Replaced key fob battery - photos
 

I know this is an old thread, but I just did the battery replacement and had a few photos and comments to share. Here are some photos of my key fob and the battery replacement. I ordered the new battery from Mouser Electronics.

Part info:
658-VL2020-1VC
VL2020-1VC
Panasonic Coin Cell Battery
3V 20mAH 2 PIN VERT

The metal contact blades of the battery did not match the BMW stock key fob exactly, so I had to modify the leads slightly. I scored the blades with an exact knife and put a little solder and flux on them. Using some thin stiff wire, I soldered new leads onto the batteries + and - blades. The new leads were then bent with needle nose pliers to fit through the circuit board, and then soldered to the board. See the detail in the second photo.

Then I trimmed the original blades to fit inside the key fob. Finally, I glued the key fob back together and then followed instructions from this forum on reprogramming the key fob to the X5.

The battery was $4.72 from Mouser.com. BTW the photo on mouser.com of the battery was incorrect. The blade leads did not match the photo. Either way I think you'll have to modify the leads a little to fit the battery in perfectly.

Great add on info. It would be helpful to have a picture of the batt in the circuit before the mod! I'm trying to figure out which leads you're referring to? There is a thin short round wire and then there is the flat blade with holes in it. Were any of these part of the original keyfob setup? You didn't solder to the batt surface, correct?

Yeah I should have taken a few more photos. The battery from Mouser.com is here:

No, I did not solder directly to the battery. The flat leads (blades) you see in my photo were already attached to each side of the battery. They both extended out one edge of the battery. So I took an exacto knife and scored the blades just at the point where they extended past the edge of the battery. This way I was able to get a good solder connection to them with the stiff wire. Then I bent the wires to fit through the - and + through-holes in the circuit board.

There used to be some photos of a replacement here. but the photos have gone missing.

In the photo below, you can see the original metal blade arrangement. The + blade has a half circle shape and then bends downward to go into the board.

Don't bother trying to solder onto the battery. You may heat it up too much if you're not careful and it will short the battery internally. You may get a small "thermal event" when the battery shorts out!

Guys just save yourself time, money and of course the fear that you may permanently damage your key from doing this job incorrectly and just send it to the guy in the link below. He repaired my key (after I failed) in just a few days, and he says those batteries that we are buying are not as good as the OEM battery that came in the key. He also added that 95% of the time the battery is not the culprit, also note that he repairs the GM module also, I highly recommend this guy! :thumbup:

BMW General Module 5 (GMV, ZKE V)

That's a good alternative. In my case the battery in the key fob did the trick.

So did mine...for about a week..lol!! Apparently I fried something when I tried to solder in the new battery, well do yourself a favor and bookmark his link, his prices are very reasonable.

Great info Romeokc and Flatlander. Although I don't have any issues other than needing a second key since my car came with one key only, this thread is a definite subscription.

+1 on the key repair guy (Scott @ w.BMWGM5.com), did great and fast work for me as well (our key would work, then not, etc.)

OK so how do you get the key apart?

You don't (delicate electronics too risky to break)

If yours isn't charging then you would send it to Scott @ GM5.com like above, or get a new master key from the dealer @ $185.