Key Fob Battery CR2032 How Long Did You Battery Last?

HOW LONG DID YOUR KEY FOB BATTERY LAST?
WHY DID YOU REPLACE IT? WAS IT GETTING FLAKY?
WHAT VOLTAGE WAS YOUR OLD BATTERY WHEN YOU REPLACED IT?

The CR2032 is pretty cheap I know. I just ordered some more, but just
curious how long your battery last and how to test. Here is my opinion.
I never really tracked it, forget when I change battery, but I'd estimate
two years using every day? I am going to replace them based on calendar
spec... say 24 months. When they start to go, operation gets inconsistent.

Just like a "12 volt" car battery is 12.6 volts open voltage (no load), these
little lithium ion batteries also have higher volts than their "3.0 volt" label.

New Battery
I got a pack of NEW CR's and they measured 3.37V. They hold 3.17Vwith
a 100 ohm load. After load test they recovered to 3.26V.

Used Battery
My used batteries measure 3.10 volts (no load with a volt meter). They
suck down to 2.8 volt or less with 100 ohm load. They still worked, but
range is degraded and on occasion nothing happens, even close.

Estimate of Life
I suspect depending on how much you use it, 2-4 years is reasonable.
It may work after 4 years, of everyday use, but put a new battery in.
You will see a difference. Installing a new battery the range and operation
are noticeably better.

100ohm Test
My 100ohm load test is severe, because the norma load is not constant,
there is a pulse coming out of the transmitter, not constant carrier. I came
upwith 100 ohm based on FCC rules, max transmitter power is limited to
100mW or 250 meter (820 feet) range (I recall), which ever one is limiting.
Since the antenna in the key fob is pretty small we are power limited and
range is will under 820 feet. Power may be well under 100mW as well
just because the fob is made to work at close range. However using 100mW
that is abut 0.03 amps (30mV) at 3 volts. That is way more than an electronic
or clock memory. In my opinion if it sucks down below 2.9V or 2.8V it is
tired and spent for FOB use. It will still work as memory stay alive or small
calculator..

Conclusion
If it reads less than 3.2 volts, it is not 100%. When you get a
new one as I say they are 3.26-3.36 volts. Once they get down to 3.1 volts
they are pretty low and your FOB range is less. I suggest changing sooner
than later. The gents below bragging how long they are milking their battery
may be fine, but I am sure their range is limited.

DEALS
I bought 5 Sony for $2.00, $0.40/each and 5 Generic for $0.75, or $0.15/each.

Sony, Eveready, Panasonic or Duracell are better I assume then generic, but
eBay you don't know what you are getting. It could be bootleg. Buying locally
they are more expensive. Also the same factory may make name brands, and
at night make generics and just change the markings and packaging.

INCREASE RANGE
FYI it has been shown if you hold the FOB up to your jaw or temple, skull,
it acts as an antenna and your key FOB range is extended.... not sure what
that does to your brain.. ha ha.
https://www.youtube.com/watch?v=0Uqf71muwWc
https://www.youtube.com/watch?v=_jACSPipPSE


NOTE
Warning if you unlock it too far from the car and keep pushing the FOB you
can de-couple it from the car... (according to owner manual). Also unlocking
times out and it will re-lock if you take too long to get to car and open door.

Thanks, good information for those wanting to check their new batteries or just confirming they need to replace the battery in their key. What I'm more curious about, and what led me to look at your thread, was how long a new CR2032 lasted for you?

I've been mostly not using my key to lock/unlock, as I find the "keyless remote" feature on my vehicle more useful, so I suspect I'd be a bad data point.

If you keep an eye on "woot.com" , the Amazon subsidiary that sells items at a discount that are in surplus, batteries come up in name brands at a regular basis ....
Button cells, like the ones used in keyfobs are sold in packs of 6 or 10 for about a buck each....sealed, good for 10+ years....

Key Fob Battery Life

3 years, 5 months (53K miles) and counting....

I bought my car in January 2004. I've changed the battery once on the fob that I use, and the spare one still has the original battery, and it still works.

Local retailer sells them for 50 cents. I have ten spares. I'm good for 100 years.

pushgears said:

3 years, 5 months (53K miles) and counting....

Click to expand...

Mike_04GolfTDI said:

I bought my car in January 2004. I've changed the battery once on the fob that I use, and the spare one still has the original battery, and it still works.

Local retailer sells them for 50 cents. I have ten spares. I'm good for 100 years.

Click to expand...

Get a new one and enjoy better range. Even a weak car battery will start your car. One day it will let you down. You are saving $0.50. Congrats. Cheers

I've changed mine twice in 5 1/2 years. About due for another change as my range is degraded. Also, my MFD indicates when the key battery is low. I was surprised to see that 3 years ago, and I changed the battery at that time.

bobt2382 said:

I've changed mine twice in 5 1/2 years. About due for another change as my range is degraded. Also, my MFD indicates when the key battery is low. I was surprised to see that 3 years ago, and I changed the battery at that time.

Click to expand...

As Ed McMahon said to Johnny Carson when Carson said some unusual fact or trivia, Ed would say, "I did not know that Sir... "

Ten years plus. Never used the spare, never replaced the battery on the FOB I use.

Mine finally died a couple of months ago. So it lasted 17 years! It started getting a bit flaky a couple of months before quitting altogether, the symptoms were that it wouldn't unlock the trunk (maybe that code takes slightly more power to send?) or wouldn't re-open the door immediately after locking it.

It would no longer function at this voltage:

and the batteries were clearly at the end of their life anyway:


The corroded one measured 2.865V, the other was slightly better at 2.937V.
My wife's key fob (which gets used less) still works fine on its original batteries.

Keep in ine that you are reading with no load. Likely those old batteries will drop voltage like a stone when loaded . . .