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      07-23-2021, 06:08 PM   #1
mariocaz
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Key Battery for E85 ?

Hi,

I have 2 keys of my E85, but one I never used it, not the last owner either.

I bought a brush tooth charger and charge it one day complete, I felt it very little warm when I took it from the charge but the key is not working at all.

So my question is do I need to replace the battery if the key wasn´t used for years ? (never charged it either), if yes, what type of battery I need to buy ?

Or almost sure I need to program it again ?

Thank you so much!!
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      07-23-2021, 11:24 PM   #2
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      07-25-2021, 06:21 PM   #3
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You can buy blank keys off ali express and get someone local to cut & program it or buy an ak90+ and DIY. Lots of guides off the internet. I made 2 keys that'll unlock the door but wont start the car and leave those at home.

The flip keys off ali express has removable button battery. Good to have spares..
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      07-26-2021, 08:47 PM   #4
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Driving the car supposedly charges the key. Drive it with the dead key to see if it charges. Drive it for a while if possible.
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      07-28-2021, 06:23 PM   #5
mariocaz
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I charged the key with a tooth brush charger and it works to start the car but it is not opening and closing the doors, I see some videos at Utube to program it pressing and holding the unlock button and 3 times the center button but no luck at all.

Any advise ?

Thank you guys!!
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      07-28-2021, 07:50 PM   #6
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The key will start the car even without a charge, as the key allows the switch to turn, unlike the new cars with FOBs. The battery in the key is to send the signal to the car, to unlock the doors or the trunk.. I don't think your key is charged.
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      07-28-2021, 08:38 PM   #7
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oh ok, so you recommend me to change the battery ?
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      07-29-2021, 08:19 AM   #8
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In the car ignition switch, yes. Drive the car for a while to charge it up. What do you have to lose?
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      07-29-2021, 02:56 PM   #9
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Quote:
Originally Posted by couchflyer View Post
The key will start the car even without a charge, as the key allows the switch to turn, unlike the new cars with FOBs. The battery in the key is to send the signal to the car, to unlock the doors or the trunk.. I don't think your key is charged.
Are you sure about that? I thought the key had a transponder for security so that only a key with an active one will start the car (thus if the battery dies, the key won't work). I don't know this to be a fact, but it seems unlikely it is only the cut key needed to start the car. I know the GM cars with the transponder keys would turn the starter over if the key was cut to the car, but it wouldn't actually start and run without the transponder in the cut key.
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      07-29-2021, 11:20 PM   #10
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My key didn't open the locks by pressing the buttons. I read the manual which said the car charges the key when driving. I used that same key, it started the car, drove around, and now the doors unlock as well as opening the top. That is why I am saying what I said.
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      07-30-2021, 09:37 AM   #11
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Quote:
Originally Posted by couchflyer View Post
My key didn't open the locks by pressing the buttons. I read the manual which said the car charges the key when driving. I used that same key, it started the car, drove around, and now the doors unlock as well as opening the top. That is why I am saying what I said.
Got it. Great info. I am always concerned my keys will be lifeless one day as I don't drive mine often. I swap keys once in a while to allow for charging. I need to get a charger to use in the house.
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      07-30-2021, 01:31 PM   #12
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I found this on another forum. The highlighting was done by whoever posted it:
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      07-31-2021, 08:23 PM   #13
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The toothbrush charger works. I have a 2001 E39 that the spare key (looks the same as the Z4) wouldn't remotely lock/unlock the vehicle. After 24 hours on the toothbrush charger, it started working again. Batteries do completely die, so in that case, a new battery will be required. Replacement is not trivial, requires some cutting/soldering/gluing, but not too bad, cost about $8 for a new batt.
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      08-02-2021, 08:53 AM   #14
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I have been thinking the "toothbrush charger" was the boxy one I was seeing in videos with programing the new keys. Had no idea we were talking about an induction charger. I have Sonicare toothbrushes and gave it a try last night with my keys. Worked like a charm. Wish I had known about this before. I could have been charging them all along.
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