Key Fob battery

[Boz50]

Hi All
Bit of funny one for you! I decided to change the batteries in my key fobs mainly because I wasn't sure how old they were, and also because one was working intermittently.
Anyway I purchased two new Duracell CR2025 and swapped them over, only to find neither fob would work! So put the old batteries back in and lo and behold they both worked again.
I tested both the new batteries with a voltmeter and both show 3.35 volts but annoyingly they won't work in the fobs. Any ideas what's going on?
As always any advice gratefully received.
Many thanks in advance.
Tony

 

[Stanton]

This may sound silly, but let the fob "sit" for a bit (with the new battery in it)...and exercise all the buttons before giving up.
These things can take a lot of current, and sometimes you need to "pre-charge" the RF circuitry. I know, it sounds weird (and I'm an engineer).

 

[Boz50]

This may sound silly, but let the fob "sit" for a bit (with the new battery in it)...and exercise all the buttons before giving up.
These things can take a lot of current, and sometimes you need to "pre-charge" the RF circuitry. I know, it sounds weird (and I'm an engineer).

Hi Stanton
Thanks for the advice gave it another try as you suggested, let it rest exercised the buttons, lo and behold everything worked as it should.
All good now many thanks.
Tony.

 

[Boz50]

Hi Stanton
Thanks for the advice gave it another try as you suggested, let it rest exercised the buttons, lo and behold everything worked as it should.
All good now many thanks.
Tony.

 

[flydiver]

Fobs have harsh life. I find I usually have to clean the insides out. Then I put just a.....tiny.....amount of DeoxIT, D100L-CPK (Cell Phone Connector Cleaner) on the contacts. Great for cell phone charging ports after using micro swabs and contact cleaner to get the crap out.
Tiny bottle, but for these kind of applications it goes a really long way.
Good line of products.

FWIW, I was able to get 2032 in my 2 fobs (2014). I don't know if that works for all generations.

 

[Ancient1]

I switched from 2025's to 2032's in the 2 fobs for my 2019 SV+. Not a problem.

 

[Agkirk]

I switched from 2025's to 2032's in the 2 fobs for my 2019 SV+. Not a problem.

CR2032 here too in a 2015 Leaf

 

[lorenfb]

Hi All
Bit of funny one for you! I decided to change the batteries in my key fobs mainly because I wasn't sure how old they were, and also because one was working intermittently.
Anyway I purchased two new Duracell CR2025 and swapped them over, only to find neither fob would work! So put the old batteries back in and lo and behold they both worked again.
I tested both the new batteries with a voltmeter and both show 3.35 volts but annoyingly they won't work in the fobs. Any ideas what's going on?
As always any advice gratefully received.
Many thanks in advance.
Tony

The best way to test a "new" CR type battery is by doing a current test and not a simple voltage test which can be misleading.
Use a multimeter in a DC current mode, set to the highest scale. The reading in most cases should be greater than 200-300 ma.

 

[Boz50]

Thanks to all for the recent advice gratefully received.

 

[woeful]

The best way to test a "new" CR type battery is by doing a current test and not a simple voltage test which can be misleading.
Use a multimeter in a DC current mode, set to the highest scale. The reading in most cases should be greater than 200-300 ma.

Nissan's battery test is to check the CR2025's voltage with an approximately 300Ω (10 mA) load. If under 2.5 V, the battery is dead or faulty. That's a far gentler test than measuring the short-circuit current!

Old-stock coin cell batteries may well have lost some of their electrolyte and therefore have a good no-load voltage but a high internal resistance. Once I found that test I was able to put most of my card of 10 batteries in the recycling bag, and the key worked with one of the ones which passed.
(Nissan's diagram)
(I used two 150Ω resistors in series, since 300Ω is not a preferred value.)

 

[Nubo]

I switched from 2025's to 2032's in the 2 fobs for my 2019 SV+. Not a problem.

For some people this works fine; others have damaged their fobs this way. Adding the extra .7mm is really pushing the dimensions inside the fob. Actual production cells can deviate slightly from the specifications and these slight differences may mean the difference between success and failure. I understand 2025 may be harder to find but if they're available to you they're the better bet and give reasonably long service.

