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-   -   replacing battery in key fob.... (http://forum.e46fanatics.com/showthread.php?t=451510)

jason 77 03-08-2007 05:48 PM

replacing battery in key fob....
 
Ok so here is my first attempt at a detailed "DIY" thread, also if you mess up your own key trying to do this don't yell at me!:argue:

So I have the 2 key fobs that came with my car when I bought it used. One I use everyday and the second one has had a dead battery since I got the car. When I called the dealership they wanted like $260.00 for a new one. I did a search around here and found you could get deals and what not and possibly get it down to around $90-120 bucks.. still way too much in my book since I already had a working key.

After seeing a thread on here where another member had taken apart a key fob from a car he had already sold I decided what the hell the key was already dead anyways...

Here is the key before I tried anything..

http://img252.imageshack.us/img252/6...0277od5hb4.jpg

I then proceeded to take a matt knife and xacto knife and basically carefully cut the key open along the seam where the top and bottom joined up.

http://img249.imageshack.us/img249/5...0278au0kr7.jpg

Next I took a small chisel and broke the spot welds on the battery that connected it to the rest of the circuit board.

http://img249.imageshack.us/img249/3...0279nm2no3.jpg

Once I had the battery out I looked at it and took the model number "a panasonic VL2020 3v" I found the exact same battery on mouser.com for $4.73. Once I got the battery is was a simple matter of soldering the new one in and making sure everything fit back together.

http://img252.imageshack.us/img252/6563/img0285be9.jpg
http://img408.imageshack.us/img408/7056/img0290mz7.jpg

Before I glued it up I rubber banded the thing together and went out to my car to see if I could program it.

Put the working key in the ignition. Turn to position 2 for like 1 second then back and remove the key.

Press and hold the "unlock" button then press the "lock" button 3 times, you should hear all the locks cycle through.

Now take the non working key and press and hold the "unlock" button then press the "lock" button 3 times.

Then turn the ignition on and off again to end the programming....

I took the car for a drive to charge up the battery. Once I was certain it was all working I glued up the key again with some super glue....

Here is a pic of the key being glued...

http://img244.imageshack.us/img244/7176/img0291ki0.jpg

While definitely not a hard or complicated "DIY" project I did save myself about $200 and had fun while doing it...

Dev 03-08-2007 06:07 PM

Great job!

jason 77 03-09-2007 03:13 PM

Quote:

Originally Posted by Dev (Post 5649130)
Great job!


Thanks :)

trizzuth 05-19-2007 08:11 AM

dude, that's fresh, you're the freakin man and will probably save more than a few people hundreds of dollars!

antzcrashing 05-19-2007 08:37 AM

:clap: :clap: :clap: :clap:

:thumbup: :thumbup: :thumbsup:

04e46conv 06-27-2007 09:05 AM

Nice!

On that site I found same size batt, same voltage but a little more mAH....

http://www.mouser.com/search/Refine....RefType=Header

Hum...... Maybe a little more performance???

I think it would need more voltage rather then mAH... I am going to see if I can find the same size in 3.5 volts or 4.0.....

tsylatac 06-27-2007 09:18 AM

More mAH means the battery has more capacity and will last longer (esp between charges).

As for voltage, in this case, it's possible that increased voltage will provide extended range but it's also possible that you'll damage the electronics of the key, depending on how sensitive they are. There's usually some protection for things like this but the key is made from a closed-case and not meant to be servicable so who knows. 3V ain't much and it *most likely* wouldn't hurt to increase it a bit but I would stick to the stock battery to avoid killing your key....

Quote:

Originally Posted by 04e46conv (Post 6225102)
Nice!

On that site I found same size batt, same voltage but a little more mAH....

http://www.mouser.com/search/Refine....RefType=Header

Hum...... Maybe a little more performance???

I think it would need more voltage rather then mAH... I am going to see if I can find the same size in 3.5 volts or 4.0.....


04e46conv 06-27-2007 09:26 AM

Yeah I am thinking the poor range might be from the battery charge drooping quickly (due to low mAH) so a little higher on that would help fix that.....

Then a little more voltage would help with range...

I would assume there is some safety factor engineered into the design so .5 volts more should hurt it too much,

and when you unlock the door your taping the button its not like your holing it with another 3 volts going through the circuit for 5 min...

The key I use the most is getting work out and crappy looking so I might give it a shot on that one...

tsylatac 06-27-2007 09:41 AM

Let us know how it goes! :thumbsup:

04e46conv 06-27-2007 09:43 AM

Yeah no prob I will start a new thread with a DIY if it works and doesn't blow up....HeHe

TKC 06-27-2007 11:43 AM

This is GREAT!!! I am SO GLAD I told the dealer no way on $200+ for a new key!!

About to order the battery, but there's 2.... which one do I need?

http://www.mouser.com/search/refine....onic+VL2020+3v


(The difference is 2 Pin Vert or 2 Pin Horiz)

Thanks!

TKC 07-06-2007 11:45 AM

Ok, I tried this last night, but it still doesn't work. Question:

How are those metal prongs attached to the battery and what did you use to re-attach the ones from the old battery to the new battery?

http://img252.imageshack.us/img252/6563/img0285be9.jpg

jason 77 07-06-2007 12:17 PM

Quote:

Originally Posted by TKC (Post 6265759)
Ok, I tried this last night, but it still doesn't work. Question:

How are those metal prongs attached to the battery and what did you use to re-attach the ones from the old battery to the new battery?

http://img252.imageshack.us/img252/6563/img0285be9.jpg

The metal tabs are spot welded on, and I just soldered the new tabs to the old ones. I did have to putz with bending the tabs to get them to line up with the ones on the battery.... Make sure you get the positive + on the battery going to the positive + on the circuit board!!!

TKC 07-06-2007 12:25 PM

Great! Thanks for the info! I'll try again.

The other problem I see is that I only have the one key (used car) so I don't have a spare to use in the re-programming you mentioned above. I guess I'll figure that part out when I get there.

TheRiddle 08-14-2007 01:07 PM

Already opened the key (made a little mess but i'll solve it later)..

anyway..

for pure personal sake i've tried with a tester to check if the battery is really drained

..full charge..

in fact the remote works 1 time on 100 try..

anyone knows if it might be related to the reciever into the mirror?

zikhkd 08-14-2007 01:53 PM

my battery is dead also.. but I only have one key, I don't think I would be able to reprogram it with one key.. :(

BBB543 08-14-2007 10:25 PM

i thought the key recharged the battery every time you turned the key? I think i read that in the manual

TKC 08-15-2007 11:47 AM

Quote:

Originally Posted by BBB543 (Post 6469200)
i thought the key recharged the battery every time you turned the key? I think i read that in the manual

It does, but even rechargable batteries die eventually.

zikhkd 08-15-2007 06:52 PM

does anyone know of a way to change the battery and reset the key without having to use another key?

TKC 08-15-2007 07:13 PM

Quote:

Originally Posted by sikhkd (Post 6473460)
does anyone know of a way to change the battery and reset the key without having to use another key?

If so, let me know cause I changed my battery and it still doesn't work cause I don't have a second key either.

I was wondering if the dealer could do it.

Otherwise, I guess I'm just takin it and paying $250 for the new key. :(


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