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Replaced my key fob battery

StarLog

Supporting Member
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Mar 11, 2019
458
208
MCO
So, I know the key fob is good, and it was getting weak. So I put a new battery in the fob.
Now it does not open the doors.
I made a mobile appointment, and now Tesla wants to charge me $87.50 to come and program the fob. WTF.

Last time, about 4 months ago, I provided a new battery to the mobile tech and he did it for free, at my work.

This attitude will make me not want another Tesla, and go for the other more service oriented EV dealers.
 
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whitex

Well-Known Member
Sep 30, 2015
6,728
8,564
Seattle area, WA
I've changed batteries in my fobs without any issues. Heck, when I did one of the annual services Tesla changed a battery in a fob and left another battery in the cupholder for the second fob, so obviously intended for self service. Did the very early cars have fobs which need reprogramming when changing batteries, or did something go wrong with the battery change? Was there a dead battery in the fob for a long time prior to the change?
 
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StarLog

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Mar 11, 2019
458
208
MCO
No dead battery, was a bit weak. I will go buy a new battery again, and see what happens.
Thanks

P.S. Tesla called me, and said they will give me a battery if it is bad.
So I am going to stop by the SC.
 
Last edited:

rjscoder

Member
Aug 22, 2018
382
213
Ohio
No dead battery, was a bit weak. I will go buy a new battery again, and see what happens.
Thanks

P.S. Tesla called me, and said they will give me a battery if it is bad.
So I am going to stop by the SC.

Dude that battery is $0.50 on eBay. Are you really going to drive all the way to SC for a 50 cent item?
 
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StarLog

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Mar 11, 2019
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Dude that battery is $0.50 on eBay. Are you really going to drive all the way to SC for a 50 cent item?

I literally drive right by the SC on the way home. but first I will buy one, as I stated above. thanks for the love.
 
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D.E.

Uncorked
Oct 12, 2016
767
1,016
Ann Arbor, MI
I changed batteries in both my fobs without any problems at all. I doubt you lose programming when simply changing a battery or a lot of us would have run into the problem. It’s possible you put a dead battery in there. That’s unlikely, though, but you do have something is going on so it’s the first thing I’d rule out.

There’s a device called a multimeter that’s well worth having. They can be as cheap as $5 up to over $100. Checking batteries is one thing they do well but a multimeter is something useful for many things. For the very cheap, try Harbor Freight Tools. Otherwise Amazon has them. I like the auto-off feature because II tend to leave them on. Besides checking batteries, you can use a multimeter to check circuits, check to see if a wire makes a connection (as in a wire that produces a short circuit), or whether a wire is broken, you can check to see if power is supplied to a wire with the car off, for installing something (like a dash cam). You can check fuses with them, old filament style light bulbs. There are some multimeters built with a check batteries feature, they put a small load on the battery then indicate whether the voltage is maintained with the load as with a good battery, or whether the voltage drops with a load, as with a battery that is near dead but still has some voltage.

For the fob, a new battery is worth trying. If you have one working fob, that should keep you going until you find yourself near a service center. Get a name brand battery, occasionally some of the really cheap batteries can leak. That can put a nonconductive surface on the battery contacts. So while you have the fob open make sure the battery contacts are clean and shiny.

I believe they have new fobs, ones that avoid the theft risk of code copying by thieves. I don’t know if the 2013 models are compatible with the new fobs but if you’re going to spend $87, it might be worth looking into the new one, can’t say. I’m not in a high thievery area. Still it’s all or nothing, you only need one thief.

As I recall there’s a place you can put a fob to start the car even with a dead fob battery, I think it is near my console somewhere, but that might tell you if your fob still works for the car. I’m guessing here but it should be easy to try.

So my suggestions:
Try another new fob battery
Try fob in “dead fob battery” area of car to see if fob works there
Enable smart phone use for opening, locking, and driving car if you have a smart phone capable.
Get an inexpensive multimeter if you are a do it yourself sort of a person

Please let us know what the problem was once you sort it out.
 

StarLog

Supporting Member
Supporting Member
Mar 11, 2019
458
208
MCO
@D.E.

Your too funny, I am an engineer, so thanks for the multimeter suggestion.
I will get a replacement battery today at the local batteriesPlus store.
Stay Tuned........
 
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murphyS90D

Member
Jul 2, 2016
695
500
Horsham, PA
You have to measure battery voltage while the battery is under load to get an accurate reading. The voltage will come up if there is no load. Typically as a battery ages the internal resistance of the battery will increase. That resistance is in series with the circuit so the available voltage goes down. This is in addition to the voltage dropping because the battery is being discharged.

