[enderw88]

Originally Posted by M3 the dream

I remember messing with the battery before and the terminal closest to the frame of the car in the compartment touched the metal and sparked when the car was off.

Yeah, that's bad. Not even sure how its possible with the correct battery. Take a picture of the battery well and post it.

[98///M3]

Originally Posted by M3 the dream

Thanks a lot so far lots and lots of great ideas for me to check out over the next days. I have a lot of checking to do. Was driving today and thought of another possible thing that is causing this problem. The screw that holds the battery in place broke so the battery has a bit of wiggle room. I remember messing with the battery before and the terminal closest to the frame of the car in the compartment touched the metal and sparked when the car was off. If this happened when the car is on could this possibly short the car out for that split second. Under hard braking the battery could move forward and hit. Not a electrical scientist just curious. Once again thanks for the ideas and opinions really helpful. (updated grammatically correct version and not me rambling ideas with no end)

Fix the battery mount. Then see if it happens. If you noticed this problem immediately after you broke the screw, then I'd say it's a pretty suspicious item.

[M3 the dream]

Well before I went to work this morning I made this tester solution. As funny as it is so far the car did not malfunction at all. A few more days of driving with this and I think I will have determined the problem.

[enderw88]

Originally Posted by M3 the dream

Well before I went to work this morning I made this tester solution. As funny as it is so far the car did not malfunction at all. A few more days of driving with this and I think I will have determined the problem.

You don't need a few more days. That is a BIG problem. Maybe not THE problem, but a big problem. There should be a rubber or plastic shield over the positive terminal that prevents exactly this.

You have an unfuzed high current short that is ASKING for serious trouble. You are lucky you haven't had a fire yet.

As a stop-gap rotate the positive terminal so that it is not hanging over empty space.

[dthomp87]

also that is the wrong sized battery and its not fastened down correctly because the battery is not long enough to fit under the battery fastener.

[M3 the dream]

Found out this is the wrong battery today. I changed my oil today and as I was about to start it up the battery Coincidentally died. WTF had no problems since I had the car. Anyway, after checking out the battery it is from 2001. Getting a new battery tom. Hopefully it comes with terminal covers

[Richardsperry]

The battery doesn't have or come with any covers.
see http://bmwfans.info/parts/catalog/E3..._battery_rear/ for the battery mounting parts. It's been so long since I've looked at the battery I don't remoember if it has a insulator, but electrical tape does wonders. I once left a 13mm wrench back there, and it tried to short out. Yes the car went wild and wouldn't run. Lucky no serious damage was done.

Interstate MPT91 fits fine and make sure you ask for and get the free vent kit. YES IT'S IMPORTANT. (any group 91 battery will fit, as will a 92 but they are hard to find.) It's about $110.

[DEAFM3]

Originally Posted by Richardsperry

The battery doesn't have or come with any covers.
see http://bmwfans.info/parts/catalog/E3..._battery_rear/ for the battery mounting parts. It's been so long since I've looked at the battery I don't remoember if it has a insulator, but electrical tape does wonders. I once left a 13mm wrench back there, and it tried to short out. Yes the car went wild and wouldn't run. Lucky no serious damage was done.

Interstate MPT91 fits fine and make sure you ask for and get the free vent kit. YES IT'S IMPORTANT. (any group 91 battery will fit, as will a 92 but they are hard to find.) It's about $110.

Sorry to jack the thread, but its something about battery.

I bought interstate mpt91 and it never came with the vent kit. I asked for it repeatedly. The guy who sell batteries said I didn't need it. I told him, I'm putting in the trunk. So my question is, what happens if battery sit in the trunk with no vent kit.

[white-hot]

Proper battery + actually mounted to the car = winning

Here is the link to the diagram with parts numbers for what you need to mount the battery. Covers are not strictly needed but are a good idea. The vent IS needed. When a battery is charged it produces bubbles in each cell and the gas and any fluid it may contain needs to be safely vented/drained from the trunk. The trunk itself has a vent behind the carpet and above the battery compartment but the vent tube is very important as well.

[Jrrrrrrr]

Originally Posted by DEAFM3

I bought interstate mpt91 and it never came with the vent kit. I asked for it repeatedly. The guy who sell batteries said I didn't need it. I told him, I'm putting in the trunk. So my question is, what happens if battery sit in the trunk with no vent kit.

My PO had a brand-new BMW-branded Exide battery installed without the vent line. This battery was installed by a seemingly-professional European performance shop (according to invoice) with no vent line, which upon finding out, makes me both shake my head and facepalm at the ability for shops to maintain these cars as they get older.

I went many months into my ownership without figuring out that the vent line should be there. I personally noticed no catastrophe from venting H2 gas from the battery as it charges, but adding a vent line is so cheap and easy, you would be stupid not to if you know its an issue.

Originally Posted by white-hot

Proper battery + actually mounted to the car = winning

Here is the link to the diagram with parts numbers for what you need to mount the battery.

//Thread.

The battery will move and probably make noise when not properly secured to the car. The 90* plastic-elbow is readily available and costs around $1. The tube, which runs from that elbow to the outside of the var via a grommet a few inches from the positive side of the battery is also readily available and free if you can find a junkyard e36 that still has one. It is also easy to fabricate such a tube with hardware store stuff.

Securing or venting the rear-mounted battery is hardly a difficult or expensive repair, so this issue should be better known due to countless examples of PO ignorance and negligence.