Key Fob Battery Replacement = Dead Key

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scottbrooks

New member
Joined
Apr 24, 2021
Messages
3
Hi,

I have a 2016 SV that has mostly been reliable. I just replaced the battery in the fob and now it is dead. I tried a couple of the reset sequences published on dealer sites but (a) they are for cars with a key socket and (b) it didn't work. The dealer wants $80 + tax to reset the key.

Any ideas on how to reprogram this at home?


Unrelated: I can't get the car to register more than 90 miles range with a full charge. Common?
 
There is no need to "reset" anything when just replacing the fob battery. If the fob was working before replacing the battery, then you have a defective battery, battery installed wrong, or you damaged the circuit board in the fob by putting the wrong battery in it. Try removing the battery from the fob and then holding the fob directly against the start button of the car, If the car starts, then replacing the fob battery with a good one of the correct size may fix it.
 
Thanks. This is a weird one...

1) I tested the new battery with my multimeter. It is good.
2) The fob is recognized by the car and works in the dead battery proximity start process
3) It was in the correct way, + side down
4) It is the correct 2025 battery

I swapped in the old battery, also a 2025 and it works. I don't have a caliper but I visually inspected the two batteries. It looks like the new one is maybe a hair thinner so I gently bent the tabs up. Not so much! I popped the old battery in and it works fine, but the level is low.

Any ideas?
 
GerryAZ said:
Try another new 2025 battery. Digital multimeters have very high input impedance so a defective battery can test OK (show normal voltage for a new battery), but not be able to deliver current.

Yes, and there are so many Chinese counterfeit batteries being sold that it's harder to find a real one than you would think.
 
GerryAZ said:
Try another new 2025 battery. Digital multimeters have very high input impedance so a defective battery can test OK (show normal voltage for a new battery), but not be able to deliver current.
^^^ THIS
I just replaced my key fob battery with what was (supposed to be) a new battery...and no joy.
BTW, you can fit a 2032 in our key fobs if you have any laying around...and it will work.
 
GerryAZ said:
Try another new 2025 battery. Digital multimeters have very high input impedance so a defective battery can test OK (show normal voltage for a new battery), but not be able to deliver current.

An alternate battery test for small "coin" type batteries, e.g. 2025 when using a multimeter, is to use the ammeter scale (highest setting 1st)
to do a basic load test. A good 2025 should provide about 100-200 milliamps.
 
lorenfb said:
GerryAZ said:
Try another new 2025 battery. Digital multimeters have very high input impedance so a defective battery can test OK (show normal voltage for a new battery), but not be able to deliver current.

An alternate battery test for small "coin" type batteries, e.g. 2025 when using a multimeter, is to use the ammeter scale (highest setting 1st)
to do a basic load test. A good 2025 should provide about 100-200 milliamps.
Not sure I understand why you are saying, do you mean to short circuit the battery with an ammeter and shorted out it should show 100-200ma? if so I guess I've never done that, I for sure wouldn't want to do it with a higher current battery but may be ok with something as tiny as a coin battery?
Again if I understand you correctly, what should a 2032 battery be capable for ma? I'd assume more than a 2025 as it's larger.
 
jjeff said:
lorenfb said:
An alternate battery test for small "coin" type batteries, e.g. 2025 when using a multimeter, is to use the ammeter scale (highest setting 1st)
to do a basic load test. A good 2025 should provide about 100-200 milliamps.
Not sure I understand why you are saying, do you mean to short circuit the battery with an ammeter and shorted out it should show 100-200ma?

Correct.
jjeff said:
if so I guess I've never done that, I for sure wouldn't want to do it with a higher current battery but may be ok with something as tiny as a coin battery?

These smaller batteries have short circuit current capabilities, when new, of << 1.0A.

jjeff said:
Again if I understand you correctly, what should a 2032 battery be capable for ma? I'd assume more than a 2025 as it's larger.

So given the volume of these coin type batteries, one could determine the ratio of the short current, i.e. for the same type of electrolyte.
I had a 2032 battery which is probably 2-3 years old, and it only provided about 70ma. I didn't have one as new as my 2025 I tested.

I was having a similar key fob problem with my 2013 Leaf, where I replaced the 2025 battery from my older stock. The fob had the
same problem until I bought some new ones. When comparing my old stock 2025 to my new 2025s from Amazon, the old stock
only provided about 20-30% on the new 2025s, although the voltage was about the same.
 
LeftieBiker said:
You wouldn't be shorting the battery - you'd be placing a substantial load on it from the resistor in the ammeter.

Correct! Obviously one would never use that approach when testing a 18650 Li Ion with a typical VOM.
 
lorenfb said:
LeftieBiker said:
You wouldn't be shorting the battery - you'd be placing a substantial load on it from the resistor in the ammeter.

Correct! Obviously one would never use that approach when testing a 18650 Li Ion with a typical VOM.

VOM ===> VOOM!
 
LeftieBiker said:
scottbrooks said:
I popped a 2032 in and it works great

Some people have no trouble with using a 2032, while others find it too thick.

It can be quite tricky to get the cover back on when using a 2032, I've found putting on one side of the remote first works best and then the other......unfortunately I always forget what side so it's a 50/50 chance. If I can't get the second side to click in place I take it apart and put that side first and doing that I've always managed to get it back together even using the thicker 2032.
Do the newer gen Leafs still come with the poor value 2025 batteries or have they finally redesigned the remote to accept the same price but 50% more capacity 2032?
 
jjeff said:
Do the newer gen Leafs still come with the poor value 2025 batteries or have they finally redesigned the remote to accept the same price but 50% more capacity 2032?

The original 2025 battery for my '13 Leaf lasted seven years. Why risk damaging the remote, e.g. the internal circuit board/components, by having to force the lid on with an oversize battery?
 
I found the 2025 replacement to be a snug fit in the remote for my 2019 so would not want to try to force a 2032 into it (same with previous cars), but I add a thin piece of stiff plastic under the panic button to eliminate inadvertent operation of the horn and lights. All 3 of my LEAF's used the same size 2025 battery and they last between 1 and 2 years for the daily use remote (much longer for the spare that stays outside communication range of the car).
 
lorenfb said:
jjeff said:
Do the newer gen Leafs still come with the poor value 2025 batteries or have they finally redesigned the remote to accept the same price but 50% more capacity 2032?

The original 2025 battery for my '13 Leaf lasted seven years. Why risk damaging the remote, e.g. the internal circuit board/components, by having to force the lid on with an oversize battery?
Like others I found my 2025 battery lasting 1-2yrs, my 2032's tend to last 3-4yrs and personally, I feel prying the remote apart is the hardest part on the remote so if I can cut that by 50% or more I figure I'm better off.
Note I don't use a pliers or vice to get the remote back together, just a slow steady pressure with my fingers, if it doesn't click together I change the side I start with, and then it works, easy peasy :)
Not forcing anyone else to use a 2032 it's just I find them easier to find in a multi-pack(generally 4) fresh name-brand batteries from a trusted B&M store for ~$6. The less common 2025 I can only find in a 2 pack as as mentioned before they are ~50% less capacity for more money :idea:
 
Is it reasonable to assume that any fob battery with sufficient power to operate the locking system from, say, 50 feet (15 metres) is good for use to drive the car? It is true to say that the 'face' voltage at the open terminals could be 3 volts and still collapse when loaded, but surely the load imposed by operating the locking system from such a distance would test the battery's reserve?
 
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