Good morning everyone,

 

So I have a weird issue with my key fob.  I am getting the "replace key fob battery" warning on the dash, so I had a new spare Duracell CR2025 battery still sealed in the packet.  I took it out and replaced the battery, but the fob would not work at all, no blink from the LED when I press a button on the fob.  So I took the new battery back out and put the old one (also a Duracell CR2025) back in, and the fob works fine again, still low battery warning though.  I measured the voltage with a multi-meter, and the old batteries voltage reads as 3.0 v. The new batteries voltage reads as 3.27v so it should work just fine, but every single time I put the new Duracell battery in, the fob stops working.  I have cleaned the new CR2025 with alcohol in case there was some sort of contamination causing a contact issue, but it still does not work.  Anybody got any ideas?

 

Thanks!!

Edited 23 June, 20205 yr by TheTokRa

It's a dud battery - try in the other keyfob. The contacts on the keyfob are bent, try straightening them. You inserted the battery upside down.

 

What happens if you install another battery? What about trying the battery from the spare key fob in your main keyfob?

 

How long ago did you buy that spare battery you had lying around?

2 minutes ago, Scot5 said:

It's a dud battery - try in the other keyfob. The contacts on the keyfob are bent, try straightening them. You inserted the battery upside down.

 

What happens if you install another battery? What about trying the battery from the spare key fob in your main keyfob?

 

How long ago did you buy that spare battery you had lying around?

Hi Scot5,  Thanks for your reply.  As I said, I have check the voltage of the cells, and the old battery is 3.0v the new one is 3.27v so it can't be a dud.  The batteries were probably bought at the same time (I think) and are from the same two pack blister pack.  The pack states that the cells should be good till 2026.   I have swapped the battery from new to old and back again about a dozen times now (making sure the battery is in the corect orientation) with the same result every time.  I'll dig out my spare keyfob and try the battery from that in it.  Just seems really odd, the battery contacts are fine, no issues there.

1 hour ago, TheTokRa said:

...so it can't be a dud.

 

Of course not 

 

It's the classic mistake we all make. Only eliminate it if it works in another device.

 

My neighbours Karcher pressure washer didn't work the other day. It worked 100% when plugged directly in to the socket, so it had to be the extention cable he was using, right?  That also worked 100% after testing it with my Karcher pressure washer so what was the problem?

 

 

 

 

 

I am having just the same issue so will watch with interest here.  As a precaution I am carrying a spare battery in my wallet (not leaving it in the car!!) and checked out the way to open the door manually, which is not obvious from the manual.  

   

I was gonna say there may be a sticker on the battery to remove, but as you've tested the battery already.................

I've got a Kessy key and the battery replacement info keeps flashing.

I know that changing a battery shouldn't be hard but I just wish the printed manual actually referred to my key in a more logical way as it doesn't make it straightforward and I don't want to risk breaking it!

1 hour ago, john999boy said:

I've got a Kessy key and the battery replacement info keeps flashing.

I know that changing a battery shouldn't be hard but I just wish the printed manual actually referred to my key in a more logical way as it doesn't make it straightforward and I don't want to risk breaking it!

Watch this video.  You can skip the first minute of the clip, it's just BS.

 

 

 

 

OK so this issue is really driving me nuts now.  Found the spare keyfob, took the battery out, it's also on it's way out at 3.01v so I put the new battery in that, and the LED blinks when I press a button.  Great I thought, but nope, althoughh the LED blinks when I press a button on the fob, the car does not resopnd to the button presses.  I put the old battery back in again, and keyfod works fine again.  repeated this process serveral time in a a row with the same results.  How can changing a the battery, that reads as being 3.27v AND makes the LED  blink when buttons are pressed, not open the freaking car doors?????

 

Apparently the fob only work if the battery is low!  WTF!!

1 hour ago, slast said:

I am having just the same issue so will watch with interest here.  As a precaution I am carrying a spare battery in my wallet (not leaving it in the car!!) and checked out the way to open the door manually, which is not obvious from the manual.  

   

Correct me if I'm wrong, but if the car was locked with the alarm set (by keyfob) then if you open the door with the key like in this video, won't you set off the alarm?  I'm sure I was another video to that affect a while back.

4 hours ago, Scot5 said:

 

Of course not 

 

It's the classic mistake we all make. Only eliminate it if it works in another device.

 

My neighbours Karcher pressure washer didn't work the other day. It worked 100% when plugged directly in to the socket, so it had to be the extention cable he was using, right?  That also worked 100% after testing it with my Karcher pressure washer so what was the problem?

Very odd!!  I'd still suspect a dodgy connection in the extension somewhere.  Loose wire at the plug, at the sockets end, or a damaged conductor inside the insulation. 

4 hours ago, Scot5 said:

 

 

 

 

 

 

1 hour ago, TheTokRa said:

Very odd!!  I'd still suspect a dodgy connection in the extension somewhere.  Loose wire at the plug, at the sockets end, or a damaged conductor inside the insulation. 

 

 

I suspect it's the same problem you're having. We test things, we find they work in one instance but not in the other.

 

You say the new battery is good yet when you placed it in the spare fob, it too didn't work. That suggests that whatever you say, your new battery is a bad 'un. I'm not saying it's go no charge, but I am saying that the + and - terminals may have an issue.

 

very easy to verify - If the spare keyfob was working ok with it's original battery, then what happens when you put that battery in to the keyfob you use daily?  I'll take a guess and say it works.

