IMHO
There could be a few things going on here.
- You cranked the engine more than normal
- The negative cable might not have been properly tightened
- There might be some corrosion on the terminal.
- You never feel it right after so much cranking and it always gets that hot
Reasons
- Per your statement you did a lot of cranking. IMHO cranking should be in short bursts, like a second or two at a time
- If you routinely disconnect the terminal perhaps you did not get it tight enough when you put it back on. Loose connection =resistance= heat
- If the terminals are continuously in contact little to no chance of corrosion buildup. If the terminal is removed the neg post and the terminal can/will build up corrosion
- Self explanatory, it's normal, you just never noticed it before.
I suspect that there is no electrical issues as that would melt other wires before getting the battery terminal hot.
Easy to check
With neg terminal disconnected and EVERYTHING in the car off, door shut etc.
Check voltage between the neg terminal Al and the negative battery post.
Should read the same on your meter as if the leads are not touching anything.
If it reads higher you have something consuming current. (Modern radio with a built in memory etc)
You can test the amps the same way. But if it is a large load you might blow a fuse in your meter.
