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Keycard battery life - 24 hrs

Posted: Sun Jun 17, 2012 3:39 pm
by Glennst
Evening folks,

After 12 months of megane ownership I finally solved the misting windows / leakage problem..... but now the electrics are playing up.

It's a 2003 Megane 1.6 vvti Dynamique 3 door.

The battery in my Keycard stopped working, note it never actually said "replace keycard battery" on the dash, it just simply stopped opening and closing the doors one day. It did start the car fine when placed into the reader, but I've since learned that the keycard batteries are not required for the card reader to operate.

So I replaced the Keycard battery with a lithium cr2025, and hey presto it worked fine again. The doors locked / unlocked, and the card reader read the key from my pocket and all was well in the world.

The next morning nothing. Doors would not open and I had to enter the car manually via the emergency key, but once the card was inserted into the reader the car started fine. So I put this down to a dud replacement battery and bought a packet of four Duracell cr2025's.

Again I replaced the battery and again all was fine..... until the next morning. The same scenario occurred and I had to enter manually and once the Keycard was inserted into the reader the car started. I've been replaying this scenario for a month now, and I've spent about £25 on batteries.

I've checked all lights on the car for a possible car battery drain, and all are working fine. I've pulled out the reader, cleaned it, and it is working fine. I am now at a loss.

Why are my Keycard batteries only lasting 24 hours ?????

Anyone experienced this issue or have any advice ?

Thanks

Re: Keycard battery life - 24 hrs

Posted: Sun Jun 17, 2012 10:19 pm
by davelowe
Never heard of this issue, but I think you are looking in the wrong place.

The car's electrical systems are entirely separate from the key card. The starting system and immobiliser are passive - they require no electronics from car or card. Thus, the car runs normally.

My key card has the same cell as those you describe. So, I suspect that your problem is either the car is being locked/unlocked remotely by accident (it is kept too close to the car), or else something is shorting the cell. In the latter case, you might need to repair or replace it. Replacing it is expensive; and there is a guide on here detailing how to disassemble it and check for problems.

I believe the cell is a 3.3V unit. Personally, I would meter it periodically (ie every hour) during the day and see what its voltage reads. A rapid decline indicates either faulty cells (unlikely given the number you have got through), or else a short somewhere.

Let us know how you get on.

Re: Keycard battery life - 24 hrs

Posted: Mon Jun 18, 2012 1:31 pm
by Glennst
Dave,

Same thing again today. The keycard worked fine last night (opening and locking doors) yet this morning the keycard battery is completely dead (i just had it tested).

The key is kept well away from the car, anyway the car is parked in the same place for almost a year, and this problem has only arisen in recents months.

Following your advice am I right in saying that you believe the Keycard itself may be the issue, and is somehow shorting the battery each time ?

I have some notes on the delicate process of opening, inspecting, and repairing a keycard. I shall give this a go I think.

Re: Keycard battery life - 24 hrs

Posted: Mon Jun 18, 2012 1:42 pm
by AlexB
Don't fiddle with the card unless you have a spare one at hand!

If you don't have a spare card, they order it. Reliability of cards is limited by the human factor, which means that having a spare is a must!

Until the spare card arrives, save money on batteries by removing the battery when not in use or getting a rechargeable one.

Check if all buttons on the card work. I one of them does not work, it may be mechanically stuck-on, thus preventing the card from entering the sleep state...

Re: Keycard battery life - 24 hrs

Posted: Mon Sep 04, 2017 2:13 pm
by q292u
I wouldn't risk removing the battery for any length of time!
I'd be worried that it would lose some crucial (RenaultSpeak for "expensive") setting..

Re: Keycard battery life - 24 hrs

Posted: Tue Sep 05, 2017 12:15 pm
by q292u
BTW, what IS the correct battery type for the Megane 2 key card (standard one)?
The manual skirts around the issue, suggesting you buy a replacement from the dealer. Yeah. Right.

Re: Keycard battery life - 24 hrs

Posted: Thu Sep 07, 2017 1:34 pm
by snapdragon
CR2025 is correct.

Re: Keycard battery life - 24 hrs

Posted: Mon Sep 11, 2017 2:41 pm
by AlexB
It is safe to remove the battery from the card, no programming required after.

q292u wrote:I wouldn't risk removing the battery for any length of time!
I'd be worried that it would lose some crucial (RenaultSpeak for "expensive") setting..

Re: Keycard battery life - 24 hrs

Posted: Wed Oct 25, 2017 7:59 pm
by Muratak
I have the same problem

Any update on this

Thanks

Re: Keycard battery life - 24 hrs

Posted: Fri Oct 27, 2017 11:19 am
by NeilS
Glennst wrote:
The battery in my Keycard stopped working,

Why are my Keycard batteries only lasting 24 hours ?????


The card may have been dropped onto a hard surface - without your knowledge - and this could have caused some sort of short-circuit which has resulted in the battery charge level being dragged down. Is the card warm to the touch by any chance?

These cards are buggers to take apart, and just as bad to keep together after re-assembly. Sorry I can't offer something more constructive, but my advice would be to try to source the cheapest replacement you can.

Re: Keycard battery life - 24 hrs

Posted: Sun Nov 05, 2017 10:04 pm
by q292u
Just answering my own question.. the battery in my key card is a CR2025. I have just replaced mine after it locked me out in bandit country (east Cleveland).
I got in using the emergency key and started the car, drove it back to civilisation and bought a new battery from the only shop open on a Saturday night at 11pm - Tesco.. so I had to pay £5 for a twin pack of Duracell's. The good news is that the locking system is now working 100% for the first time in months. Can it really be this simple?