 

Regarding the pressure washer, that was a weird one. I then swapped extention cables and the neighbours power washer worked, so the problem was with his extention cable. But why? it worked with my pressure washer?  When we tested it, he had his washer on full power, my power washer was only turned up 3/4 power. When I put my washer on full, it didn't work. The washer must be drawing more current when on full which his extension cable wasn't capable of providing. So the only thing at fault was me, I hadn't conducted the test under like-4-like conditions. I suspect exactly the same may be true with you...  you believe the battery is working but is it working 100% as it should?

 

 

Edited 23 June, 20205 yr by Guest

@Scot5 Did your neighbours extension lead have a trip switch on it then???

2 hours ago, TheTokRa said:

Correct me if I'm wrong, but if the car was locked with the alarm set (by keyfob) then if you open the door with the key like in this video, won't you set off the alarm?  I'm sure I was another video to that affect a while back.

 

I think??? (but could be wrong) that if you then put the key in the ignition and turn it on, the alarm will go off, so long as the key has the immobiliser chip.

 

Guess it may differ on different cars also, maybe?

One thing that can go wrong with key fobs is if you touch the battery. you get grease from your fingers on the battery contacts, and there is not enough pressure from the contacts to puncture through the film of grease. If you use a multimeter, the low area of the contacts means they can puncture the grease film.

 

If this is problematic, clean well with alcohol and use gloves.

 

I don't know whether this is what is happening to you, but it is confusing.

 

 

1 hour ago, Tilt said:

 

I think??? (but could be wrong) that if you then put the key in the ignition and turn it on, the alarm will go off, so long as the key has the immobiliser chip.

 

Guess it may differ on different cars also, maybe?

Ah, right, so the alarm only goes off for a short period of time while you put the key in the ignition.  OK, well, at leas that gets you motoring again. Thanks!

42 minutes ago, Axle_of_weasels said:

One thing that can go wrong with key fobs is if you touch the battery. you get grease from your fingers on the battery contacts, and there is not enough pressure from the contacts to puncture through the film of grease. If you use a multimeter, the low area of the contacts means they can puncture the grease film.

 

If this is problematic, clean well with alcohol and use gloves.

 

I don't know whether this is what is happening to you, but it is confusing.

 

 

Yes, you are 100% correct, but as I mentioned in my first post, I did clean the battery with Alcohol in case of that very issue.

Edited 23 June, 20205 yr by TheTokRa

1 hour ago, Tilt said:

@Scot5 Did your neighbours extension lead have a trip switch on it then???

Was going to ask the same thing 👍

I will buy some more new CR2025 batteries next time at the shops,  See what happernsd with some other new batteries, but while not 100% accurate, multi-meters do not lie, if a battery consistently reads as 3.27v and the other battery that needs replaced reads as 3.0v that seems pretty accurate to me  I may have some CR2025's at work, but I'm not back in till Thursday.

5 hours ago, Tilt said:

@Scot5 Did your neighbours extension lead have a trip switch on it then???

 

Nope, just bog standard extention reel - must have been guage of cable in reel or perhaps a fault in the cable itself, but guessing washer drawing too high a current when on max.  Turn down power on washer and hey presto, it works.

 

Moral of story tho is if you're conducting test, then test it in like-4-like environment.  I have over 30 years of IT experience and I should have known better because things like that come up from time to time, you test everything and convince yourself there's no problem when in fact there is.

 

TheTokRa - did you try what I suggested above? What about the original battery that was in the spare key fob - was that working? What happened when you then put it in your main key fob?

Edited 24 June, 20205 yr by Guest

11 hours ago, TheTokRa said:

I will buy some more new CR2025 batteries next time at the shops,  See what happernsd with some other new batteries, but while not 100% accurate, multi-meters do not lie, if a battery consistently reads as 3.27v and the other battery that needs replaced reads as 3.0v that seems pretty accurate to me  I may have some CR2025's at work, but I'm not back in till Thursday.

 

Unless your multimeter has a dedicated battery test position that adds a resistor into the measuring circuit then you are not getting an accurate reading by just measuring the battery voltage on a normal volts dc range.

 

 

 

13 hours ago, TheTokRa said:

I will buy some more new CR2025 batteries next time at the shops,  See what happernsd with some other new batteries, but while not 100% accurate, multi-meters do not lie, if a battery consistently reads as 3.27v and the other battery that needs replaced reads as 3.0v that seems pretty accurate to me  I may have some CR2025's at work, but I'm not back in till Thursday.

But an open circuit voltage reading tells you nothing about the internal resistance of the battery, if that's high (due to aging maybe?) then as soon as the battery is on load (i.e. used in the key fob) the terminal voltage will drop.

That's a fair point guys, but surely the IR would need to be considerably higher on the new battery for the voltage to drop more on the new battery with an open voltage of 3.27v compared to the old battery with a open voltage of 3.0v?  As I said, I think these batteries were from the same twin blister pack, bought about a year ago I think, Does the IR in coin cells tend to increase if the cells are not used at all?  What value of resistive load would be comparable to the load of the fob?  I have some resistors laying around I could use to test.

9 hours ago, Scot5 said:

 

Nope, just bog standard extention reel - must have been guage of cable in reel or perhaps a fault in the cable itself, but guessing washer drawing too high a current when on max.  Turn down power on washer and hey presto, it works.

 

Moral of story tho is if you're conducting test, then test it in like-4-like environment.  I have over 30 years of IT experience and I should have known better because things like that come up from time to time, you test everything and convince yourself there's no problem when in fact there is.

 

TheTokRa - did you try what I suggested above? What about the original battery that was in the spare key fob - was that working? What happened when you then put it in your main key fob?

The spare keyfob battery is also around 3.0v and showing as needing replaced.  I'm sure it would work in the fob I use every day, but it would not resolve the issue.

Asda sell the battery's required