When working to solve an electrical problem this morning, I discovered a copius amount of water in the battery compartment.

Any ideas as to where the water came from and how I can correct the problem?

 

There are actually quite a few possibilities for this one.

Do you have a sunroof? The sunroof or sunroof drain tube could be leaking.
There might be a gap in the bonding around your hatch window.
and there might be a leak around the brake lights.

Those 3 are the ones I've heard of.

 

I just had this repaired on my '06 MCS. Primary source of water in the battery box was from my going to a car wash around the corner (in between washing it myself) and buying the premium option. This includes an undercarriage pressure wash. Problem was a bad seal in the battery box. That, along with the module next to the battery, and the battery cables themselves, had to be replaced. Took the dealership about a week to repair.

I've been back to the wash once, and the battery box was dry when I looked at it last night. Reason I checked is, a couple of times yesterday, my MINI did not want to start up. I had to hit the terminals with a brass brush to clean them up. Then I sprayed them with battery terminal corrosion preventer.

 

Forgot to mention... the source of all this was my airbag light came on a few weeks ago. It was due to the module next to the battery being corroded.

 

My recommendation....
Fold the rear seat down, then pull the carpet out of the way....sit/lie down in the rear of the car while a helper sprays water around the exterior...
I would concentrate on the rear brake light assemblies, the 3rd brake light, and perhaps the sunroof.
Look a feel closely, and you should be able to find it. Please remember that the side panels on the interior of the trunk uncilp to give you acess to the brake lights....
The foam gasket on the 3rd brake light goes bad too...you could pop it out, clean it, then reinstall it...if it leaks, the water will flow around the inside of the rear, and possibly appear on the sides...that is why a 2nd person with a hose is important. Just be sure to use a shopvac to remove the water, and prime/neutrlize the rust as needed. Oem paint colors are avalable in spray cans from some vendors...I got some for mine from WayMotorWorks.com...he might not list it on the website, but like many things he sells, just ask, he most Lilly stocks it!

 

We do not use automatic car washes, so that is not the culprit. We do plan on doing a spray test sometime this weekend to check for leaks.

JumpingJackFlash - Now the airbag idiot light is on. What exactly does that module look like? Is it something I can order from an aftermarket company and install myself?

 

I have had this same issue with my 06 MCS. Here is another possibility the exterior finisher peaces around the rear glass at top and bottom are held on by clips which can also leak as in my case. I found this by removing all of the interior trim from the hatch lid and running water over it. As mention in the previous post the third break light, side tail lights,rear wiper seal, and window seal are also possibilities. 3m strip caulk is a good fix for any of these potential leaks. It does not harden like glue just makes a good long lasting flexible seal. The fuse box is the black and orange box on the right side of the battery box. What I suggest is remove the battery and try to clean the connectors as best as possible. Open the fuse box and clean there as well. These parts are only available through OEM. If the cables are corroded beyond repair then replacements will cost several hundred dollars. The positive B cables run the length of the entire car from front to back and there are two that may have to be replaced. It just depends on the damage. The air bag light will have to be reset by the dealer or some that has the proper scan tool that can manage the job. Hopefully a good cleaning and having the ABS sensor reset will do the job. Hope this helps

 

I don't think that module next to the battery is available aftermarket. Empty your boot and lift the carpet liner to see the box/module. Mine, along with the battery cables, were all replaced under warranty. According to http://www.realoem.com/, the module part number is 61 12 6 922 465. To find, click "61 Vehicle Electrical System," then "61 30 Battery."

 

Just discovered this exact same issue in Max's boot yesterday morning... it was after a particularly heavy overnight rainfall, and the right side of the boot floor was saturated, along with about half an inch of the wet stuff in the battery box. Plan to perform a "spray test" like ZippyNH recommended.

 

I think this is a very common issue with R53s. Most owners never pay any attention to the car battery until it fails. The rear hatch area has several potential leak points and one will eventually let the water in.

 

I'm not so sure this is a common issue. I never had the problem with my old '02 MCS after 115K miles.

 

Its pretty common for the water in the hatch area, this place is plagued with people who have had this problem. I still have not found the exact cause for the leak into my hatch, I thought I did, but to no avail. I would say MINI did a **** poor job of making the rear hatch waterproof, a lot of bad design work on that part of the car. I just have to make sure to open the hatch slightly and let the water drain from the weep hole on rainy days, otherwise when you lift the hatch water comes out all over the place.

