Carry a spare key-fob battery in your glove box.
- Thread starter JimPghPA
- Start date
I changed the batts in my mazda remotes as a preventative. I hate the keyless start and i don't want to deal with it when it messes up, i.e. dead remotes, so i will just change batteries every 2 years.
So I guess it is vehicle dependent?
My Santa Fe says to just push the Start button with the fob itself and it will start, even with no battery in it. Seems it is one of the NFC powered chips in the fob, so that is good to know.
Also, it will not lock with a key in the vehicle. I found this out when we were traveling once, we got out at a rest stop and wife put her purse (with other key) in the back hatch area without me know it.
It would not lock and I could not figure out why till I found out the other key was in the vehicle.
I don't know how it knows the difference between me outside the door with a key and a key in the back of the vehicle (and my key outside) and does not let me lock it?
My Santa Fe says to just push the Start button with the fob itself and it will start, even with no battery in it. Seems it is one of the NFC powered chips in the fob, so that is good to know.
Also, it will not lock with a key in the vehicle. I found this out when we were traveling once, we got out at a rest stop and wife put her purse (with other key) in the back hatch area without me know it.
It would not lock and I could not figure out why till I found out the other key was in the vehicle.
I don't know how it knows the difference between me outside the door with a key and a key in the back of the vehicle (and my key outside) and does not let me lock it?
As others mentioned above-at least on my wife's Jeep the hold next to the button trick works even with the battery removed.
We tested that when she first got a "low battery" message in the car. I had CR2032s on hand(they're used in a bunch of stuff aside from key fobs) and changed it right away, but just for the sake of experimenting-as I said-we pulled it completely and she made sure she knew how to start with it dead just in case.
We tested that when she first got a "low battery" message in the car. I had CR2032s on hand(they're used in a bunch of stuff aside from key fobs) and changed it right away, but just for the sake of experimenting-as I said-we pulled it completely and she made sure she knew how to start with it dead just in case.
When I had a BMW, it would show a low battery warning for the key fob. Easy to replace since it used a 2032 battery.
I keep a small stock of 2032 batteries around since every key fob I have, and my family has, uses that size.
But I keep a couple 2025 and still have a couple 2016 batteries from a fob that used 2 of them stacked together (99 Dodge Ram). The 2025 went into a Cadillac key fob for my old 95 Cadillac Fleetwood Brougham that I sold to a guy in Los Angeles a few years back.
I replace them each year or so… I keep a big enough stash that I can swap them out regularly.
I keep a small stock of 2032 batteries around since every key fob I have, and my family has, uses that size.
But I keep a couple 2025 and still have a couple 2016 batteries from a fob that used 2 of them stacked together (99 Dodge Ram). The 2025 went into a Cadillac key fob for my old 95 Cadillac Fleetwood Brougham that I sold to a guy in Los Angeles a few years back.
I replace them each year or so… I keep a big enough stash that I can swap them out regularly.
The RFID chip on the key or remote (what some call a key fob) gets energized when close enough to the ignition lock or remote insertion slot. The battery is needed only for other function like remote locks and panic function. Some vehicles, like my Miss Moneypenny, come with remotes/electronic keys that recharge once inserted into the slot.
All the same, the OP’s suggestion is not a bad one, especially if out of town travel is on the agenda. Unused batteries have a very long shelf life and why not have a spare in the car to save the hassle of a separate trip to find a replacement?
I only carry the extra fob when we go out of town. I always change my batteries once a year. Sometimes sooner if my battery stock is getting close to 2 years of expiration date. I even change that forgotten battery that is in PC's LOL
My '21 Toyota venza flashed a dashboard warning that FOB battery was low after 5 months. I had two spares in glove box. I expected to get more than 5 months.
I turned the spare Fob off to hopefully preserve the battery by holding the lock button and pressing unlock button twice.
I turned the spare Fob off to hopefully preserve the battery by holding the lock button and pressing unlock button twice.
I'm wondering why many haven't gone to rechargeable batteries. It could even be something like a rechargeable coin cell so that it can be replaced cheaply. Put in a USB-C charging port on the outside.
Not familiar with any rechargeable coin cells. USB-C charging port would also be bad. Keys get dropped in water all the time. Sealed outer case means not really an issue for the occasional light coat of water. USB-C port would allow water in.
Mine go bad all the time after 4-6 months. I usually get a set of 10-20 on eBay. Probably worse having it in the car because the proximity to the car means it's probably always talking to the car burning out the battery faster.
gathermewool
Site Donor 2023
I just use a DMM to determine when the batteries need to be replaced. I check when the warning on my car starts to ding at us and the display says to check the battery.
During my last replacement, when I started getting warnings, the batteries were:
Old: 2.924VDC.
New: 3.280VDC.
During my last replacement, when I started getting warnings, the batteries were:
Old: 2.924VDC.
New: 3.280VDC.
I disabled all that nonsense on my 04; I use the key embedded in the fob to open the door and the fob is inserted into the dash; i realize newer systems are probably better
Wow, my '18 Santa Fe is still on original batteries in both remotes.
I had a 2013 Ford Fusion that I finally traded in in 2019 that was on the original batteries in the remotes. And it was my daily driver.
So is my '18 Transit 250 work van, although I switch which one of the 2 fob keys I have regularly (one in the pocket, one on the key ring). Helps that Ford only uses the battery for power locks & panic mode, the RFC chip handles the starting.
Have to renew plates on car every two years. I just replace all key fob batteries at the same time and never have to worry about it. Preventative maintenance.
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It happened to me this year. My Jaguar's Key Fob battery went dead & the system never recognized & wasn't able to start the car. Out of desperation, I took off the battery of my Ford Escape Key Fob & switched both batteries...walla, I got the Jag started. Wow, it was scary as there are no retail stores nearby to buy a coin battery. Luckily both Escape's & Jags Key Fobs take the same coin battery (CR2032). Never buy a Chinese made coin battery even though it is from a reputable brand. Japan, USA & Switzerland made batteries are the best.
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