[soawsome]

Battery Positive Lead Corroded

Hello All

I am hoping someone can give some advice on my cars recent problem. I have searched the forums and cannot find someone with a similar situation so I am guessing it is somewhat unique

My Car: 2006 325xi with 155k miles

I drove to work the other day with no problems. After work I went to start the car and the engine would crank but there was no combustion. My first thought was the fuel pump. So I towed it to BMW and they said the Fuel pump tested fine and that my battery positive leads have severe corrosion and would have to be rewired. They quoted me $3,000 on the job, which seems steep, plus with this kind of millage I am not sure if the repair is worth it, it maybe be better to just move on and get a new car.

Anyways I towed the car home and started ripping it apart and found that the 2 main positive leads going to the bottom of the battery compartment are corroded and separated from there terminal on the wheel well. Water must have gotten into this compartment, as there is slight surface in half the compartment

This seems like and easy fix just cut the rusted sections out and splice in a new cable. My first problem is I don’t know how to remove these terminals. They are badly rusted and I don’t want to break them. I am not sure if they screw out or just pry out. I am thinking after these are removed the wire can be spliced and I will be good to go again.

I am also wondering what these 2 leads power. The car seems to have most electrical power including power to the starter but no fuel?? I am guessing they power the fuel pump but what else do they power?

Any insight or even wiring diagrams? Also pictures of these terminals so I can see how they are removed. Even a picture of the terminals in someone’s car without the rust could help

Thanks in advance guys Cheers!

For 3k they likely want to run all new cables, this can be repaired for much less money, you just need to find a shop familiar with the battery wiring or look up the documentation its out there.

The blue/red with blue/black connector thats not connected is for when the car is transported to the dealer from the factory. (They plug in a power switch)

[Efthreeoh]

I agree with Index, any decent auto electrical repair shop can fix this for a few hundred dollars. It'll not be factory, but who cares at 155K. I checked realOEM, there are no repair terminals I could find for the main battery cables at the battery box (there are repair parts for the terminals under the hood). The positive battery lead is an available part for $149 (you could probably reuse the cables you have, just cut them to good clean wire and re-terminate them).

I'm assuming you bought the car used. To me that looks like a previous battery leaked acid and on top of water sitting in the battery tray (which you need to figure out too). Was the vent tube properly connected? I'd wash everything with baking soda, take a small dremel brush and clean up the terminals as best as you can. Buy a new positive terminal lead(s) if you need to. Reinstall everything and see what it does. I'm sure the body cables running to the power distribution box are ok, and just the terminals are rusted. Any chance the car was flood damaged? Salt water could possibly cause that level of rust, but rain water shouldn't have.

My wife's Z3 had a whole bunch of water in the battery tray for probably a year or two (I didn't notice it). Convertibles when they get old LEAK! Anyway, I cleaned up the water, added a drain tube to one of the body drain plugs, but there was no corrosion and rust in the battery tray like your car has. Water alone should not have rusted the metal like that.

Good luck with it.

[soawsome]

Thanks for the feedback guys!:thump:

I will most likely try and cut the cables behind the terminals and splice them with the battery cables. Hopefully the cords are long enough, if not ill have to add a patch cable in-between.

for these cables and current draw is there anything wrong with splicing cables in with a large copper crimp and insulating it with electrical tape? any chance of overheating the cable?

[Efthreeoh]

Originally Posted by soawsome

Thanks for the feedback guys!:thump:

I will most likely try and cut the cables behind the terminals and splice them with the battery cables. Hopefully the cords are long enough, if not ill have to add a patch cable in-between.

for these cables and current draw is there anything wrong with splicing cables in with a large copper crimp and insulating it with electrical tape? any chance of overheating the cable?

Nah, yer good. The power company does the same with 220V coming into your house.

[Millbeensaucey]

Having the same problem wondering were the two positive cables got disconnected from.