have the patience to put my big hands down into the space that Mini designed for an elf. I have also learned that there comes a time when it is time to take the car to a pro.

 

Ok folks so good news! The replacement jumper post and casing I ordered came in today. I filed down the corrosive burrs on the negative cable and cleaned off the other terminal end as well. After connecting both cables to the new post and tightening it down pretty good, i reconnected the battery and BOOM - engine engine started up fine!

Went for a drive around the block and turned the car on and off a few times
- fired up like normal.

Soo now the question is how do I confirm that the excess heat issue is solved? And what caused the corrosion in the first place? From what I've gathered in reading about battery terminals, the corrosive burrs could have caused the excess heat bc they wouldn't allow for a proper seal with the other terminal.

Is there a way I can test for excess resistance? Thanks all! So far this has been a good learning experience - really appreciate most of your thoughts/patience and advice

 

Yes a loose connection can cause extra heat under load. From looking at your picture it dawned on me that the header is to the left and there is no heat shield next to the air box. That appears to be an aftermarket air box, how was the terminal post attached?

 

The terminal post slides on to the air box using the flanges on the side of the air box. I was wondering whether that might be the cause of the extra heat, but it's a well reviewed/popular aftermarket unit and if it was melting the terminal posts id think there would be plenty of cases of this by now. See pic attached

 

Been watching this thread, glad you got it resolved!!!

To answer your questions (from the perspective of another DIYer. I was an electrician many years ago, but I did not sleep at a Holiday Inn Express last night):

For the heat issue, just keep an eye on things. Plastic starts getting that sheen after a heat cycle. IIRC, you should be opening the bonnet at least every week to check oil/ make sure that the bonnet cables stay free anyway. While you're under there, take a gander at this area.

Origin of the corrosion: I'm going to guess a feedback loop of sorts. Cable loosened up a bit due to NVH, or was a touch off from proper torque, or gremlins, or N. Korean spies, or something... this caused very minor arcing which lead to corrosion. Wash. Rinse. Repeat.
There's a very good chance that the only "fault" of yours in this area is not looking at it occasionally (and how many of us do?). Let's face it, we've all seen battery terminals on traditionally placed batteries that look like little puffballs due to all the corrosion that's occurred.

Finally, resistance. I would get a longish set of quality jumper cables and connect to the battery (just the one terminal... unless you're wanting fireworks). First test your resistance from the loose end of the jumpers to the battery cable in the boot to get an idea of any added resistance. from there, take the loose end w/ you to the bonnet area and measure impedance to the terminal that's caused you so much trouble of late, and finally measure to the other end of the cable that exits this terminal.
I don't have MINI specific numbers, but I will say that a similar test in stereo systems I've installed in the past usually net results of <= 1 ohm to the terminals on my trunk mounted amplifiers. Unless someone chimes in otherwise, I'd guess that you don't want to see more than 2 ohms of resistance on your mains line.

Anyway, keep my disclaimer in mind (not due to higher legal requirements of a pro, but, rather, because I have a 50/50 chance of talking out of my @$$. Glad to see you got it sorted w/out needing to buy a starter!!

 

This is valid, people think that because it is a 12 volt system it won't hurt you, but it is current that kills, not voltage.

Always disconnect your ground at the battery first, it stops the rest of the car's chassis from being one giant grounding circuit. This will minimize and/or stop the chances of shorting something out, damaging components, or hurting yourself.



As far as the melting, corrosion causes resistance to go up big time, resistance in the circuit generates heat, heat melts your battery terminal box under the hood. Pretty simple and it looks like the melting was internal from your picture so I would tend to rule out the external heat sources. In my internet opinion the marks on the ring terminal you posted look like arc scars, not rust corrosion. But take that with a grain of salt because it's just me guessing from afar.

What caused the corrosion? Age, environmental contaminants, someone leaving the nut loose, the nut backing off over time and not being checked, the wire corroding at the ring terminal, etc. It could really be a million things. Clean it all up, check resistance in the wires (dead circuits only!) and see how it goes.

I had an issue with my F250 where I was getting fluctuating/pulsating lights. Turns out the signal wire from the alternator had corroded where it was soldered into the feed line at the factory. As a result, the resistance went up and voltage went down, which made the truck think there was a load on the charging system and it upped the alternator output. That increased output was enough to overcome the increased resistance and the truck would reduce the voltage until the resistance took over again and repeat cycle at about 1 Hz. It was factory wrapped wiring and never opened until I repaired it. What caused it? Your guess is as good as mine beyond "moisture".