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Little Megger
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9 Posts
Discussion Starter · #1 ·
Hi,

I need some help because it seems that this problem is rare to happen, as I can't find almost no information on the subject.

I explain: I drive a Ford Mondeo Mk4 Titanium Station 2.0 TDCI, with almost 76.000 kms.

In the last few months (say in the last 4 months) I replaced my key fob battery for at least 5 or 6 times.

Immediately after changing the battery, all goes well, but a few days or a couple of weeks after an alert for low key battery comes out.

I tried using different brands of battery, but nothing seems to work.

Besides, the key working part (when activated for opening doors or start engine (with keyless system)) may the problem be on the receptor part of the system, that could be requesting too much times information from the key, an so draining the key battery (hope it's not a silly question)?

Thanks,

Luis
 

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1,383 Posts
Are you sure the message says "Key battery low" and not "Battery low"? The latter is the car battery itself.

Other than that, could it be picking up the spare key signal if parking up at your house or something similar?
 

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Little Megger
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9 Posts
Hi!
No, there is no doubt about the scenario.
I use the same Key for the last 6 years and I am changing its battery too often (almost once a month with brand new Duracell and other top brand batteries). As for the spare ke, iy is too far away from the car.
Tomorrow I'll try the spare key, that is my last "aceptable" solution at the moment.
Honestly, I believe help will still be needed here.
Many thanks
 

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Big Megger
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3,081 Posts
Thinking on the same lines as Mazo, you don't have your radio on with the engine off do you?

This causes the "low battery" light to come on.

I know you're saying "key battery" but confirming whether you're mistaken with it because it's easy to mistake the two.
 

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Big Megger
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3,130 Posts
It has been said (and I agree from experience) that Panasonic brand batteries give a better lifespan. I too have tried several brands but have come back to Panasonic. Testing the batteries that give a Low warning shows that the voltage drops away slowly under load, this means that the transmitted signal will be weaker (basic radio tech = low power signal means reduced range, result- warning message). Try it and see.
 

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Little Megger
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9 Posts
Discussion Starter · #6 ·
Hi again,
Thanks for the tips. I confirm that the warning is for key fob with low battery. Effectively it was so low that today I had to change it. Now I turned to the second (spare) key (which had its battery empty, since I never used it for as long as the car exists) and when changing the battery I notice that it was from Panasonic. For some time now I'll have this problem in stand-by but with the usual battery brand I think I'll confirm if it is from the bateries or not.
I will keep you updated.
Thank you all
 

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Be careful when inserting the battery. Grease from your fingers can cause a very poor contact with the battery holder. I'd clean the contacts with some contact cleaner, then only insert the battery holding the edge.

Varta batteries are the highest quality out there, but they're a bit pricey. We've done a lot of testing for products at work and they have significantly better characteristics than the competition.
 

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The same happened to me, its not the battery but the voltage in the key fob itself, that's what the dealer told me when the tested the voltage within the fob, i had replaced 4 batteries in as many months so they tested the fob then replaced it under warranty.

Kev
 

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I had the same problem. Batteries only lasted 2 or3 weeks until warning came up. I used many cheap ones and even Panasonic ones but still no joy. I then tried the Duracell dura lock battery and had no problems since then. I see that others have used Panasonic ones with success so I may have had a faulty one.
 
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