Melted screw fitting on a CTEK250 Dual

[mudski]

So whilst the a/c was being attended to today at the workshop I decided to crawl under the pax side of the dash and look at my CTEK 250. Dunno why but I did. Luckily. I found that the screw fitting with the plastic grip on it that holds the wire to the CTEK must have gotten hot at some stage as the plastic bit on the screw had melted. The connection in question is the alternator +ive on the CTEK.
Now I am unsure when this might have happened. Two days ago I had removed the aux battery and zip tied the battery terminals securely. But had not disconnect anything from the CTEK. I'm not sure if this might have done anything though.
I've looks at the user manual and can't see anything as to why.

Any idea's?

[GeeYou8]

Have you checked the connection at the crimp & screw, a high resistance will cause it to get hot.
Graham

[the evil twin]

Have you checked the connection at the crimp & screw, a high resistance will cause it to get hot.
Graham

Wot he said X 2

[mudski]

Have you checked the connection at the crimp & screw, a high resistance will cause it to get hot.
Graham

Check it for what? Lose wire into the wire terminal? Lose connection from terminal to CTEK? Wire to terminal is good. I did notice the wire terminal that connects to the CTEK was a bit loser that it should have been. While it was still attached fairly firm, I could move it. Where as the other three I could not. I thought it may have come lose from the heat in that terminal, but maybe not? The lose terminal caused the heat?

[the evil twin]

snip... I did notice the wire terminal that connects to the CTEK was a bit loser that it should have been. While it was still attached fairly firm, I could move it. Where as the other three I could not.
snip...The lose terminal caused the heat?

Yep, that's 99.9% what it would have been.

You won't usually notice it with low current without a Temperature Gun but get up above 10 to 15 amps and the temp from a couple of ohms will skyrocket and melt placcy no worries

[GeeYou8]

It wouldn't even need to be a couple of ohms, 0.01 ohms at 50 amps would give 25 watts of heat which is about the same a soldering iron, enough to melt the plastic, at 70 amps 49 watts.
Graham

[mudski]

Thanks Graham and ET. I don't know if its just me watching the volt gauge more now but I have noticed the volt reading for both batteries higher.
20160923_130007 (Medium).jpg
Battery 2 is the concerning one. Maybe its just me watching, or noticing the gauge more.

[the evil twin]

Hmm, looks pretty good to me.
Nominal for the Ctek is 14.4 volts @ 25 degrees and I'd call the gauge at 14.6 maybe 14.7 which is fair enough.

Funny thing about cars tho is they are all different and you are right to be wary of something that 'changes' for no apparent reason.

I would just keep an eye on the voltages at this point.