Months ago I lost the small nut that went on the secondary post on the positive side of my battery. I forget to purchase a replacement and ultimatly forgot about the whole thing until today. I was driving home and noticed that my Battery and "Brake" warning lights were both on. I remembered the lost nut and when I got home replaced the nut with one in my tool box from my old Honda. Lights went off, problem solved, except...
The post looks all burnt up (see pics below 800*600 JPEG about 75kb) from where I'm sure it shorted itself out. My question is what have I ruined? How bad have I ruined it? How important is it? How expensive would it be to replace? And, where could I find such a replacement?

For all you photo buffs, shots were taken with a Konica-Minolta DiMage Z2 in SuperMacro Mode. I have full resolution shots (2272*1704 JPEG about 1.5MB) for those that are interested.

 

um.. Not sure how a bolt caused that to happen, but if it shorted out your whole electrical system expect to pay a hefty price. If everything still works.. leave it how it is

 

The bolt wasn't there until a few hours ago. It is not the bolt that caused it but the lack of a bolt. So far everything is good, I just hope it stays that way.

 

yep, leave it alone. Looks like small arching, nothing to be too concerned about since you fixed the cause.

 

Is there fuses in the small container picture one on the right? If so might want to check those?

 

If everything is working then you're fine. Just some burning from arcing, as mentioned before, nothing looks like it actually melted or broke.

 

I think(could be wrong) that is the main battery fuse. if he blew that he basically will have a problem with his car starting/running

 

Yea i think that's what it is.. oddly enough i don't think my car has that type of battery mount... that or i'm looking at it from a weird angle or something, but my mount has a nut on it that when tightened it clamps around the post coming off the battery...

 

two different nuts on the same post. wow, that works as a response to your post no matter how you look at it!

anyway, sorry it's late. the nut you are talking about can just be seen in the top photo at the bottom edge of the photo.

 

Thats bcause of the faulty connection , its like removing and connecting a power cord many times you had a constant spark in there !

 

this sounds pretty low, but, bring it to the mitsu plant =X!!!!!!!!

 

Nah, I wouldn't do all that. Like others have already said, it seems to be burn marks from arching. Long as nothing is broke he should be fine. I'd at least wait till something was actually broke. No use in wasting all that money for the dealer to say "we put a new bolt on your battery, you're good to go now."