Key fob only works with old battery

[Simon_GH]

I changed the battery in one of my Ford keyless fobs with no problems.

The low battery warning appeared on the second fob. Battery duly changed to a new 2028 expiry Duracell. Key fob totally dead.

Replaced brand new Duracell with another brand new Duracell and fob still dead.

New Duracells work in another appliance and show 3v on a multimeter.

Just to rule out other causes, I put the original Panasonic battery back and the key fob worked again.

What’s going on?!

Thank you in advance

[E-bmw]

Have you checked to see if they have a "sticker" on one side to prevent shorting out while handling?

[take-good-care-of-the-forest-dewey]

Did exactly this a few weeks ago.

[Sheepshanks]

What size battery is it? VAG keyless fobs use CR2025 - you can get a pack of two Duracell's and one won't work, put the other in and it's fine.

The batteries test OK, although they really need a load on them to test properly.

[trevalvole]

What make of battery did you use in the first fob?

I ask because sometimes electronics can be sensitive to the type of battery used - I've had smoke alarms that recommend and only work with basic batteries, rather than super long-life ones.

[Simon_GH]

E-bmw said:

Have you checked to see if they have a "sticker" on one side to prevent shorting out while handling?

I appreciate the fast reply. I have removed a sticker from one side and the battery did work in my tire pressure gauge.

[Simon_GH]

Sheepshanks said:

What size battery is it? VAG keyless fobs use CR2025 - you can get a pack of two Duracell's and one won't work, put the other in and it's fine.

The batteries test OK, although they really need a load on them to test properly.

2032 - I’ve tried two new batteries but maybe it’s third time lucky! I know what you mean about a weak connection and/or weak battery will only fail when loaded.

[Simon_GH]

trevalvole said:

What make of battery did you use in the first fob?

I ask because sometimes electronics can be sensitive to the type of battery used - I've had smoke alarms that recommend and only work with basic batteries, rather than super long-life ones.

Thank you - I’ll check.

[Simon_GH]

Just to wrap up the thread - battery number 3 from same brand and purchase batch worked perfectly. Thanks for the help.