EE 1962
 

Fossil Fool

Member
Aug 13, 2019
135
199
Prescott, AZ
So, I know the key fob is good, and it was getting weak. So I put a new battery in the fob.
Now it does not open the doors.
I made a mobile appointment, and now Tesla wants to charge me $87.50 to come and program the fob. WTF.

Last time, about 4 months ago, I provided a new battery to the mobile tech and he did it for free, at my work.

This attitude will make me not want another Tesla, and go for the other more service oriented EV dealers.



Goodbye!
 

maximizese

Member
Jan 16, 2018
488
478
California
I recently replaced one of our key fob battery with some new-old-stock batteries I had lying around the house (stocked up). I bought a 10 pack of Panasonic batteries for like $5 on Amazon. Great price, but you get what you paid for...some of the batteries seem to be duds. Perhaps your fob is fine, but your replacement battery was no good.
 
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JPoldo

Member
Aug 13, 2017
361
238
Bonita,FL & Boston,MA
I recommend purchasing a name brand battery to avoid problems. Last week my 2 yr old fob needed a battery replacement. Amazon Prime offers an Energizer 2-pack with one-day free delivery for under $4. Later, I discovered price is double at HD, Lowes, and drug stores. Once one fob battery fails, surely the other fob will fail soon so a two pack makes good sense. Be sure to peel off the adhesive sticker on one side of battery before installation. Watch a Youtube video if unsure about steps for replacement.
 

StarLog

Supporting Member
Supporting Member
Mar 11, 2019
458
208
MCO
Went to BAtteries plus, and they tested the battery, it was 3.0v
Installed and nothing, either the fob went bad, or it really needs to be reprogrammed.
 

boaterva

Supporting Member
Supporting Member
Apr 2, 2016
7,575
3,815
Northern Virginia, USA
Several threads on this, and I changed fob batteries twice. One killed the fob, had to be reset by the service center, one worked fine. I did the one that worked in the car, which may be the reason it worked, or may be a coincidence. Always wondered if these were part of the old annual service for a reason.

SC said they had to reset the 'gateway' which seems nuts for a fob failure, but who knows. Does make some sense that keeping the car awake and connected (within range of the fob) when you change the battery is a good idea.

S and X have places that it works without a battery, see the manual.
 
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docl

Member
May 11, 2019
15
20
Denmark
Most likely you damaged the keyfob when changing the battery.
If there is a small dent in the metal under the battery (where the circle is in the photo), then the battery shorts and the fob stops working. Might be a very subtle damage to the metal.
Place a piece of scotch tape over that place and replace with a new battery (again).
 

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StarLog

Supporting Member
Supporting Member
Mar 11, 2019
458
208
MCO
Most likely you damaged the keyfob when changing the battery.
If there is a small dent in the metal under the battery (where the circle is in the photo), then the battery shorts and the fob stops working. Might be a very subtle damage to the metal.
Place a piece of scotch tape over that place and replace with a new battery (again).

Thank you very much, I looked and indeed, it was bent, and so I pushed it down with a small screw driver. Then put electrical tape on it, and now it works.

Your a most excellent tech.
 
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seclinton

Member
May 25, 2015
393
278
Newark, CA
You have to measure battery voltage while the battery is under load to get an accurate reading. The voltage will come up if there is no load. Typically as a battery ages the internal resistance of the battery will increase. That resistance is in series with the circuit so the available voltage goes down. This is in addition to the voltage dropping because the battery is being discharged.

EE 1962

there’s right in this statement and nice post.

a multimeter on a cell will show you the rest voltage. Depending on the stare of charge you might see anywhere from 3.2-3.7V on the coin. This will give you basic health I.e 100% 50% 25% or DOA. Checking the impedance DC will help your confirm if the battery is indeed consumed. Not sure of starting impedance but let’s assume 18-25mohm. A jump to 75 or 100mohm would indicated a discharged battery or in a rechargeable fading cycle life. Ohh batteries are fun
 
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wycolo

Active Member
May 16, 2012
3,099
468
WA & WY
Fresh coins measure 3.3v or higher. I've purchased some at 3.0v, but that's ok since they last so long anyway. Check the package for mfr date might help.

Yesterday I *had* to move car but fob was not recognized (and I did not know specific spot to place battery-less fob). Plus I could not find my 6 pack of fresh coins. I did find amongst my battery refuse a 2.7v (resting voltage) coin that luckily got the car safely into the garage. :)

Where does one place fob, with battery removed, to operate car?
--
 
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