 

Actually, you made me remember... I did have a small drip leak directly down the middle of the rear hatch glass on the inside. If memory serves, it started sometime in '08.

 

As unplausable as this may sound, this part

Stop buffers - MINI Part No. 51240305688

hatch004.jpg?t=1276567244

has been know to allow water into the rear hatch. It's the rubber stop on either side at the bottom. Water then finds it's way to the latch area,
hatch003.jpg?t=1276567493

and then down into the battery box......not sure if it's because they get dried out or what, but it's a cheap fix.

Water can do strange stuff at times

 

I'd bet dollars-to-donuts it's the third brake light gasket - which kinda makes the "spray test" a WOT, unless you remove all the hatch trim hiding it and the water pathways - I re-installed mine w/ some clear RTV, making sure the sunroof was vented (so when you close the door the pressure doesn't blow the sealant out) and let it sit overnight...

My "tell" was the water running out of the inside of the hatch trim panels when I opened it after a night of heavy rain...

 

my 02 mcs (112M mi )drips from the molding along the inside top of the hatch. Also rattling. I suspect the seal of the glass to the frame has broken /dried as the slamming of the hatch is quite a violent act. Was this ever covered in a recall??

 

Here is a link to a list of complaints with the NHTSA: http://www.arfc.org/complaints/2002/...per/?q=&page=1. It will take awhile for you to read through them. I don't think the rear seals had enough problems/complaints to warrant a recall.

Best way to check is to grab the garden hose and spray the backshield glass. Any windshield shop should be able to reseal it for a nominal fee. I go with Safe Lite. They are a national company and are supported by many car insurance companies. Plus you can get your services warrantied anywhere there is a location around the company. Because there was no accident, the claim would more than likely fall under the comprehensive portion of your auto insurance. My deductible is zero on that one, which is really great.

If needed, The current part number for the boot gasket is 51 71 7 132 471. The listed price is $66.38. Should be pretty easy to change out.

 

I just discovered the same problem upon trying to replace the original battery at 28,300 miles. I have a '05 Mini S with sunroof.
A significant amount of water was in the battery box. The BST cables (Trunk - front bay) and the battery fuse box have to be replaced. Of course the corrosion damage will also be corrected. Have you found out what caused your situation? I noticed that suggestions were made that this could have been caused as a result of a poor design of the hatch back, poor seals on the tail lights, or plugged drain channels in the sunroof. I am having it all checked out.

 

look at the brake light locate above the hatch window. After I tightened three screws the problem was resolved. (now if I can just figure out why the hatch area squeaks so much!!)

 

I realize this thread is a bit dated. However, as reported by JumpingJackFlash I also found water in the battery well on my '05 R53, while diagnosing a SRS indicator light that has come on inexplicably in the past 2 weeks. Who ever chances to look in a battery well :(. Anyway, I'll pursue that path. What I wonder is if anyone can tell me where to look for the Sunroof drains?
Thanks

 

i have 05 car with same issue, i also have a sun roof
changed 3rd light which i thought solved it
but just discovered its still leaking
so i will have to start looking a little deeper

 

Water migrates mysteriously, so I would also check the rear grab handle, it is also a known rust area so not bad idea to check anyways, sand/primer and touch up paint the areas where needed.

The replacement rear grab handles for 1st Gen from the dealer have a thicker gasket than before too so apparently a fix was made at some point.

Odd as it sounds, have also seen where a rear hatch rubber stopper(s) was the issue. New ones was the fix.

 

My battery compartment was filled about an inch with water however I think this might be recent due to heavy rain so nothing was corroded but My srs light did come on a few weeks ago. however I don't see any kind of module next to the battery I just have a box where all the wires tie too. it looks nice and clean no corrosion. I wonder what you meant by the corrosion was causing your srs light to come on, I would love to have some feedback or help on this.

thanks,
Bilal

 

Check the rear hatch seal and 3rd brake light first, then check your sunroof drains.

 

+1 check those rear sunroof drains.

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



Rear trim to check.

https://www.northamericanmotoring.co...ater-leak.html