Key fob battery

[Beargap]

This is a minor issue, I know, but I started getting a "Replace Key Fob battery" message on the dash of our 2021 Explorer XLT. The Fob on my 2008 Mustang with over 175K miles has never been replaced, is it typical that these new fobs go out this soon?

 

[Dale5403]

This is a minor issue, I know, but I started getting a "Replace Key Fob battery" message on the dash of our 2021 Explorer XLT. The Fob on my 2008 Mustang with over 175K miles has never been replaced, is it typical that these new fobs go out this soon?

Pretty normal for me. These newer vehicles have a lot going on with the key fob.

 

[J_C]

Depends on how often you use it? Is it push start ignition so the fob is constantly (intermittently pulsed) sending out a signal? That could also account for it.

Maybe just a bad battery, old stock or inferior supplier due to covid supply chain issues? If it uses CR2032, I have several things that use that size and usually just get a ~10 pack of a major brand off an ebay seller, one that lists the manufacture or expiration date. MUCH cheaper per cell than buying at a local brick and mortar seller.

 

[Beargap]

Depends on how often you use it? Is it push start ignition so the fob is constantly (intermittently pulsed) sending out a signal? That could also account for it.

Maybe just a bad battery, old stock or inferior supplier due to covid supply chain issues? If it uses CR2032, I have several things that use that size and usually just get a ~10 pack of a major brand off an ebay seller, one that lists the manufacture or expiration date. MUCH cheaper per cell than buying at a local brick and mortar seller.

The battery is a 2450 3v lithium, and I have a couple coming by mail. We never use any of the buttons on the fob...just have it on us so we can unlock the doors and start the car, so the early failure, particularly with a lithium cell, seemed odd. I use the unlock or trunk buttons on my 16 year old car all the time and have never changed that battery.

BTW, I removed the battery to get the type as that doesn't seem to be in the manual. It measured 2.9v, which is not really "low" to me. I didn't check the second fob, though.

 

[J_C]

Yes if it is only down to 2.9V, the fob isn't using most of the battery capacity, making me wonder if it's poorly designed or just has bad contacts in it.

 

[Beargap]

I decided I better check my wife's fob, since both were in the car when the low battery signal came on. With only my fob...no low battery alarm, but with only hers it did come on. I tested her battery and it was even better than mine, a full 3v. I didn't see any contact corrosion, but wiped them down and reinstalled the battery. Now no low battery signal. Hmmm...

I had a similar problem with the left rear tail light a year or so ago. It would not come on, although turn and reverse were OK. Of course, that is the built-in LED and the whole tail light has to be replaced, so I did that and it would not work, either! The dealer confirmed voltage was present on the plug, which is why he wanted to change the tail light, but what I finally discovered was the socket on the lamp had a "dirty" connection. Cleaning the female socket with a paper clip restored operation of the original lamp and I was able to return the replacement for a refund. I've not had a problem since.

 

[peterk9]

I decided I better check my wife's fob, since both were in the car when the low battery signal came on. With only my fob...no low battery alarm, but with only hers it did come on. I tested her battery and it was even better than mine, a full 3v. I didn't see any contact corrosion, but wiped them down and reinstalled the battery. Now no low battery signal. Hmmm...

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As per the manual;

Note: Do not wipe off any grease on the battery terminals or on the back surface of the circuit board.

Peter

 

[J_C]

^ If it stops working again and corrosion is noted, then I'd be concerned but otherwise, if it works, it works. Aren't the contacts nickel plated and the PCB, either tinned or gold or conductive carbon coated? There are plenty of remotes I have with 2032/etc coin cells that don't need grease to work well.

I'm even wondering if the primary concern of the author of that note in the manual, was that people will smear around the grease where it shouldn't be, and do end up fouling the PCB contact since that side is a large surface area and not the same tension per surface area as the edges of the cell.

 

[Beargap]

As per the manual;

Note: Do not wipe off any grease on the battery terminals or on the back surface of the circuit board.

Peter

I missed that as it is in the section covering a different fob than we have, but it is certainly a curious statement. I wonder if the intent is to prevent greasy fingers leaving grease on these parts? That would make more sense.

In any event, there was no grease in my fob, just dirt from riding around in pockets.

=Vic=