 

[lorenfb]

Nissan's battery test is to check the CR2025's voltage with an approximately 300Ω (10 mA) load. If under 2.5 V, the battery is dead or faulty. That's a far gentler test than measuring the short-circuit current!

Old-stock coin cell batteries may well have lost some of their electrolyte and therefore have a good no-load voltage but a high internal resistance. Once I found that test I was able to put most of my card of 10 batteries in the recycling bag, and the key worked with one of the ones which passed.
View attachment 5607(Nissan's diagram)
(I used two 150Ω resistors in series, since 300Ω is not a preferred value.)

Where is this provided? A 10ma load test is an inadequate test for a strong remote signal!

Datasheet:

 

[justin1990]

The variance in the 2025 battery thickness and the weakening of the spring seems to be enough that they get variable electrical contact. I tried a couple different 2025 batteries and none worked. The thicker 2032 battery fixed this problem for me and it also lasts longer. I wonder if there is more than one contractor for the fobs over the years.

 

[jjeff]

....I understand 2025 may be harder to find but if they're available to you they're the better bet and give reasonably long service.

It's not just that 2025 batteries are harder to find and cost the same if not more than the 2032 batteries but the 2032 batteries have almost double the capacity(mAh) so they will last longer. I also purchase the 2032 batteries in larger packs(3-10 pack) so I've always got fresh 2032 batteries laying around and not have to keep the oddball 2025 battery that I'd only use in a Leaf FOB. I guess if you don't regularly use or stock the 2032 batteries and don't mind spending more for less as far as capacity, then for all means use a 2025 as it is easier to close the FOB with a 2025.

 

[woeful]

Where is this provided? A 10ma load test is an inadequate test for a strong remote signal!

Try page DLK-107 of the LEAF service manual. Or page DLK-127 of the very similar e-NV200 service manual.

 

[lorenfb]

Try page DLK-107 of the LEAF service manual. Or page DLK-127 of the very similar e-NV200 service manual.

That test is basically the same inadequate test when load testing an automotive battery rated at 80 Ahrs at less than 8 amps.

 

[woeful]

That test is basically the same inadequate test when load testing an automotive battery rated at 80 Ahrs at less than 8 amps.

I disagree.

(a) The absolute maximum rated current for a CR2025 cell, as shown in the Duracell datasheet you helpfully posted, is 15 mA for 1 second, or 5 mA continuous. Testing the battery at 10 mA for a few seconds is realistic.

(b) If it's that bad, why is my key still working? Why does Nissan document this test for the keys of at least two vehicle models?

 

[lorenfb]

I disagree.

(a) The absolute maximum rated current for a CR2025 cell, as shown in the Duracell datasheet you helpfully posted, is 15 mA for 1 second, or 5 mA continuous. Testing the battery at 10 mA for a few seconds is realistic.

(b) If it's that bad, why is my key still working? Why does Nissan document this test for the keys of at least two vehicle models?

I never implied your battery was bad. My test is only momentariIy (<< 1 sec.), which I feel is a more effective test.

 

[ms60]

Hi All
Bit of funny one for you! I decided to change the batteries in my key fobs mainly because I wasn't sure how old they were, and also because one was working intermittently.
Anyway I purchased two new Duracell CR2025 and swapped them over, only to find neither fob would work! So put the old batteries back in and lo and behold they both worked again.
I tested both the new batteries with a voltmeter and both show 3.35 volts but annoyingly they won't work in the fobs. Any ideas what's going on?
As always any advice gratefully received.
Many thanks in advance.
Tony

As suggested by others let the new fob battery sit for a while, then try it. I put in a brand new one out of the package and it didn't work. Left it overnight. Worked in the morning

 

[rific]

This may sound silly, but let the fob "sit" for a bit (with the new battery in it)...and exercise all the buttons before giving up.
These things can take a lot of current, and sometimes you need to "pre-charge" the RF circuitry. I know, it sounds weird (and I'm an engineer).

Sorry but this is BS. It will work straight away or not at all. Something has to be wrong with battery swap.