Battery box at one point was filled up with water and rusted to hell cables in the battery box. My system voltage is 14.05v when on and when off 12.85v but my car is shooting a 5DF4 code saying system voltage 9v< . Anyway to fix my problem of the wires that are in the box

 

A little bit of WD40 and a small wire brush will clean up the corrosion pretty easily. Just make sure to wear something to protect your eyes

 

Yes, as was said, I would start by cleaning all of the contact points so you have nice clean metal on both sides of contact. Then maybe a spray of battery corrosion inhibitor.

 

yikes,

Looks like water from the rear drain tubes / trunk. For the sunroof. I would check those drain tubes :

https://www.northamericanmotoring.co...-footwell.html





here is the convertible, but same issues.

https://www.northamericanmotoring.co...mpartment.html

 

My car had this problem. I drilled a drain hole in the box. I also cleaned all the contacts and all is good. At least with the drain hole it will never fill up again.after it drained I noticed a sticker over a hole that I could have just removed. Oh well. I didn't think to look under that black cap. Man that corrosion is bad.

 

Option for you is to mount in into the hatch area and use a remote battery box. Many companies make them. Safe and secure .

 

or the foam gasket around the 3rd brake light (the most common problem fir this imo)....or even the tail lights...they have a foam strip around the edges to seal them that turns to dust with age...a carwash or park on a hill....

 

Thank you all definitely going to test all the possibilities! When I get to the shop tomorrow I'll let Ya know what it was

 

Welcome, let us know how it goes.

 

Have had this issue for most of the life of my Mini. Drilled a hole in the rubber stopper to keep it drained, but I'm getting sick of the issue altogether. Today I am removing as much paneling and items I can in that hatch area to figure out where this water is coming from. The fact that Mini uses foam gaskets in places that allow water to soak the carpet and fill the battery box is just boneheaded (as I've found some other things on this car are as well).


I don't see how the sunroof drain tubes could cause this issue though. They drain outside of the hatch weather strip. So unless your weather strip is compromised, it's probably one of those foam gaskets.

 

Get to an auto parts store and get your battery load tested. It's free. Be sure it is fully charged and it top shape. Get all the connections clean, both sides. Motor on